Modifying object for each web service call - java

In our web application we have a lot of REST services. Suddenly it found out that we need to modify one object inside of each request before we go on.
So let's say we have n different controllers with REST services. In each controller, before we call the service from next layer, we need to modify an object inside the request.
The question is how to achieve this without providing hundreds of changes inside the controllers... Is there any simple way to do this?
UPDATE:
#RestController
public class OrderController {
#Autowired
private OrderService orderService;
#RequestMapping(path = "/order", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
public OrderResponse getOrderData(#RequestHeader HttpHeaders httpHeaders,
#RequestBody OrderDataRequest orderDataRequest) {
// Use here interceptor to modify the object Details
// (inside OrderDataRequest) before below call:
OrderResponse resp = orderService.getOrderData(orderDataRequest);
return resp;
}
#RequestMapping(path = "/cancel/{orderId}", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE)
public boolean cancelOrder(#RequestHeader HttpHeaders httpHeaders,
#RequestBody Details details, #PathVariable Integer orderId) {
// Use here interceptor to modify object Details before below call:
return orderService.cancelOrder(details, orderId);
}
}
In each controller I need to modift the object Details, which as you can see could be inside another object like in the first example or exist alone like in the second option.

You can use Spring AOP to achieve this. Another option using traditional Filters.

You should consider writing an interceptor, that would allow you to do what you want .
You could also use AOP to do this.. though, I think it's quite over-complicated, especially when such a solution already exists through interceptors!
EDIT :
A few other links :
EDIT 2 :
Follow the "before advice" from mykong.com example, then go that way to edit your specific object according to its class (for exemple) :
package com.your.company;
import java.lang.reflect.Method;
import org.springframework.aop.MethodBeforeAdvice;
public class HijackBeforeMethod implements MethodBeforeAdvice
{
#Override
public void before(Method method, Object[] args, Object target)
throws Throwable {
for(Object arg : args) {
if(com.your.company.OrderDataRequest.class.isAssignableFrom(arg.getClass())) {
// update you object here
}
}
}
}
- Get response body
- Json To Java

Related

Spring Boot - Ambiguous Mapping

Pulling my hair out over this one, makes absolutely no sense
#RestController("/firmwareAShkcwdsdskl")
public class FirmwareController {
#PostMapping(produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<Result> createNewFirmwareVersion(DetailedFirmwareVersionRequest detailedFirmwareVersionRequest) {
// Code Block
}
}
#RestController("/jobs/firmwareUpgrade")
public class FirmwareUpgradeController {
#PostMapping(produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<Result> createNewJob(DetailedFirmwareUpgradeRequest detailedFirmwareUpgradeRequest) {
// Code Block
}
}
Attempting to start my Spring Boot application with these two controllers is throwing the following error
Caused by: java.lang.IllegalStateException: Ambiguous mapping. Cannot map '/jobs/firmwareUpgrade' method
eshepherd.admin.api.controller.FirmwareUpgradeController#createNewJob(DetailedFirmwareUpgradeRequest)
to {POST , produces [application/json]}: There is already '/firmwareAShkcwdsdskl' bean method
eshepherd.admin.api.controller.FirmwareController#createNewFirmwareVersion(DetailedFirmwareVersionRequest) mapped.
The class name, method name, request mapping and parameters are all unique, I just don't understand it.
As you can tell I've descended into pure frustration trying all kinds of string changes to just get it to work initially, but if anyone could help me identify the problem I'd be extremely grateful.
Edit: Using Spring-Boot 2.2.4
As you mentioned in your own answer: Yes, you misunderstood. This is an easy one to confuse.
#RestController's value is the component name, not the request mapping path. Take a look at the source for org.springframework.web.bind.annotation.RestController#value.
It is very similar to org.springframework.stereotype.Component#value and the others in org.springframework.stereotype (in spring-context). You have have the correct annotations now:
#RestController
#RequestMapping("/firmware")
public class FirmwareRestController {
// ...
}
Okay.. I managed to get it compiling.. I think I was misunderstanding how you can use the #RestController annotation
If you provide
#RestController
#RequestMapping("/firmware")
Instead of
#RestController("/firmware")
It will build. I guess I had assumed the default argument on the controller would be more useful, and looked to be working as I expected from the build messages.
Hope this helps someone!
The framework is complaining that there exists a post path / from the 2 controllers where the mapping is not specified for any one of them hence it cannot distinguish the exact path.
Can you please try the following code:
#RestController
#RequestMapping("/firmwareAShkcwdsdskl")
public class FirmwareController {
#PostMapping(produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<Result> createNewFirmwareVersion(DetailedFirmwareVersionRequest detailedFirmwareVersionRequest) {
// Code Block
}
}
#RestController
#RequestMapping("/jobs/firmwareUpgrade")
public class FirmwareUpgradeController {
#PostMapping(produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<Result> createNewJob(DetailedFirmwareUpgradeRequest detailedFirmwareUpgradeRequest) {
// Code Block
}
}
#RequestMapping at controller level should define the root path for all the APIs in that path say for example I have to create a controller related to feeds API I would do:
#RestController
#RequestMapping("/api/feeds")
class FeedsController {
//Constructor inject fields here
#Autowired
FeedsController() {
}
#GetMapping("/")
ResponseEntity<Map<String, String>> get() {
return ResponseEntity.ok(Collections.emptyMap());
}
#PostMapping("/")
ResponseEntity<Map<String, String>> post() {
return ResponseEntity.ok(Collections.emptyMap());
}
/**
* Standard way to implement delete is to soft delete
* #return
*/
#DeleteMapping("/")
ResponseEntity<Map<String, String>> delete() {
return ResponseEntity.ok(Collections.emptyMap());
}
}

