Error 500 using EntityManager in PostRequest - java

FINAL EDIT: Sorry I'm sure this post is very hard to follow, I'm updating it for future posterity. I never figured out what is the issue with my #PersistenceContext annotation, I ended up giving up and just moved on to using a CrudRepository instead.
our repository interface that implements from CrudRepository:
public interface RepositoryCar extends CrudRepository<Car, Long> {
}
Make a service Interface (not necessary but it's better practice):
public interface ServiceInterface {
Car addCar(Car car);
Car findCar(long carId);
}
make the implementing subclass #Service:
#Service
#Transactional
public class ServiceCar implements ServiceInterface{
//autowire this so it can instantiate your CrudRepository class.
#Autowired
RepositoryCar repositoryCar;
public Car addCar(Car car) {
return repositoryCar.save(car);
}
public Car findCar(long carId) {
Optional<Car> present=repositoryCar.findById(carId);
if(present.isPresent())
{
return present.get();
}
else
return null;
}
}
So that's my cluster of a post, I'm still curious as to why my #PersistenceContext wasn't picked up on somehow, but all my endpoints were setup correctly, I would still love to hear an explanation. I just moved on and used a CrudRepository though, there are multiple ways to do this.
Original post below:
I am trying to make a PostRequest and store information about my Car object using Spring Boot. I was following a guide where I have done this previously and it worked, so I'm trying to refollow that guide and my prior example, but I seem to be missing something. I get a generic error 500, and I'm not sure where to go from here.
my Car class:
#Entity
#Table(name = "cars")
public class Car {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
private String make;
private String model;
private String color;
private int year;
public Car(String make, String model, String color, int year) {
this.make = make;
this.model = model;
this.color = color;
this.year = year;
}
//getters and setters
My CarController class:
#RestController
#RequestMapping("/cars")
public class CarsController {
CarsRepository repository;
public CarsController(CarsRepository repository) {
this.repository = repository;
}
#PostMapping
public Car addCar(#RequestBody Car car) {
repository.addCar(car);
return car;
}
#GetMapping
public CarsRepository getCars() {
return repository;
}
}
My Car Repository:
#Repository
public class CarsRepository {
#PersistenceContext
EntityManager entityManager;
#Transactional
public void addCar(Car car) {
entityManager.persist(car);
}
public Car find(Long id) {
return entityManager.find(Car.class, id);
}
}
My Application.yml:
spring:
jpa:
generate-ddl: true
properties.hibernate.dialect: org.hibernate.dialect.MySQL5InnoDBDialect
datasource:
url: jdbc:mysql://localhost:3306/cars?useSSL=false
username: root
In my prior examples that work, I have used this same application.yml, and I double checked that I do not have a password set, so I have omitted that field.
I made a database and table. The following SQL code makes the table. Making the table in unnecessary as the table is automatically generated, I dropped the table and just had the database exist at the end of all this:
CREATE TABLE car (
id BIGINT(20) NOT NULL AUTO_INCREMENT,
make VARCHAR(20),
model VARCHAR(20),
color VARCHAR(20),
year INT,
PRIMARY KEY (id)
)
ENGINE = innodb
DEFAULT CHARSET = utf8;
My main SpringBootApplication class is very straightforward:
package study.example;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
I was wondering if my table was set up incorrectly somehow, so I copy pasted my prior working example and it too gave me an error 500, so I do not think my table is incorrect because I'm certain my prior table for a different Application works.
When I do my post request in PostMan, I always get back an error 500, so I changed it from EntityManger to just an in memory HashMap, and it works fine, so I'm certain it's the EntityManager that is the problem.
Is there some component that I'm missing here, or is something I've done wrong? I have spent far too much time on this, but it looks like I'm following my past example identically, but obviously not.
My post request:
{
"make" : "make",
"model" : "model",
"color" : "blue",
"year" : 2000
}
and the response is pretty useless, it just says
{
"timestamp": "2019-06-29T03:29:06.110+0000",
"status": 500,
"error": "Internal Server Error",
"message": "No message available",
"path": "/cars/"
}
Thank you for any help, it's greatly appreciated.
EDIT: I now realize I am actually getting some useful error message in the logs, as Dmitriy pointed out. I am getting a NullPointer Exception. Here is the entire stacktrace:
Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException: null
at study.example.CarsRepository.addCar(CarsRepository.java:19) ~[main/:na]
at study.example.CarsController.addCar(CarsController.java:23) ~[main/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_211]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_211]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_211]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_211]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209) ~[spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:891) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:877) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:661) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109) ~[spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.valves.RemoteIpValve.invoke(RemoteIpValve.java:685) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.34.jar:8.5.34]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_211]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_211]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.34.jar:8.5.34]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_211]
EDIT: I'm pretty sure it's my build.gradle that is the problem, because I don't see what else it could be. I'm surprised that it even compiles if that's the problem to be honest, but here it is anyways:
buildscript {
ext {
springBootVersion = "2.0.6.RELEASE"
springVersion = "5.0.10.RELEASE"
hibernateVersion = "5.2.17.Final"
slf4jVersion = "1.7.25"
junitVersion = "4.12"
mysqlVersion = "5.1.40"
}
repositories {
mavenCentral()
}
dependencies {
classpath "org.springframework.boot:spring-boot-gradle-plugin:$springBootVersion"
}
}
apply plugin: 'java'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'
repositories {
mavenCentral()
}
dependencies {
compile("org.springframework.boot:spring-boot-starter-web:$springBootVersion")
compile "com.fasterxml.jackson.dataformat:jackson-dataformat-csv:2.7.0"
compile("mysql:mysql-connector-java:6.0.6")
compile "org.springframework.boot:spring-boot-starter-tomcat"
compile "org.hibernate:hibernate-core:$hibernateVersion"
compile "org.slf4j:slf4j-api:$slf4jVersion"
testCompile("org.springframework.boot:spring-boot-starter-test:$springBootVersion")
}
springBoot {
buildInfo()
}
bootRun.environment([
"WELCOME_MESSAGE": "hello"
])


