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Generating POJOs using OpenAPI generator with Lombok Annotations

I am using OpenAPI generator maven plugin like one below for generating Java client code for models .
<plugin>
<groupId>org.openapitools</groupId>
<artifactId>openapi-generator-maven-plugin</artifactId>
<version>4.3.1</version>
<executions>
<execution>
<goals>
<goal>generate</goal>
</goals>
<configuration>
<inputSpec>${project.basedir}/src/main/resources/api.yaml</inputSpec>
<generatorName>java</generatorName>
<configOptions>
<sourceFolder>src/gen/java/main</sourceFolder>
</configOptions>
</configuration>
</execution>
</executions>
</plugin>
When , I generate the model classes, they get generated with usual POJO field declarations and getters and setters. But what I want to do is, instead of generating getters and setters, I want my classes to get automatically generated with Lombok annotations for Java pojos like #Getter, #Setter, #Data, etc. Is there a way to customize model generator to fit above use case requirement?
I tried to find out if there is a way. I found this discussion, where the very last comment talks about a PR, where the issue of generating models using Lombok annotations has been addressed. But I do not see any clear indication of usage or any documentation of this feature in the OpenAPI generator open source project that it has been implemented yet. So, is there any way of generating models with Lombok annotations instead of regular getters and setters today?

To complete this very old thread: Now it does support Lombok annotations.
Example taken from here
<configOptions>
<additionalModelTypeAnnotations>#lombok.Builder #lombok.NoArgsConstructor #lombok.AllArgsConstructor</additionalModelTypeAnnotations>
</configOptions>

EDIT: This answer is deprecated. See the post by #Laess3r. I'll leave this, since it is applicable for older versions of openapi generator.
openapi-generator does not yet support Lombok annotations. If you want to generate code with Lombok annotations, you need to create a custom template in mustache, as described in https://openapi-generator.tech/docs/templating/.
If you've never worked with mustache, be aware that it's somewhat hard to read, so try to keep the templates as simple as possible and make sure to add unit tests to validate the generated output. The template will look something like this:
/**
* {{#description}}{{description}}{{/description}}
*/
#Data
public class {{classname}} {{#parent}}extends {{{parent}}} {{/parent}} {
{{#vars}}
/**
* {{#description}}{{description}}{{/description}}
*/
#JsonProperty("{{#lambda.lowercase}}{{nameInSnakeCase}}{{/lambda.lowercase}}")
private {{{datatypeWithEnum}}} {{name}};
{{/vars}}

I've been able to get this working out-of-the-box using a space
separated list of annotations on models:
#lombok.experimental.SuperBuilder #lombok.external.Jacksonized
If models have readOnly set to "true" the Builder becomes the only way to make the object and #Jacksonized allows it to be serialized/deserialized. There are some limitations with inheritance (turning off requiring all required parameters in the configOptions).

How to generate Swagger codegen Java models as JPA Entities

I am using Swagger codegen to create Java models to be used in a Spring REST server, and would like to know how to get Swagger to declare each model as a JPA entity.
I generate the code with the swagger-codegen-maven-plugin as follows:
<plugin>
<groupId>io.swagger</groupId>
<artifactId>swagger-codegen-maven-plugin</artifactId>
<version>2.4.0</version>
<executions>
<execution>
<goals>
<goal>generate</goal>
</goals>
<configuration>
<inputSpec>${project.basedir}/src/main/openApi/Rack.json</inputSpec>
<language>spring</language>
<groupId>com.me</groupId>
<artifactId>rest-server</artifactId>
<apiPackage>com.me.rest.api</apiPackage>
<modelPackage>com.me.rest.model</modelPackage>
<invokerPackage>com.me.rest.invoker</invokerPackage>
<configOptions>
<sourceFolder>src/gen/java/main</sourceFolder>
<java8>true</java8>
<dateLibrary>java8</dateLibrary>
</configOptions>
</configuration>
</execution>
</executions>
</plugin>
As I have it now, this is the abbreviated java code that gets generated:
#Validated
#javax.annotation.Generated(value = "io.swagger.codegen.languages.SpringCodegen", date = "...")
public class Rack {
#JsonProperty("id")
private Long id = null;
#JsonProperty("name")
private String name = null;
...
}
How do I get Swagger to add the #Entity and #Id JPA annotations, as follows?
import javax.persistence.Entity;
import javax.persistence.Id;
#Entity
#Validated
#javax.annotation.Generated(value = "io.swagger.codegen.languages.SpringCodegen", date = "...")
public class Rack {
#Id
#JsonProperty("id")
private Long id = null;
#JsonProperty("name")
private String name = null;
...
}
This way, all I would have to do to get Spring to automatically expose these generated classes as REST APIs, would be to add the following to my pom.xml:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-rest</artifactId>
</dependency>
Then I could create the JPA repositories with Spring-Data, as follows:
public interface RackRepository extends CrudRepository<Rack, Long> {
}