Service injected into spring controller is not available in one of the functions

I am writing spring controller, which injects a bean.
The bean is added in config(we use java config for everything):
#Bean
public NotificationService notificationService() {
return new NotificationService();
}
The service itself has few injected dependencies and few functions:
public class NotificationService {
#Inject
NotificationRepository notificationRepository;
#Inject
ProjectRepository projectRepository;
#Inject
ModelMapper modelMapper;
public NotificationDto create(NotificationDto notificationDto) {
//convert to domain object, save, return dto with updated ID
return notificationDto;
}
public void markAsRead(Long id, String recipientNip) {
//find notification, update status
}
}
Model mapper has almost no configuration, is only set to strict. Meanwhile repositoriers are interfaces extending JpaRepository with no custom functions. They are found by #EnableJpaRepositories.
Finally I have controller that tries to use the code above:
#RestController
#RequestMapping("/notifications")
public class NotificationController extends ExceptionHandlerController {
#Autowired
private NotificationService notificationService;
#PreAuthorize("isFullyAuthenticated() and hasRole('create_notification')")
#RequestMapping(method = RequestMethod.POST, consumes = MediaTypeExtension.APPLICATION_JSON_UTF8_VALUE)
public ResponseEntity<?> createNotification(#Valid #RequestBody(required = true) final NotificationDto notification) {
this.notificationService.create(notification);
final HttpHeaders headers = new HttpHeaders();
return new ResponseEntity<>(headers, HttpStatus.CREATED);
}
#PreAuthorize("isFullyAuthenticated() and hasRole('update_notification')")
#RequestMapping(value = "/{id}/read", method = RequestMethod.PUT)
private ResponseEntity<?> markNotificationAsRead(#PathVariable("id") Long id, #AuthenticatedContractor ContractorDto contractor) {
this.notificationService.markAsRead(id, contractor.getNip());
final HttpHeaders headers = new HttpHeaders();
return new ResponseEntity<>(headers, HttpStatus.OK);
}
}
All controllers are added trough #ComponentScan, based on their package.
As you can see both functions use notificationService. When I send POST for create on /notifications the notificationService is properly injected. In the same controller, when I do PUT request on /{id}/read, the notificationService is null.
I think it has something to do with spring putting things into its container, and for some reason not being able to do it for that one function. I have few more functions in the controller and in all of them notificationService is properly injected. I don't see any real difference between createNotification and markNotificationAsRead functions and I couldn't find anything even remotely related on google/stack. In all cases the service wouldn't inject at all because of configuration mistake.
Edit
I have tried changing things around in the function until it has started working. My final code looks like this:
#PreAuthorize("isFullyAuthenticated() and hasRole('update_notification')")
#RequestMapping(value = "{id}/read", method = RequestMethod.PUT)
public ResponseEntity<?> read(#PathVariable("id") Long id, #AuthenticatedContractor ContractorDto contractor) {
this.notificationService.markAsRead(id, contractor.getNip());
final HttpHeaders headers = new HttpHeaders();
return new ResponseEntity<>(headers, HttpStatus.OK);
}
and it works. Honestly I can't see any difference from my original code, and I have been staring at it for last hour or so. The imports are the same too.
I have also noticed(on unworking code) that while all functions from the controller on debug stack were marked as
NotificationController.functionName(arguments) line: x
The non working function was:
NotificationController$$EnhancerBySpringCGLIB$$64d88bfe(NotificationController).‌​markNotificationAsRead(ContractorDto) line: 86
Why this single function was enhanced by spring CGLIB I have no idea. I have tried looking it up, but for now I came empty handed. Even though the code started to work I am leaving the question open in order to find the underlying cause.
Your method markNotificationAsRead is private and that probably causes the issue. I've just had same issue with final method - this message appeared in log:
2016-11-28 17:19:14.186 INFO 97079 --- [ main] o.s.aop.framework.CglibAopProxy : Unable to proxy method [public final java.util.Map com.package.controller.MyController.someMethod(javax.servlet.http.HttpServletResponse)] because it is final: All calls to this method via a proxy will NOT be routed to the target instance.
Looks like in one case we see a CGLib proxy, and in another - the actual class. Only one of those has all the fields injected, looks like the proxy has all fields nulls. But it doesn't matter - the point is your method should be public and not final in order to be proxied properly by #PreAuthorize methods.
I was also facing the same issue. It was all due to the private access modifier used and #PreAuthorize. Making the controller method private does not make an issue if you do not make it secure. But, to make secure, make it public.