In your code for the class CarsRepository.java , you have provided the annotation #Transactional on the method .Try using it like below :
#Repository
#Transactional
public class CarsRepository {
#PersistenceContext
EntityManager entityManager;
public void addCar(Car car) {
entityManager.persist(car);
}
public Car find(Long id) {
return entityManager.find(Car.class, id);
}
}
#PersistenceContext: A persistence context handles a set of entities
which hold data to be persisted in some persistence store (e.g. a
database). In particular, the context is aware of the different states
an entity can have (e.g. managed, detached) in relation to both the
context and the underlying persistence store.

Related

[Java| SpringBoot]The Repository is not getting injected

I've been getting into Java again after some years only dealing with javascript and typescript, and I'm trying to get into Spring Boot.
It sounds really fun and convenient, but I'm trying to do something simple and for some reason I can't get my repository to get injected into my service. It sounds something really simple, but I've been digging for hours and can't get it to work.I'm wondering if some of you can help me to understand what I'm doing wrong ,please.
Thanks in advance
Projects (Entity)
package com.example.demo.modules.projects.entities;
import javax.persistence.*;
#Entity
#Table
public class Projects {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
#Column
private String project_name;
#Column
private String description;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getProject_name() {
return project_name;
}
public void setProject_name(String project_name) {
this.project_name = project_name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
The Repository
package com.example.demo.modules.projects.repositories;
import com.example.demo.modules.projects.entities.Projects;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
#Repository
public interface IProjectRepository extends JpaRepository<Projects, Long> {
}
CreateProjectsService
package com.example.demo.modules.projects.services;
import com.example.demo.modules.projects.entities.Projects;
import com.example.demo.modules.projects.repositories.IProjectRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
#Service
public class CreateProjectService {
#Autowired
IProjectRepository iProjectRepository;
public Projects execute(Projects project){
System.out.println("Received " + project.toString());
Projects CreatedProject= this.iProjectRepository.save(project);
System.out.println("Created " + CreatedProject);
return CreatedProject;
}
}
The Error
It seems to not be injecting/instantiating correctly.
2020-10-09 00:56:08.774 ERROR 5856 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException: Cannot invoke "com.example.demo.modules.projects.repositories.IProjectRepository.save(Object)" because "this.iProjectRepository" is null] with root cause
java.lang.NullPointerException: Cannot invoke "com.example.demo.modules.projects.repositories.IProjectRepository.save(Object)" because "this.iProjectRepository" is null
at com.example.demo.modules.projects.services.CreateProjectService.execute(CreateProjectService.java:17) ~[classes/:na]
at com.example.demo.ServerApplication.newEmployee(ServerApplication.java:26) ~[classes/:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:652) ~[tomcat-embed-core-9.0.38.jar:4.0.FR]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) ~[tomcat-embed-core-9.0.38.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.38.jar:9.0.38]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) ~[na:na]
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) ~[na:na]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at java.base/java.lang.Thread.run(Thread.java:832) ~[na:na]