A PR has recently been merged fixing your issue : https://github.com/OpenAPITools/openapi-generator/pull/11775
You need to upgrade your Maven plugin to use the latest version (currently unreleased, only snapshot is available)
<plugin>
<groupId>org.openapitools</groupId>
<artifactId>openapi-generator-maven-plugin</artifactId>
<version>6.0.0-SNAPSHOT</version>
...
</plugin>
The configuration might be slightly different.
Then you need to add x-class-extra-annotation and x-field-extra-annotation in your spec.
For instance for the Pet Clinic:
schemas:
Pet:
type: object
x-class-extra-annotation: "#javax.persistence.Entity"
required:
- id
- name
properties:
id:
type: integer
format: int64
x-field-extra-annotation: "#javax.persistence.Id"
name:
type: string
tag:
type: string

While the right way to solve this surely is an extension of swagger-codegen (probably with the introduction of some kind of include/exclude config), I got away with a fairly simply post-processing of the generated files.
In contrast to the OP I use Gradle instead of Maven and leveraged its extended filtering functionality. For Maven it is probably necessary to run a Groovy-script by way of the Groovy-Maven-Plugin, since Maven only supports placeholder substitution (as does Ant, so using the AntRun-Plugin would also not work).
I used a simple heuristic to only include entities with an id - the logic is as follows:
for all Java-files containing an ID-field
include import statement for javax.persistence.* after the package declaration
add the #Entity-annotation before the class definition
for the ID-field, add the annotations #Id and #GeneratedValue
(based on field names, other annotations - #OneToMany etc. - may be added as well)
Gradle-users may find the following task useful as a start:
task generateJpaAnnotations(type: Copy) {
from "${swaggerSources.<modelName>.code.outputDir}/src/main/java"
into "<output dir>
include '**/*.java'
eachFile {
if (it.file.text.contains("private Long id")) {
filter { line -> line.contains('package') ? "$line\nimport javax.persistence.*;" : line }
filter { line -> line.contains('public class') ? "#Entity\n$line" : line }
filter { line -> line.contains('private Long id') ? "#Id\n#GeneratedValue(strategy=GenerationType.AUTO)\n$line" : line } }
}
}

So I'm actually asking myself the same question.
I found an example but the guy is simply re-defining his POJOs and providing a way to adapt the generated ones to the handwritten ones. Tedious and not evolutive.
Globally this could be hard because I'm not sure there is a way in your swagger to decide which POJO will be JPA enabled and maybe you don't want them all in your DB (?) Also, how to you tag the id in swagger?
If you know of such a way, you can always modify the mustache (pojo.mustache I guess) to give you the annotations you're missing.

SQL strings added more than once for: tablename

I'm bootstrapping a database using hibernate-maven-plugin, using models that it scans in the maven module it's executed in.
Unfortunately, it stops when hibernate throws this:
org.hibernate.tool.schema.spi.SchemaManagementException: SQL strings added more than once for: reference_data_source.UK-UK_9ec6wdvyj3mjagiptcnrq2txv
at org.hibernate.tool.schema.internal.SchemaCreatorImpl.checkExportIdentifier(SchemaCreatorImpl.java:299)
at org.hibernate.tool.schema.internal.SchemaCreatorImpl.doCreation(SchemaCreatorImpl.java:255)
at org.hibernate.tool.schema.internal.SchemaCreatorImpl.doCreation(SchemaCreatorImpl.java:128)
at org.hibernate.tool.hbm2ddl.SchemaExport.<init>(SchemaExport.java:199)
So, I have two persistence units, and some tables exists in both. Hibernate seems to interpret this like the same table though, so when it tries to store the same index, but for another schema, it fails thinking it is a duplicate. Their code can be found here.
I'm not sure how to approach this, anyway to configure hibernate hbm2ddl to keep track of these different peristence units?
This is the configuration for the hibernate-maven-plugin:
<plugin>
<groupId>de.juplo</groupId>
<artifactId>hibernate-maven-plugin</artifactId>
<version>2.0.0</version>
<configuration>
<detail>true</detail>
<persistenceUnit>mainPersistenceUnit</persistenceUnit>
<driver>com.mysql.jdbc.Driver</driver>
<dialect>org.hibernate.dialect.MySQL5Dialect</dialect>
<force>true</force>
<url><![CDATA[jdbc:mysql://localhost/auto_bootstrap_schema]]></url>
<username>user</username>
<password>pass</password>
</configuration>
<executions>
<execution>
<goals>
<goal>create</goal>
</goals>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql-connector-java.version}</version>
</dependency>
</dependencies>
</plugin>