How to manage REST API versioning with spring?

I've been searching how to manage a REST API versions using Spring 3.2.x, but I haven't find anything that is easy to maintain. I'll explain first the problem I have, and then a solution... but I do wonder if I'm re-inventing the wheel here.
I want to manage the version based on the Accept header, and for example if a request has the Accept header application/vnd.company.app-1.1+json, I want spring MVC to forward this to the method that handles this version. And since not all methods in an API change in the same release, I don't want to go to each of my controllers and change anything for a handler that hasn't changed between versions. I also don't want to have the logic to figure out which version to use in the controller themselves (using service locators) as Spring is already discovering which method to call.
So taken an API with versions 1.0, to 1.8 where a handler was introduced in version 1.0 and modified in v1.7, I would like handle this in the following way. Imagine that the code is inside a controller, and that there's some code that is able to extract the version from the header. (The following is invalid in Spring)
#RequestMapping(...)
#VersionRange(1.0,1.6)
#ResponseBody
public Object method1() {
// so something
return object;
}
#RequestMapping(...) //same Request mapping annotation
#VersionRange(1.7)
#ResponseBody
public Object method2() {
// so something
return object;
}
This is not possible in spring as the 2 methods have the same RequestMapping annotation and Spring fails to load. The idea is that the VersionRange annotation can define an open or closed version range. The first method is valid from versions 1.0 to 1.6, while the second for version 1.7 onwards (including the latest version 1.8). I know that this approach breaks if someone decides to pass version 99.99, but that's something I'm OK to live with.
Now, since the above is not possible without a serious rework of how spring works, I was thinking of tinkering with the way handlers matched to requests, in particular to write my own ProducesRequestCondition, and have the version range in there. For example
Code:
#RequestMapping(..., produces = "application/vnd.company.app-[1.0-1.6]+json)
#ResponseBody
public Object method1() {
// so something
return object;
}
#RequestMapping(..., produces = "application/vnd.company.app-[1.7-]+json)
#ResponseBody
public Object method2() {
// so something
return object;
}
In this way, I can have closed or open version ranges defined in the produces part of the annotation. I'm working on this solution now, with the problem that I still had to replace some core Spring MVC classes (RequestMappingInfoHandlerMapping, RequestMappingHandlerMapping and RequestMappingInfo), which I don't like, because it means extra work whenever I decide to upgrade to a newer version of spring.
I would appreciate any thoughts... and especially, any suggestion to do this in a simpler, easier to maintain way.
Edit
Adding a bounty. To get the bounty, please answer the question above without suggesting to have this logic in the controller themselves. Spring already has a lot of logic to select which controller method to call, and I want to piggyback on that.
Edit 2
I've shared the original POC (with some improvements) in github: https://github.com/augusto/restVersioning
Regardless whether versioning can be avoided by doing backwards compatible changes (which might not always possible when you are bound by some corporate guidelines or your API clients are implemented in a buggy way and would break even if they should not) the abstracted requirement is an interesting one:
How can I do a custom request mapping that does arbitrary evaluations of header values from the request without doing the evaluation in the method body?
As described in this SO answer you actually can have the same #RequestMapping and use a different annotation to differentiate during the actual routing that happens during runtime. To do so, you will have to:
Create a new annotation VersionRange.
Implement a RequestCondition<VersionRange>. Since you will have something like a best-match algorithm you will have to check whether methods annotated with other VersionRange values provide a better match for the current request.
Implement a VersionRangeRequestMappingHandlerMapping based on the annotation and request condition (as described in the post How to implement #RequestMapping custom properties
).
Configure spring to evaluate your VersionRangeRequestMappingHandlerMapping before using the default RequestMappingHandlerMapping (e.g. by setting its order to 0).
This wouldn't require any hacky replacements of Spring components but uses the Spring configuration and extension mechanisms so it should work even if you update your Spring version (as long as the new version supports these mechanisms).
I just created a custom solution. I'm using the #ApiVersion annotation in combination with #RequestMapping annotation inside #Controller classes.
Example:
#Controller
#RequestMapping("x")
#ApiVersion(1)
class MyController {
#RequestMapping("a")
void a() {} // maps to /v1/x/a
#RequestMapping("b")
#ApiVersion(2)