The issue is because you did not allow Spring to instantiate CreateProjectService and takes control of the bean, probably you instantiated the object with new CreateProjectService().
The recommended approach is to create an interface e.g. ICreateProjectService like below:
public interface ICreateProjectService {
Projects execute(Projects project);
}
And then implement ICreateProjectService in CreateProjectService like below:
#Service
public class CreateProjectService implements ICreateProjectService {
#Autowired
private IProjectRepository iProjectRepository;
#Override
public Projects execute(Projects project) {
System.out.println("Received " + project.toString());
Projects CreatedProject= this.iProjectRepository.save(project);
System.out.println("Created " + CreatedProject);
return CreatedProject;
}
}
Then in your Controller layer, as an example of the service usage, autowire your service by injecting the interface, like below:
#Restcontroller
#RequestMapping("/api/v1")
public class CreateProjectRest {
#Autowired
private ICreateProjectService iCreateProjectService;
#PostMapping
public Projects execute(Projects project) {
createProjectService.execute(project);
// your code here
}
}
Now Spring is able to recognize CreateProjectService as a concrete implementation, instantiates it as a Spring bean, keeps it in Spring container and make it available for Dependency Injection wherever injected.
Hope this helps out.
UPDATE:
It is more advisable to inject dependencies via constructor than field or setter method.
#Restcontroller
#RequestMapping("/api/v1")
public class CreateProjectRest {
private ICreateProjectService iCreateProjectService;
/* No needed to annotate #Autowired after Spring 4.3.*/
public CreateProjectRest(ICreateProjectService iCreateProjectService){
this.iCreateProjectService = iCreateProjectService;
}
#PostMapping
public Projects execute(Projects project) {
createProjectService.execute(project);
// your code here
}
}