I had the same problem. The reason in my case was that I had three entities starting with same prefix name and a OneToMany relation to the each more specialized one:
Person
PersonCard
PersonCardLayout
Renaming my model to this solved my problem:
Person
Card
Layout
This seems to be a bug in Hibernate.

i have the same problem, looks like a bug in:
org.hibernate.mapping.UniqueKey#getExportIdentifier
#Override
public String getExportIdentifier() {
return StringHelper.qualify( getTable().getName(), "UK-" + getName() );
}
because the identifier was build only from table name but without schema/catalog of the table.
Therefore, if you have to entities with same table name but different schema and in these entities two properties with same name and "unique = true" you will drop into the bug.

Another solution to this is to make use of #Table.
For example:
#Table(name="PERSON")
This happened to me when I had two classes representing two entities (#Entity) as follows:
#Entity
public class User {...}
#Entity
public class UserRoles {...}
I fixed this error by specifying the table name as follows:
#Entity
#Table(name="USER")
public class User {...}
And:
#Table(name="USER_ROLES")
#Entity
public class UserRoles {...}

Not sure if this is the same as what I ran into, but I had the same error issue with base class marked with #Entity annotation: changing to #MappedSuperclass removed the error.
Good Luck,
Ray

Use Spring Data JPA, QueryDSL to update a bunch of records

I'm refactoring a code base to get rid of SQL statements and primitive access and modernize with Spring Data JPA (backed by hibernate). I do use QueryDSL in the project for other uses.
I have a scenario where the user can "mass update" a ton of records, and select some values that they want to update. In the old way, the code manually built the update statement with an IN statement for the where for the PK (which items to update), and also manually built the SET clauses (where the options in SET clauses can vary depending on what the user wants to update).
In looking at QueryDSL documentation, it shows that it supports what I want to do. http://www.querydsl.com/static/querydsl/4.1.2/reference/html_single/#d0e399
I tried looking for a way to do this with Spring Data JPA, and haven't had any luck. Is there a repostitory interface I'm missing, or another library that is required....or would I need to autowire a queryFactory into a custom repository implementation and very literally implement the code in the QueryDSL example?

You can either write a custom method or use #Query annotation.
For custom method;
public interface RecordRepository extends RecordRepositoryCustom,
CrudRepository<Record, Long>
{
}
public interface RecordRepositoryCustom {
// Custom method
void massUpdateRecords(long... ids);
}
public class RecordRepositoryImpl implements RecordRepositoryCustom {
#Override
public void massUpdateRecords(long... ids) {
//implement using em or querydsl
}
}
For #Query annotation;
public interface RecordRepository extends CrudRepository<Record, Long>
{
#Query("update records set someColumn=someValue where id in :ids")
void massUpdateRecords(#Param("ids") long... ids);
}
There is also #NamedQuery option if you want your model class to be reusable with custom methods;
#Entity
#NamedQuery(name = "Record.massUpdateRecords", query = "update records set someColumn=someValue where id in :ids")
#Table(name = "records")
public class Record {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
//rest of the entity...
}
public interface RecordRepository extends CrudRepository<Record, Long>
{
//this will use the namedquery
void massUpdateRecords(#Param("ids") long... ids);
}
Check repositories.custom-implementations, jpa.query-methods.at-query and jpa.query-methods.named-queries at spring data reference document for more info.

This question is quite interesting for me because I was solving this very problem in my current project with the same technology stack mentioned in your question. Particularly we were interested in the second part of your question:
where the options in SET clauses can vary depending on what the user
wants to update
I do understand this is the answer you probably do not want to get but we did not find anything out there :( Spring data is quite cumbersome for update operations especially when it comes to their flexibility.
After I saw your question I tried to look up something new for spring and QueryDSL integration (you know, maybe something was released during past months) but nothing was released.
The only thing that brought me quite close is .flush in entity manager meaning you could follow the following scenario:
Get ids of entities you want to update
Retrieve all entities by these ids (first actual query to db)
Modify them in any way you want
Call entityManager.flush resulting N separate updates to database.
This approach results N+1 actual queries to database where N = number of ids needed to be updated. Moreover you are moving the data back and forth which is actually not good too.
I would advise to
autowire a queryFactory into a custom repository
implementation
Also, have a look into spring data and querydsl example. However you will find only lookup examples.
Hope my pessimistic answer helps :)

Mapping JSON object to Hibernate entity

I'm going to start a project of a REST application managed with Spring and with Hibernate for my model.
I know that Spring allows you to get Java object from the HTTP Request (with #Consumes(JSON) annotation). Is there any conflict if this Java object is also a Hibernate entities? And is nested object working (like #ManyToOne relation)?