void b() {} // maps to /v2/x/b
#RequestMapping("c")
#ApiVersion({1,3})
void c() {} // maps to /v1/x/c
// and to /v3/x/c
}
Implementation:
ApiVersion.java annotation:
#Target({ElementType.METHOD, ElementType.TYPE})
#Retention(RetentionPolicy.RUNTIME)
public #interface ApiVersion {
int[] value();
}
ApiVersionRequestMappingHandlerMapping.java (this is mostly copy and paste from RequestMappingHandlerMapping):
public class ApiVersionRequestMappingHandlerMapping extends RequestMappingHandlerMapping {
private final String prefix;
public ApiVersionRequestMappingHandlerMapping(String prefix) {
this.prefix = prefix;
}
#Override
protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
RequestMappingInfo info = super.getMappingForMethod(method, handlerType);
if(info == null) return null;
ApiVersion methodAnnotation = AnnotationUtils.findAnnotation(method, ApiVersion.class);
if(methodAnnotation != null) {
RequestCondition<?> methodCondition = getCustomMethodCondition(method);
// Concatenate our ApiVersion with the usual request mapping
info = createApiVersionInfo(methodAnnotation, methodCondition).combine(info);
} else {
ApiVersion typeAnnotation = AnnotationUtils.findAnnotation(handlerType, ApiVersion.class);
if(typeAnnotation != null) {
RequestCondition<?> typeCondition = getCustomTypeCondition(handlerType);
// Concatenate our ApiVersion with the usual request mapping
info = createApiVersionInfo(typeAnnotation, typeCondition).combine(info);
}
}
return info;
}
private RequestMappingInfo createApiVersionInfo(ApiVersion annotation, RequestCondition<?> customCondition) {
int[] values = annotation.value();
String[] patterns = new String[values.length];
for(int i=0; i<values.length; i++) {
// Build the URL prefix
patterns[i] = prefix+values[i];
}
return new RequestMappingInfo(
new PatternsRequestCondition(patterns, getUrlPathHelper(), getPathMatcher(), useSuffixPatternMatch(), useTrailingSlashMatch(), getFileExtensions()),
new RequestMethodsRequestCondition(),
new ParamsRequestCondition(),
new HeadersRequestCondition(),
new ConsumesRequestCondition(),
new ProducesRequestCondition(),
customCondition);
}
}
Injection into WebMvcConfigurationSupport:
public class WebMvcConfig extends WebMvcConfigurationSupport {
#Override
public RequestMappingHandlerMapping requestMappingHandlerMapping() {
return new ApiVersionRequestMappingHandlerMapping("v");
}
}
I have implemented a solution which handles PERFECTLY the problem with rest versioning.
General Speaking there are 3 major approaches for rest versioning:
Path-based approch, in which the client defines the version in URL:
http://localhost:9001/api/v1/user
http://localhost:9001/api/v2/user
Content-Type header, in which the client defines the version in Accept header:
http://localhost:9001/api/v1/user with
Accept: application/vnd.app-1.0+json OR application/vnd.app-2.0+json
Custom Header, in which the client defines the version in a custom header.
The problem with the first approach is that if you change the version let's say from v1 -> v2, probably you need to copy-paste the v1 resources that haven't changed to v2 path
The problem with the second approach is that some tools like http://swagger.io/ cannot distinct between operations with same path but different Content-Type (check issue https://github.com/OAI/OpenAPI-Specification/issues/146)
The solution
Since i am working a lot with rest documentation tools, i prefer to use the first approach. My solution handles the problem with the first approach, so you don't need to copy-paste the endpoint to the new version.
Let's say we have v1 and v2 versions for the User controller:
package com.mspapant.example.restVersion.controller;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
/**
* The user controller.
*
* #author : Manos Papantonakos on 19/8/2016.
*/
#Controller
#Api(value = "user", description = "Operations about users")
public class UserController {
/**
* Return the user.
*
* #return the user
*/
#ResponseBody
#RequestMapping(method = RequestMethod.GET, value = "/api/v1/user")
#ApiOperation(value = "Returns user", notes = "Returns the user", tags = {"GET", "User"})
public String getUserV1() {
return "User V1";
}
/**
* Return the user.
*
* #return the user
*/
#ResponseBody
#RequestMapping(method = RequestMethod.GET, value = "/api/v2/user")
#ApiOperation(value = "Returns user", notes = "Returns the user", tags = {"GET", "User"})
public String getUserV2() {
return "User V2";
}
}
The requirement is if i request the v1 for the user resource i have to take the "User V1" repsonse, otherwise if i request the v2, v3 and so on i have to take the "User V2" response.
In order to implement this in spring, we need to override the default RequestMappingHandlerMapping behavior:
package com.mspapant.example.restVersion.conf.mapping;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
public class VersionRequestMappingHandlerMapping extends RequestMappingHandlerMapping {
#Value("${server.apiContext}")
private String apiContext;
#Value("${server.versionContext}")
private String versionContext;
#Override
protected HandlerMethod lookupHandlerMethod(String lookupPath, HttpServletRequest request) throws Exception {