Reproducing Spring Data Rest search controllers in Spring Boot 2.3

Until Spring Boot 2.0, I could reproduce the controllers generated for query methods exposed by a mongodb repository.
Here is a code sample:
Domain Entity
#Document(collection = "foos")
public class Foo {
#Id
private String id;
private String name;
// getters/setters omitted
}
Mongo repository
public interface FooRepository extends MongoRepository<Foo, String> {
public Page<Foo> findByName(#Param("name") String name, Pageable pageable);
}
Spring Boot automatically exposes the search method through /foos/search/findByName?name=... with a result similar to this:
{
"_embedded" : {
"foos" : [ {
"name" : "qc",
"_links" : {
"self" : {
"href" : "http://localhost:8080/foos/56a8a8d5daffd28c9c907974"
},
"foo" : {
"href" : "http://localhost:8080/foos/56a8a8d5daffd28c9c907974"
}
}
} ]
},
"_links" : {
"self" : {
"href" : "http://localhost:8080/foos/search/findByName?name=qc&page=0&size=20"
}
},
"page" : {
"size" : 20,
"totalElements" : 1,
"totalPages" : 1,
"number" : 0
}
}
I could reproduce it with the following custom controller and configuration
#RestController
#RequestMapping("foos")
#RequiredArgsConstructor // lombok
public class FooQueryController {
private final FooRepository repository;
private final PagedResourcesAssembler pagedResourcesAssembler;
#GetMapping(value = "search/query",
produces = MediaType.APPLICATION_JSON_UT8_VALUE)
public ResponseEntity custom(#RequestParam("name") String name,
Pageable pageable,
PersistentEntityResourceAssembler resourceAssembler) {
var page = repository.findByName(name, pageable);
var model = pagedResourcesAssembler.toResource(page, resourceAssembler);
return ResponseEntity.ok(model);
}
}
// Enables injecting a PersistentEntityResourceAssembler in a RestController
// see https://jira.spring.io/browse/DATAREST-657 for details
#Configuration
#Order(Ordered.HIGHEST_PRECEDENCE)
#RequiredArgsConstructor
public class MvcConfiguration implements WebMvcConfigurer {
// WARNING: do NOT change the name of this member - it is injected with the
// RequestMappingHandlerAdapter$repositoryExporterHandlerAdapter().
private final RequestMappingHandlerAdapter repositoryExporterHandlerAdapter;
#Override
public void addArgumentResolvers(
List<HandlerMethodArgumentResolver> argumentResolvers) {
List<HandlerMethodArgumentResolver> customArgumentResolvers =
repositoryExporterHandlerAdapter.getCustomArgumentResolvers();
argumentResolvers.addAll(customArgumentResolvers);
}
}
With this I can send a request to /foos/search/query?name=... and get the expected response:
{
"_embedded" : {
"foos" : [ {
"name" : "qc",
"_links" : {
"self" : {
"href" : "http://localhost:8080/foos/56a8a8d5daffd28c9c907974"
},
"foo" : {
"href" : "http://localhost:8080/foos/56a8a8d5daffd28c9c907974"
}
}
} ]
},
"_links" : {
"self" : {
"href" : "http://localhost:8080/foos/search/query?name=qc&page=0&size=20"
}
},
"page" : {
"size" : 20,
"totalElements" : 1,
"totalPages" : 1,
"number" : 0
}
}
Switching to Spring Boot 2.3, using the Spring HATEOAS 1.0 API in the controller
#RestController
#RequestMapping("foos")
#RequiredArgsConstructor
public class FooQueryController {
private final FooRepository repository;
private final PagedResourcesAssembler pagedResourcesAssembler;
#GetMapping(value = "search/query",
produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity custom(#RequestParam("name") String name,
Pageable pageable,
PersistentEntityResourceAssembler resourceAssembler) {
var page = repository.findByName(name, pageable);
var model = pagedResourcesAssembler.toModel(page, resourceAssembler);
return ResponseEntity.ok(model);
}
}
I now get the following result:
{"_embedded":{"foos":[{"id":"56a8a8d5daffd28c9c907974","name":"qc","embeddeds":{},"nested":false,"persistentEntity":{"idProperty":{"name":"id","rawType":"java.lang.String","association":false,"owner":{"idProperty":{"name":"id","rawType":"java.lang.String","association":false,"owner":{"idProperty":{"name":"id","rawType":"java.lang.String","association":false,"owner":{"idProperty":{"name":"id","rawType":"java.lang.String","association":false,"owner":{"idProperty":{"name":"id","rawType":"java.lang.String","association":false,"owner":{"idProperty":{"name":"id","rawType":"java.lang.String","association":false,"owner":{"idProperty":{"name":"id","rawType":"java.lang.String","association":false,"owner":{"idProperty":{"name":"id","rawType":"java.lang.String","association":false,"owner":{"idProperty":{"name":"id","rawType":"java.lang.String","association":false,"owner":{"idProperty":{"name":"id","rawType":"java.lang.String","association":false,"owner":{"idProperty":
With the following errors in Spring's log:
2020-08-06 18:11:20.968 WARN 9932 --- [nio-8080-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Failure while trying to resolve exception [org.springframework.http.converter.HttpMessageNotWritableException]
java.lang.IllegalStateException: Cannot call sendError() after the response has been committed
