How to use several date classes for code generation by openapi-generator-maven-plugin?

Question

I am using openapi-generator-maven-plugin with next config:

<plugin>
            <groupId>org.openapitools</groupId>
            <artifactId>openapi-generator-maven-plugin</artifactId>
            <version>6.0.1</version>
            <executions>
                <execution>
                    <id>spring-code-generation</id>
                    <goals>
                        <goal>generate</goal>
                    </goals>
                    <configuration>
                        <typeMappings>
                            <typeMapping>OffsetDateTime=ZonedDateTime</typeMapping>
                        </typeMappings>
                        <importMappings>
                            <importMapping>java.time.OffsetDateTime=java.time.ZonedDateTime</importMapping>
                        </importMappings>
                        <inputSpec>
                            ${project.basedir}/openapi.yml
                        </inputSpec>
                        <generatorName>spring</generatorName>
                        <apiPackage>api-swagger.api</apiPackage>
                        <modelPackage>api-swagger.model</modelPackage>
                        <supportingFilesToGenerate>
                            ApiUtil.java
                        </supportingFilesToGenerate>
                        <configOptions>
                            <sourceFolder>src/main/java/</sourceFolder>
                            <delegatePattern>true</delegatePattern>
                            <interfaceOnly>true</interfaceOnly>
                            <library>spring-boot</library>
                        </configOptions>
                    </configuration>
                </execution>
            </executions>
        </plugin>

I need to have ability to use several datetime java classes for my models - some needs to be ZonedDateTime, some other LocalDateTime and another needs to be Date class.

Something like this:

 SomeDto:
  required:
    - dateTime
  type: object
  properties:
    dateTime:
      type: string
      format: ZonedDateTime

 SomeOtherDto:
  required:
    - dateTime
  type: object
  properties:
    dateTime:
      type: string
      format: LocalDateTime

Can I have such a logic by using openapi-generator-maven-plugin ?

Answer 1

Yes, you are so close. Try this:

<typeMappings>
    <typeMapping>OffsetDateTime=OffsetDateTime</typeMapping>
    <typeMapping>ZonedDateTime=ZonedDateTime</typeMapping>
    <typeMapping>LocalDateTime=LocalDateTime</typeMapping>
</typeMappings>
<importMappings>
    <importMapping>OffsetDateTime=java.time.OffsetDateTime</importMapping>
    <importMapping>ZonedDateTime=java.time.ZonedDateTime</importMapping>
    <importMapping>LocalDateTime=java.time.LocalDateTime</importMapping>
</importMappings>

What this is doing is telling the generator that any type of OffsetDateTime is equal to the class OffsetDateTime. Then, it tells the generator that any time the class OffsetDateTime is used, the import for that class is java.time.OffsetDateTime.

So, you can also have custom type mappings that will still use the java class. You don't have to name them after the class name. For example, the following will still work:

<typeMappings>
    <typeMapping>offset=OffsetDateTime</typeMapping>
    <typeMapping>zoned=ZonedDateTime</typeMapping>
    <typeMapping>local=LocalDateTime</typeMapping>
</typeMappings>
<importMappings>
    <importMapping>OffsetDateTime=java.time.OffsetDateTime</importMapping>
    <importMapping>ZonedDateTime=java.time.ZonedDateTime</importMapping>
    <importMapping>LocalDateTime=java.time.LocalDateTime</importMapping>
</importMappings>

when used with this schema:

    SomeDto:
      required:
        - dateTime
      type: object
      properties:
        dateTime:
          type: string
          format: zoned
    SomeOtherDto:
      required:
        - dateTime
      type: object
      properties:
        dateTime:
          type: string
          format: local
    EvenAnotherDto:
      required:
        - dateTime
      type: object
      properties:
        dateTime:
          type: string
          format: offset

Furthermore, you can declare the imports inline if you would like, and not worry about the importMappings at all.

<typeMappings>
    <typeMapping>OffsetDateTime=java.time.OffsetDateTime</typeMapping>
    <typeMapping>ZonedDateTime=java.time.ZonedDateTime</typeMapping>
    <typeMapping>LocalDateTime=java.time.LocalDateTime</typeMapping>
</typeMappings>

It's really up to you.