HandlerMethod method = super.lookupHandlerMethod(lookupPath, request);
if (method == null && lookupPath.contains(getApiAndVersionContext())) {
String afterAPIURL = lookupPath.substring(lookupPath.indexOf(getApiAndVersionContext()) + getApiAndVersionContext().length());
String version = afterAPIURL.substring(0, afterAPIURL.indexOf("/"));
String path = afterAPIURL.substring(version.length() + 1);
int previousVersion = getPreviousVersion(version);
if (previousVersion != 0) {
lookupPath = getApiAndVersionContext() + previousVersion + "/" + path;
final String lookupFinal = lookupPath;
return lookupHandlerMethod(lookupPath, new HttpServletRequestWrapper(request) {
#Override
public String getRequestURI() {
return lookupFinal;
}
#Override
public String getServletPath() {
return lookupFinal;
}});
}
}
return method;
}
private String getApiAndVersionContext() {
return "/" + apiContext + "/" + versionContext;
}
private int getPreviousVersion(final String version) {
return new Integer(version) - 1 ;
}
}
The implementation reads the version in the URL and asks from spring to resolve the URL .In case this URL does not exists (for example the client requested v3) then we try with v2 and so one until we find the most recent version for the resource.
In order to see the benefits from this implementation, let's say we have two resources: User and Company:
http://localhost:9001/api/v{version}/user
http://localhost:9001/api/v{version}/company
Let's say we made a change in company "contract" that breaks the client. So we implement the http://localhost:9001/api/v2/company and we ask from client to change to v2 instead on v1.
So the new requests from client are:
http://localhost:9001/api/v2/user
http://localhost:9001/api/v2/company
instead of:
http://localhost:9001/api/v1/user
http://localhost:9001/api/v1/company
The best part here is that with this solution the client will get the user information from v1 and company information from v2 without the need to create a new (same) endpoint from user v2!
Rest Documentation
As i said before the reason i select the URL-based versioning approach is that some tools like swagger do not document differently the endpoints with the same URL but different content type. With this solution, both endpoints are displayed since have different URL:
GIT
Solution implementation at:
https://github.com/mspapant/restVersioningExample/
I would still recommend using URL's for versioning because in URLs #RequestMapping supports patterns and path parameters, which format could be specified with regexp.
And to handle client upgrades (which you mentioned in comment) you can use aliases like 'latest'. Or have unversioned version of api which uses latest version (yeah).
Also using path parameters you can implement any complex version handling logic, and if you already want to have ranges, you very well might want something more soon enough.
Here is a couple of examples:
#RequestMapping({
"/**/public_api/1.1/method",
"/**/public_api/1.2/method",
})
public void method1(){
}
#RequestMapping({
"/**/public_api/1.3/method"
"/**/public_api/latest/method"
"/**/public_api/method"
})
public void method2(){
}
#RequestMapping({
"/**/public_api/1.4/method"
"/**/public_api/beta/method"
})
public void method2(){
}
//handles all 1.* requests
#RequestMapping({
"/**/public_api/{version:1\\.\\d+}/method"
})
public void methodManual1(#PathVariable("version") String version){
}
//handles 1.0-1.6 range, but somewhat ugly
#RequestMapping({
"/**/public_api/{version:1\\.[0123456]?}/method"
})
public void methodManual1(#PathVariable("version") String version){
}
//fully manual version handling
#RequestMapping({
"/**/public_api/{version}/method"
})
public void methodManual2(#PathVariable("version") String version){
int[] versionParts = getVersionParts(version);
//manual handling of versions
}
public int[] getVersionParts(String version){
try{
String[] versionParts = version.split("\\.");
int[] result = new int[versionParts.length];
for(int i=0;i<versionParts.length;i++){
result[i] = Integer.parseInt(versionParts[i]);
}
return result;
}catch (Exception ex) {
return null;
}
}
Based on the last approach you can actually implement something like what you want.
For example you can have a controller that contains only method stabs with version handling.
In that handling you look (using reflection/AOP/code generation libraries) in some spring service/component or in the same class for method with the same name/signature and required #VersionRange and invoke it passing all parameters.
The #RequestMapping annotation supports a headers element that allows you to narrow the matching requests. In particular you can use the Accept header here.
#RequestMapping(headers = {
"Accept=application/vnd.company.app-1.0+json",
"Accept=application/vnd.company.app-1.1+json"
})
This isn't exactly what you're describing, since it doesn't directly handle ranges, but the element does support the * wildcard as well as !=. So at least you could get away with using a wildcard for cases where all versions support the endpoint in question, or even all minor versions of a given major version (e.g. 1.*).
I don't think I've actually used this element before (if I have I don't remember), so I'm just going off the documentation at