at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:472) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver.sendServerError(DefaultHandlerExceptionResolver.java:550) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver.handleHttpMessageNotWritable(DefaultHandlerExceptionResolver.java:440) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver.doResolveException(DefaultHandlerExceptionResolver.java:210) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver.resolveException(AbstractHandlerExceptionResolver.java:141) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.handler.HandlerExceptionResolverComposite.resolveException(HandlerExceptionResolverComposite.java:80) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.processHandlerException(DispatcherServlet.java:1300) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1111) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1057) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:626) ~[tomcat-embed-core-9.0.37.jar:4.0.FR]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) ~[tomcat-embed-core-9.0.37.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.37.jar:9.0.37]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1589) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na]
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]
2020-08-06 18:11:20.979 ERROR 9932 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: Infinite recursion (StackOverflowError); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Infinite recursion (StackOverflowError) (through reference chain: org.springframework.data.mongodb.core.mapping.CachingMongoPersistentProperty["owner"]->org.springframework.data.mongodb.core.mapping.BasicMongoPersistentEntity["idProperty"]->org.springframework.data.mongodb.core.mapping.CachingMongoPersistentProperty["owner"]->org.springframework.data.mongodb.core.mapping.BasicMongoPersistentEntity["idProperty"]->org.springframework.data.mongodb.core.mapping.CachingMongoPersistentProperty["owner"]->org.springframework.data.mongodb.core.mapping.BasicMongoPersistentEntity["idProperty"]->org.springframework.data.mongodb.core.mapping.CachingMongoPersistentProperty["owner"]->org.springframework.data.mongodb.core.mapping.BasicMongoPersistentEntity["idProperty"]->org.springframework.data.mongodb.core.mapping.CachingMongoPersistentProperty["owner"]->org.springframework.data.mongodb.core.mapping.BasicMongoPersistentEntity["idProperty"]-> ... IT GOES ON AND ON LIKE THIS ... ->org.springframework.data.mongodb.core.mapping.BasicMongoPersistentEntity["idProperty"])] with root cause
java.lang.StackOverflowError: null
at java.base/java.lang.ClassLoader.defineClass1(Native Method) ~[na:na]
at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016) ~[na:na]
at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174) ~[na:na]
at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:800) ~[na:na]
at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:698) ~[na:na]
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:621) ~[na:na]
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:579) ~[na:na]
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178) ~[na:na]
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521) ~[na:na]
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:773) ~[jackson-databind-2.11.1.jar:2.11.1]
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) ~[jackson-databind-2.11.1.jar:2.11.1]
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:728) ~[jackson-databind-2.11.1.jar:2.11.1]
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:755) ~[jackson-databind-2.11.1.jar:2.11.1]
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) ~[jackson-databind-2.11.1.jar:2.11.1]
... IT GOES ON LIKE THIS FOR DOZENS AND DOZENS OF LINE
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:728) ~[jackson-databind-2.11.1.jar:2.11.1]
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:755) ~[jackson-databind-2.11.1.jar:2.11.1]
2020-08-06 18:11:21.553 ERROR 9932 --- [nio-8080-exec-1] s.e.ErrorMvcAutoConfiguration$StaticView : Cannot render error page for request [/foos/search/query] and exception [] as the response has already been committed. As a result, the response may have the wrong status code.
If if return the contents of var page = repository.findByName(name, pageable); instead of var model = pagedResourcesAssembler.toModel(page, resourceAssembler);, I get the following result:
{"content":[{"id":"56a8a8d5daffd28c9c907974","name":"qc"}],"pageable":{"sort":{"sorted":false,"unsorted":true,"empty":true},"offset":0,"pageNumber":0,"pageSize":20,"paged":true,"unpaged":false},"last":true,"totalPages":1,"totalElements":1,"size":20,"number":0,"sort":{"sorted":false,"unsorted":true,"empty":true},"numberOfElements":1,"first":true,"empty":false}
So the circular mess comes from the serialization pagedResourcesAssembler.toModel(page, resourceAssembler) (and probably the WebMvcConfigurer override).

