[Java] add missing nullable judgement when required property is true

[fanqiewanzi]

fix #18516

• Add judgment for nullable field to the required judgment.
• Add test for java okhttp-gson template to avoid regressions

Tests:
openapi.yaml

openapi: 3.0.3
info:
  title: test
  description: Test API
  version: 1.0.1

paths:
  /test:
    get:
      responses:
        200:
          description: Valid response
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/SomeObject"

components:
  schemas:
    SomeObject:
      type: object
      required: 
        - ids
        - users
        - user
        - role
        - custom
      properties:
        ids:
          type: array
          nullable: true
          items:
            type: integer
        users:
          type: array
          nullable: true
          items:
            type: object
            properties:
              id:
                type: string
        user:
          type: object
          nullable: true
          properties:
            id:
              type: string
        role:
          type: string
          nullable: true
          enum:
            - admin
            - tenant
        custom:
          $ref: "#/components/schemas/customEnum"
    customEnum:
      type: string
      nullable: true
      enum:
        - custom    

run following command to generate:
openapi-generator-cli generate -i openapi.yaml -o test -g java

And the code compiled successfully.

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[wing328]

thanks for the fix and the test.

shall the new condition {{#isNullable}} && !jsonObj.get("{{baseName}}").isJsonNull(){{/isNullable}} be put in its own code block instead of adding to the JSON array type check as the error message right below only mentions expecting the field to be an array?

[fanqiewanzi]

thanks for the fix and the test.

shall the new condition {{#isNullable}} && !jsonObj.get("{{baseName}}").isJsonNull(){{/isNullable}} be put in its own code block instead of adding to the JSON array type check as the error message right below only mentions expecting the field to be an array?

Hi, I don't quite understand. It doesn't seem to make sense to bring up the nullable judgment alone, because nullable is just an auxiliary judgment. If we put in its own code block, the nullable judgment is set outside the original judgment. From the code point of view, the logic is the same. If you write a judgment to nullable alone to throw an exception, the whole logic will seem even more strange.

     {{^isNullable}}
      if (jsonObj.get("{{baseName}}").isJsonNull()) {
        // throw exception here 
      }
      {{/isNullable}}
      // we will get an exception in the next judgement if json element is null
      // ensure the json data is an array
      if (!jsonObj.get("{{{baseName}}}").isJsonArray()) {
        throw new IllegalArgumentException(String.format("Expected the field `{{{baseName}}}` to be an array in the JSON string but got `%s`", jsonObj.get("{{{baseName}}}").toString()));
      }

Or this is the change you want.

{{#isNullable}} 
if  (!jsonObj.get("{{baseName}}").isJsonNull()) {
  // ensure the json data is an array
        if (!jsonObj.get("{{{baseName}}}").isJsonArray()) {
          throw new IllegalArgumentException(String.format("Expected the field `{{{baseName}}}` to be an array in the JSON string but got `%s`", jsonObj.get("{{{baseName}}}").toString()));
        }
}
{{/isNullable}}

[wing328]

can you please PM me via Slack when you've time?

https://join.slack.com/t/openapi-generator/shared_invite/zt-12jxxd7p2-XUeQM~4pzsU9x~eGLQqX2g

[fanqiewanzi]

ok👌

[marceljk]

Hi @wing328 @fanqiewanzi,

I have the exact same issue where validateJsonElement() throws an error for required nullable properties. I was about to contribute a fix myself when I found this PR and issue #18516.

Since this PR has been open for a while, is there anything specific blocking it? I would be happy to help by resolving any merge conflicts or open a fresh PR, if that would be easier to review.

[wing328]

@marceljk can you please submit a new one based on this one with resolved merge conflicts?

i'll try to get it merged before the upcoming release scheduled next week

[marceljk]

@wing328 I create a new one based on this one with the resolved merge conflicts #22912.

Please let me know if something else is needed

[wing328]

@fanqiewanzi please give it a try with the latest master as we've merged #22912 🙏