http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/bind/annotation/RequestMapping.html
I already tried to version my API using the URI Versioning, like:
/api/v1/orders
/api/v2/orders
But there are some challenges when trying to make this work: how organize your code with different versions? How manage two (or more) versions at the same time? What's the impact when removing some version?
The best alternative that I found was not version the entire API, but control the version on each endpoint. This pattern is called Versioning using Accept header or Versioning through content negotiation:
This approach allows us to version a single resource representation
instead of versioning the entire API which gives us a more granular
control over versioning. It also creates a smaller footprint in the
code base as we don’t have to fork the entire application when
creating a new version. Another advantage of this approach is that it
doesn’t require implementing URI routing rules introduced by
versioning through the URI path.
Implementation on Spring
First, you create a Controller with a produces attribute, that will applied by default on each endpoint inside the same class.
#RestController
#RequestMapping(value = "/api/orders/", produces = "application/vnd.company.etc.v1+json")
public class OrderController {
}
After that, we can imagine a possible scenario where you have two versions (v1 and v2) of an endpoint for "create an order":
#Deprecated
#PostMapping
public ResponseEntity<OrderResponse> createV1(
#RequestBody OrderRequest orderRequest) {
OrderResponse response = createOrderService.createOrder(orderRequest);
return new ResponseEntity<>(response, HttpStatus.CREATED);
}
#PostMapping(
produces = "application/vnd.company.etc.v2+json",
consumes = "application/vnd.company.etc.v2+json")
public ResponseEntity<OrderResponseV2> createV2(
#RequestBody OrderRequestV2 orderRequest) {
OrderResponse response = createOrderService.createOrder(orderRequest);
return new ResponseEntity<>(response, HttpStatus.CREATED);
}
Done! Just call each endpoint using the desired Http Header version:
Content-Type: application/vnd.company.etc.v1+json
Or, to call the v2:
Content-Type: application/vnd.company.etc.v2+json
About your worries:
And since not all methods in an API change in the same release, I
don't want to go to each of my controllers and change anything for a
handler that hasn't changed between versions
As explained, this strategy maintains each Controller and endpoint with his actual version. You only modify the endpoint that have modifications and needs a new version.
And the Swagger?
Setup the Swagger with different versions is also very easy using this strategy. See this answer to more details.
What about just using inheritance to model versioning? That is what I'm using in my project and it requires no special spring configuration and gets me exactly what I want.
#RestController
#RequestMapping(value = "/test/1")
#Deprecated
public class Test1 {
...Fields Getters Setters...
#RequestMapping(method = RequestMethod.GET)
#Deprecated
public Test getTest(Long id) {
return serviceClass.getTestById(id);
}
#RequestMapping(method = RequestMethod.PUT)
public Test getTest(Test test) {
return serviceClass.updateTest(test);
}
}
#RestController
#RequestMapping(value = "/test/2")
public class Test2 extends Test1 {
...Fields Getters Setters...
#Override
#RequestMapping(method = RequestMethod.GET)
public Test getTest(Long id) {
return serviceClass.getAUpdated(id);
}
#RequestMapping(method = RequestMethod.DELETE)
public Test deleteTest(Long id) {
return serviceClass.deleteTestById(id);
}
}
This set up allows for little duplication of code and the ability to overwrite methods into new versions of the api with little work. It also saves the need to complicate your source code with version switching logic. If you don't code an endpoint in a version it will grab the previous version by default.
Compared to what others are doing this seems way easier. Is there something I'm missing?
In produces you can have negation. So for method1 say produces="!...1.7" and in method2 have the positive.
The produces is also an array so you for method1 you can say produces={"...1.6","!...1.7","...1.8"} etc (accept all except 1.7)
Ofcourse not as ideal as ranges that you have in mind but I think easier to maintain than other custom stuff if this is something uncommon in your system. Good luck!
You can use AOP, around interception
Consider having a request mapping which receives all the /**/public_api/* and in this method do nothing;
#RequestMapping({
"/**/public_api/*"
})
public void method2(Model model){
}
After
#Override
public void around(Method method, Object[] args, Object target)
throws Throwable {
// look for the requested version from model parameter, call it desired range
// check the target object for #VersionRange annotation with reflection and acquire version ranges, call the function if it is in the desired range
}
The only constraint is that all has to be in the same controller.
For AOP configuration have a look at http://www.mkyong.com/spring/spring-aop-examples-advice/