I had the same StackOverflowError: null when I call PersistentEntityResourceAssembler.toModel(Object). My code returns a single EntityModel instead of a PagedModel. My problem is solved by switching to PersistentEntityResourceAssembler.toFullResource(Object).
The toModel(Object) uses excerpt projection while toFullResource(Object) does not. I don't have time to dig into the code to check what produces an infinite loop to cause stack overflow.
Look at the source code of PagedResourcesAssembler, PagedResourcesAssembler.toModel(Page, RepresentationModelAssembler) calls RepresentationModelAssember.toModel(Object).
So workaround 1 is copying the source code of PagedResourcesAssembler.toModel(Page, RepresentationModelAssembler) and use RepresentationModelAssember.toFullResource(Object).
Workaround 2 is extending the PagedResourcesAssembler and overriding the createModel(...) method.
Before making the workaround, I have one question. Why do you pass a PersistentEntityResourceAssembler to PagedResourcesAssembler? My code uses PersistentEntityResourceAssembler to add HTTP headers ETag and Last-Modified when my custom controller returns a single resource. What good does it have to use PersistentEntityResourceAssembler to build the response of a collection resource (paged resource)?

Thanks to this thread on Spring JIRA, I was able to:
convert the controller MultiValueMap parameters to a Predicate
use a RepositoryRestController instead of a RestController, ie be able to inject a PersistentEntityResourceAssembler into the controller method.
Custom models and models assembler, as suggested in the accepted answer, are not necessary.
Configure a QuerydslPredicateBuilder bean:
#Configuration
#RequiredArgsConstructor
public class QueryDslConfiguration {
private final ConversionService mvcConversionService;
private final QuerydslBindingsFactory querydslBindingsFactory;
#Bean
public QuerydslPredicateBuilder querydslPredicateBuilder() {
return new QuerydslPredicateBuilder(mvcConversionService, querydslBindingsFactory.getEntityPathResolver());
}
}
A service to convert a MultiValueMap to a Predicate:
#Service
#RequiredArgsConstructor(onConstructor = #__(#Autowired))
public class PredicateService {
private final QuerydslPredicateBuilder querydslPredicateBuilder;
private final QuerydslBindingsFactory querydslBindingsFactory;
public <T> Predicate getPredicateFromParameters(final MultiValueMap<String, String> parameters, Class<T> tClass) {
TypeInformation<T> typeInformation = ClassTypeInformation.from(tClass);
return querydslPredicateBuilder.getPredicate(typeInformation,
parameters,
querydslBindingsFactory.createBindingsFor(typeInformation));
}
}
Use the converter in a controller:
#RepositoryRestController
#RequiredArgsConstructor
public class FooController {
private final FooRepository repository;
private final PredicateService predicateService;
#GetMapping("/foos/search/query")
public PagedModel<Foo> query(
#RequestParam MultiValueMap<String, String> parameters,
Pageable pageable,
PersistentEntityResourceAssembler resourceAssembler) {
Predicate predicate = predicateService.getPredicateFromParameters(parameters, Foo.class);
Page<Parameter> page = repository.findAll(predicate,
return pagedResourcesAssembler.toModel(page, resourceAssembler);
}
}

How to implement a REST service with Spring Boot

I want to build a simple microservice with "Spring Boot" with IntelliJ IDE.
One method of this microservice should to accept in input a List and a Double Value.
So I'm building this code:
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
#RestController
public class ECGController {
private double v1 = 0.01;
private double v2 = 0.01;
private int il = 0;
private static final double step = 0.0025;
#PostMapping("/clearF3A")
public List<Double> clearF3A(ArrayList<Integer> RRin, Double CR){
try{
}catch(Exception e){
}
}
In postman I'm try to execute this:
{
"RRin":[
834,
490,
878,
807,
517,
849,
816,
520,
632,
488,
701,
536,
675
],
"CR":2.0
}
but if I try to execute this request, I can display this message error:
java.lang.NullPointerException
at com.eresult.cleanECG.com.cleanECG.controller.ECGController.clearF3A(ECGController.java:36)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:108)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
java.lang.NullPointerException