Maven dependency
The first thing you need to do is to set up the following Hibernate Types Maven dependency in your project pom.xml configuration file:
<dependency>
<groupId>com.vladmihalcea</groupId>
<artifactId>hibernate-types-52</artifactId>
<version>${hibernate-types.version}</version>
</dependency>
Domain model
Now, if you are using PostgreSQL, you need to use the JsonType from Hibernate Types.
In order to use it in your entities, you will have to declare it on either class level or in a package-info.java package-level descriptor, like this:
#TypeDef(name = "json", typeClass = JsonType.class)
And, the entity mapping will look like this:
#Type(type = "json")
#Column(columnDefinition = "json")
private Location location;
If you're using Hibernate 5 or later, then the JSON type is registered automatically by the Postgre92Dialect.
Otherwise, you need to register it yourself:
public class PostgreSQLDialect extends PostgreSQL91Dialect {
public PostgreSQL92Dialect() {
super();
this.registerColumnType( Types.JAVA_OBJECT, "json" );
}
}
The JsonType works with Oracle, SQL Server, PostgreSQL, MySQL, and H2 as well. Check out the project page for more details about how you can map JSON column types on various relational database systems.

Yes, this wouldn't be a problem and is actually a fairly common practice.
In the recent years I have come to realize that sometimes, however, it is not a good idea to always build your views based on your domain directly. You can take a look at this post:
http://codebetter.com/jpboodhoo/2007/09/27/screen-bound-dto-s/
It is also known as "Presentation Model":
http://martinfowler.com/eaaDev/PresentationModel.html
The idea behind that is basically the following:
Imagine you have the domain entry User, who looks like that :
#Entity
#Data
public class User {
#Id private UUID userId;
private String username;
#OneToMany private List<Permission> permissions;
}
Let's now imagine you have a view where you wanna display that user's name, and you totally don't care about the permissions. If you use your approach of immediately returning the User to the view, Hibernate will make an additional join from the Permissions table because event though the permissions are lazily loaded by default, there is no easy way to signal to the jackson serializer or whatever you are using, that you don't care about them in this particular occasion, so jackson will try to unproxy them (if your transaction is still alive by the time your object is put for json serialization, otherwise you get a nasty exception). Yes, you can add a #JsonIgnore annotation on the permissions field, but then if you need it in some other view, you are screwed.
That a very basic example, but you should get the idea that sometimes your domain model can't be immediately used to be returned to the presentation layer, due to both code maintainability and performance issues.

We were using such approach to simplify design and get rid of many dtos (we were abusing them too much). Basically, it worked for us.
However, in our REST model we were trying to do not expose other relations for an object as you can always create another REST resources to access them.
So we just put #JsonIgnore annotations to relations mappings like #OneToMany or #ManyToOnemaking them transient.
Another problem I see that if you still like to return these relations you would have to use Join.FETCH strategy for them or move transaction management higher so that transaction still exists when a response is serialized to JSON (Open Session In View Pattern).
On my opinion these two solutions are not so good.

You can map the json request without using any library at REST web-services (Jersy)
this sample of code:
This hibernate entity called book:
#Entity
#Table(name = "book", schema = "cashcall")
public class Book implements java.io.Serializable {
private int id;
private Author author; // another hibernate entity
private String bookName;
//setters and getters
}
This web-services function
#POST
#Produces(MediaType.APPLICATION_JSON)
#Consumes(MediaType.APPLICATION_JSON)
public String addBook(Book book) {
String bookName=book.getName();
return bookName;
}
This is sample json request:
{
"bookName" : "Head First Java",
"author" : {
"id" : 1
}
}

Since you are just starting, perhaps you could use Spring Data REST?
This is the project: http://projects.spring.io/spring-data-rest/
And here are some simple examples:
https://github.com/spring-projects/spring-data-book/tree/master/rest
https://github.com/olivergierke/spring-restbucks
As you can see in the examples, there are no extra DTOs beyond the #Entity annotated POJOs.