How can I hook into Spring's #RequestBody argument resolving to resolve my own argument using the body of the request

In the process of developing our app, we found ourselves doing something like this in our controller:
#RequestMapping(value = "foo", method = RequestMethod.POST)
#ResponseBody
public SimpleMasterWidget doStuff(#RequestBody ClientData clientData, ServerData serverData) throws Exception
{
pushClientDataToServerData(clientData, serverData);
//stuff specific to this operation on the serverData
return whatever;
}
The pushClientDataToServerData(clientData, serverData); call gets duplicated in every POST request. Now, I understand that there really shouldn't be any need to push clientData to serverData, but there is legacy code that forces us to do this.
Currently we are implementing the HandlerMethodArgumentResolver interface to resolve the ServerData argument. To remove all the duplicated pushClientDataToServerData calls I want to be able to resolve the ServerData argument with the ClientData already pushed into it.
Now in the argument resolver, I have access to the NativeWebRequest so I could probably get the request body through there and deserialize it and all that. However, I don't want to have to reimplement what Spring is already doing with the #RequestBody annotation.
So my question boils down to this: Is there a way I can call into Spring's stuff in the argument resolver so that I can get the deserialized ClientData object and call pushClientDataToServerData right within the argument resolver? Then all the controller methods would just look like this:
#RequestMapping(value = "foo", method = RequestMethod.POST)
#ResponseBody
public SimpleMasterWidget doStuff(ServerData serverData) throws Exception
{
//stuff specific to this operation on the serverData
return whatever;
}
And the pushClientDataToServerData call would be in only one place.
Thanks in advance.
Looks like a good candidate for Spring AOP. Below is just an example of pointcut, you should improve it to catch all possible methods:
#Component
#Aspect
public class PushClientDataAspect {
#Before(value = "execution(* com.xyz.myapp.dao.*.*(..) && args(clientData, serverData) && #annotation(org.springframework.web.bind.annotation.ResponseBody))")
public void pushClientData(ClientData clientData, ServerData serverData) {
pushClientDataToServerData(clientData, serverData);
}
}