Your request is bad.
Instead of providing ArrayList<Integer> RRin, Double CR to clearF3A function, you should have one object that represents whole post body (whole JSON document). That is the rule. In your case, your passed object should have two parameters, one is rrin array, and second one should be cr. Also, that parameter should be annotated with #RequestBody
Roughly, this is what you need to have:
#PostMapping("/clearF3A")
public List<Double> clearF3A(#RequestBody ClearF3ARequest){
...
}
class ClearF3ARequest {
private ArrayList<Integer> RRin;
private Double CR;
}
Hope this helps.

Create a new object to represent your JSON structure. For example:
public class EcgInput {
#JsonProperty("RRin")
private List<Integer> rrIn;
#JsonProperty("CR")
private Double cr;
//todo: add the getters and setters and methods like toString()
}
public class EcgOutput {
#JsonProperty("output")
private List<Double> output;
//todo: add the getters and setters and methods like toString()
}
Then in your controller change your method to something like:
#PostMapping("/clearF3A")
public ResponseEntity<EcgOutput> clearF3A(#RequestBody EcgInput ecgInput) {
//todo: your logic
EcgOutput output = new EcgOutput();
//todo: put your result inside it
return new ResponseEntity<>(output, HttpStatus.OK);
}
Jackson will translate JSON to those objects, and vice-versa for you.

HttpClientErrorException on restTemplate.getForObject

I'm trying to get the data from "https://swapi.co/api/people/?format=json" and put it into a POJO using the RestTemplate.getForObject() method. I followed the following tutorial for consuming a RESTful webservice and adapted this for my own project: https://spring.io/guides/gs/consuming-rest/.
Upon following the tutorial somehow I got the code to work.. once.. I copied the exact code from the tutorial and I changed the source URL and the object to fit the data into. But when I try to create my own maven project, include all the needed dependencies I get a 403 forbidden Exception.
My code:
#RestController
public class CharacterListController {
#RequestMapping("/")
public SWData swData() {
RestTemplate restTemplate = new RestTemplate();
SWData swData = restTemplate.getForObject("https://swapi.co/api/people/?format=json", SWData.class);
return swData;
}
#JsonIgnoreProperties(ignoreUnknown = true)
public class SWData {
String next;
String results;
public String getNext() {
return next;
}
public void setNext(String next) {
this.next = next;
}
public String getResults() {
return results;
}
public void setResults(String results) {
this.results = results;
}
#Override
public String toString() {
return "SWData{" +
"next='" + next + '\'' +
", results='" + results + '\'' +
'}';
}
}
Stacktrace:
2019-05-28 15:00:28.800 ERROR 3643 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.web.client.HttpClientErrorException$Forbidden: 403 Forbidden] with root cause
org.springframework.web.client.HttpClientErrorException$Forbidden: 403 Forbidden
at org.springframework.web.client.HttpClientErrorException.create(HttpClientErrorException.java:83) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:122) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:102) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.client.ResponseErrorHandler.handleError(ResponseErrorHandler.java:63) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:778) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:736) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:670) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:311) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at io.github.BasPeter.SWAPI.rest.CharacterListController.swData(CharacterListController.java:16) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_211]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_211]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_211]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_211]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:892) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:200) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.17.jar:9.0.17]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_211]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_211]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.17.jar:9.0.17]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_211]
The most frustrating part is that the code functioned at some point. It looked like it worked using the gradle stuff provided by the tutorial, but wont work when using my own maven pom.
Somehow my request is rejected by the server (?), but i don't know why. I think my code is practically the same as the code in the tutorial..
-BP

You have some extra work to do :)
1- Change your SWData class so that it will mach the JSON document you recieve when you type the targeted url on your browser. So your class should look like the following:
#JsonIgnoreProperties(ignoreUnknown = true)
public class People {
private long count;
private String next;
private String previous;
private Infos results[];
// Constructors, getters and setters
// Extra: You can add the Lombock project to automatically generates, constructors // getters and setters
}
And here is the Infos class:
public class Infos {
private String name;
private long height;
private long mass;
private String hair_color;
private String skin_color;
private String eye_color;
private String birth_year;
private String gender;
private String homeworld;
private String films[];
private String species[];
private String vehicles[];
private String starships[];
private String created;
private String edited;
private String url;
// Constructors, getters and setters
}
2- Now, if you didn't notice, you're trying to access to an https url. So You have first to configure your RestTemplate in order to use SSL certificate for request. To do that, you should first add the Apache HttpClient dependancy to your pom.xml. Use the latest version for example:
<!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient -->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.8</version>
</dependency>
3- Once you have Apache HttpClient libraries in you project, you can now configure your RestTemplate. Here is how you do that:
// Imports
#RestController
public class CharacterListController {
#RequestMapping("/")
public SWData swData() {
CloseableHttpClient httpClient = HttpClients.custom()
.setSSLHostnameVerifier(new NoopHostnameVerifier())
.build();
HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
requestFactory.setHttpClient(httpClient);
RestTemplate restTemplate = new RestTemplate(requestFactory);
SWData swData = restTemplate.getForObject("https://swapi.co/api/people/?format=json", SWData.class);
return swData;
}
}
4- That's all, you have only to run your Spring-Boot application now. Hope that will be helpful. Keep me updated with :)

Spring Boot - There was an unexpected error (type=Internal Server Error, status=500)

After surfing to localhost:8080 i start getting this error on the console with an internal error that goes like this on the webpage : 'There was an unexpected error (type=Internal Server Error, status=500).'
java.lang.NullPointerException: null
at com.test.Service.StudentService.getAllStudents(StudentService.java:15) ~[classes/:na]
at com.test.Controller.StudentController.getAllStudents(StudentController.java:22) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_191]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_191]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_191]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_191]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:891) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498) [tomcat-embed-core-8.5.34.jar:8.5.34]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.34.jar:8.5.34]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_191]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_191]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.34.jar:8.5.34]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_191]
Here is the service file :
package com.test.Service;
import com.test.Dao.StudentsDao;
import com.test.Entity.Student;
import org.springframework.stereotype.Service;
import java.util.Collection;
#Service
public class StudentService {
private StudentsDao studentDao;
public Collection<Student> getAllStudents()
{
return studentDao.getAllStudents();
}
}
The controller file :
package com.test.Controller;
import com.test.Entity.Student;
import com.test.Service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import java.util.Collection;
#RestController
#RequestMapping("/students")
public class StudentController {
#Autowired
private StudentService studentservice;
#RequestMapping(method = RequestMethod.GET)
public Collection<Student> getAllStudents()
{
return studentservice.getAllStudents();
}
}
And finally the DAO file :
package com.test.Dao;
import com.test.Entity.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
#Repository
public class StudentsDao {
#Autowired
public static Map<Integer, Student> students;
static{
students = new HashMap<Integer, Student>(){
{
put(1, new Student(1, "Chadi", "Informatique"));
}
};
}
public Collection<Student> getAllStudents()
{
return this.students.values();
}
}
What's causing this error . And how can i fix it ?

at com.test.Service.StudentService.getAllStudents(StudentService.java:15) ~[classes/:na] says it all. Check the line 15 from StudentService ... there you have a null :)
Your DAO is null .. you forgot the #Autowired on the dao field

You are using a class that is annotated with #repository in your service class. So the spring framework already knows that the DAO class is bean. But instead of using the bean, you’re defining an object of class without initializing the value for it. So, you will got a null pointer exception.

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