Implementing dynamic menu for Spring MVC/AOP application

I wish to implement dynamically changeable menu (updating whenever annotated method or controller added) for my Spring MVC application.
What i want is to introduce new annotation (#RequestMenuMapping) which will go to #Controller beans and their methods (just like #RequestMapping works).
Heres is what i want, User class, producing menu like
Users
Index | List | Signup | Login
with following code:
#Controller
#RequestMapping("user")
#RequestMenuMapping("Users")
public class User {
#RequestMapping("")
#RequestMenuMapping("Index")
public String index(/* no model here - just show almost static page (yet with JSP checks for authority)*/) {
return "user/index.tile";
}
#RequestMapping("list")
#RequestMenuMapping("List")
public String list(Model model) {
model.addAttribute("userList",/* get userlist from DAO/Service */);
return "user/list.tile";
}
#RequestMapping("signup")
#RequestMenuMapping("Signup")
public String signup(Model model) {
model.addAttribute("user",/* create new UserModel instance to be populated by user via html form */);
return "user/signup.tile";
}
#RequestMapping("login")
#RequestMenuMapping("Login")
public String login(Model model) {
model.addAttribute("userCreds",/* create new UserCreds instance to be populated via html form with login and pssword*/);
return "user/login.tile";
}
}
I think that Spring AOP may help me to pointcut methods with #RequestMenuMapping annotation and via #AfterReturning add something representing web-site menu to model.
But this raises two questions:
How do i get Model instance in #AfterReturning advice method in case it is missing in adviced method (as in .index())?
How do i get all methods (as in java reflection Method) and classes (as in java reflection Class) annotated with #RequestMenuMapping in order to build complete menu index?
I think a better soultion would be a bean post processor to scan all controller classes for the #RequestMenuMapping and a HandlerInterceptor to add the menu items to every model map.
InterceptorDemo:
#Aspect
#Component
public class InterceptorDemo {
#Pointcut("#annotation(org.springframework.web.bind.annotation.RequestMapping)")
public void requestMapping() {
}
#Pointcut("#annotation(you.package.RequestMenuMapping)")
public void requestMenuMapping() {
}
#AfterReturning("requestMapping() && equestMenuMapping()")
public void checkServer(JoinPoint joinPoint,Object returnObj) throws Throwable {
Object[] args = joinPoint.getArgs();
Model m = (Model)args[0];
// use joinPoint get class or methd...
}
}
If you want to intercept Contoller with you own, you can wirte another pointcut and ProceedingJoinPoint object can get what you want.
Q1:
ModelAndView object create at org.springframework.web.servlet.DispatcherServlet.doDispatch()
// Actually invoke the handler.
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
// Do we need view name translation?
if (mv != null && !mv.hasView()) {
mv.setViewName(getDefaultViewName(request));
}
So, you can intercept handle method after returing or override the method.
Q2:As far as i know, there are two ways getting annotation methods.
1.Use AOP:
You can declare a pointcut like this:
#Pointcut("#annotation(you.package.RequestMenuMapping)")
public void requestMenuMappingPountcut() {
}
2.Use reflection.
Class clazz = Class.forName(classStr);
Method[] methods = clazz.getDeclaredMethods();
for (Method method : methods) {
if (method.isAnnotationPresent(RequestMapping.class)
&& method.isAnnotationPresent(RequestMenuMapping.class)) {
// do something
}
}

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