[BUG] [Go] object nullable not working

[hatappi]

Description

output json using Go struct.
When there is no value in strcut, it may not be displayed in json.
In such a case I will use pointer.

However, if specify nullable: true for the object in the definition file, it will not be output with a pointer.
For integer and string pointers are given.

openapi-generator version

• 3.3.4
• 4.0.0-SNAPSHOT

OpenAPI declaration file content or url

test.yaml

openapi: "3.0.6"
info:
  version: "1.0"
  title: test
paths:
  /test:
    get:
      summary: test
      responses:
        '200':
          description: OK
components:
  schemas:
    user:
      type: object
      properties:
        name:
          type: string
          nullable: true
        age:
          type: integer
          nullable: true
        address:
          type: object
          nullable: true
          properties:
            city:
              type: string

model.mustache

{{>partial_header}}
package {{packageName}}
{{#models}}
{{#imports}}
{{#-first}}
import (
{{/-first}}
	"{{import}}"
{{#-last}}
)
{{/-last}}
{{/imports}}
{{#model}}
{{#isEnum}}
{{#description}}
// {{{classname}}} : {{{description}}}
{{/description}}
type {{{classname}}} {{^format}}{{dataType}}{{/format}}{{#format}}{{{format}}}{{/format}}

// List of {{{name}}}
const (
	{{#allowableValues}}
	{{#enumVars}}
	{{^-first}}
	{{/-first}}
	{{{classname}}}{{name}} {{{classname}}} = "{{{value}}}"
	{{/enumVars}}
	{{/allowableValues}}
){{/isEnum}}{{^isEnum}}{{#description}}
// {{{description}}}{{/description}}
type {{classname}} struct {
{{#vars}}
{{^-first}}
{{/-first}}
{{#description}}
	// {{{description}}}
{{/description}}
	{{name}} {{#isNullable}}*{{/isNullable}}{{dataType}} `json:"{{baseName}}{{^required}},omitempty{{/required}}"{{#withXml}} xml:"{{baseName}}{{#isXmlAttribute}},attr{{/isXmlAttribute}}"{{/withXml}}{{#vendorExtensions.x-go-custom-tag}} {{{.}}}{{/vendorExtensions.x-go-custom-tag}}`
{{/vars}}
}
{{/isEnum}}
{{/model}}
{{/models}}

Command line used for generation

docker run --rm \
  -v ${PWD}:/local \
  openapitools/openapi-generator-cli:v3.3.4 \
  generate \
  -i /local/test.yaml \
  -g go \
  -o /local/pkg \
  -t /local/templates

Steps to reproduce

1. Prepare templates/model.mustache
2. Save OpenAPI declaration file with test.yaml
3. run command
4. check pkg/model_user.go

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[ackintosh]

Hi @hatappi ,

nullable support for the Go generator has been merged into master. please give it a try with latest docker image. 😉

[wing328]

openapi: "3.0.6"
info:
  version: "1.0"
  title: test

Btw, I don't think OAS 3.0.6 has released yet. The latest is "3.0.2": https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md

[hatappi]

@ackintosh @wing328
Thank you for reply.
I tried latest docker image. Image Id is e0c35c5a73f5 and openapi version is 3.0.2
But the pointer did not attach to a struct.

test.yaml

openapi: "3.0.2"
info:
  version: "1.0"
  title: test
paths:
  /test:
    get:
      summary: test
      responses:
        '200':
          description: OK
components:
  schemas:
    user:
      type: object
      properties:
        name:
          type: string
          nullable: true
        age:
          type: integer
          nullable: true
        address:
          type: object
          nullable: true
          properties:
            city:
              type: string

command

docker run --rm \
  -v ${PWD}:/local \
  openapitools/openapi-generator-cli \
  generate \
  -i /local/test.yaml \
  -g go \
  -o /local/pkg

generated model

/*
 * test
 *
 * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
 *
 * API version: 1.0
 * Generated by: OpenAPI Generator (https://openapi-generator.tech)
 */

package openapi

type User struct {
	Name *string `json:"name,omitempty"`
	Age *int32 `json:"age,omitempty"`
	Address UserAddress `json:"address,omitempty"`
}

[kemokemo]

Thank you very much for reporting issue!
I am sorry that confirmation with Issue #1869 was insufficient.
I will investigate.

[kemokemo]

Hmm..
In the fromProperty method of the DefaultCodegen.java, p.getNullable() returns false for the address schema. this link

@wing328 @ackintosh
Sorry, could you please give me any advice?

[ackintosh]

Thanks @kemokemo . Let me check 👀

[ackintosh]

Ah 💡 It is due to InlineModelResolver. (The issue doesn't caused by the Go generator. All generator faces the issue)

openapi-generator/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java

Line 888 in f76dca8

inlineModelResolver.flatten(openAPI);

InlineModelResolver#modelFromProperty() (which is called from its flatten()) resolves inline model user.address to UserAddress but the resolved UserAddress model has no nullable value. 😢

[ackintosh]

I'll file a PR to fix the missing nullable. 😉

[ackintosh]

@hatappi The fix has been merged into master but the docker image latest has not updated yet. please wait a moment. 😌

[hatappi]

@ackintosh
Thank you 😊
I'm looking forward to it.

[ackintosh]

The docker image has been updated. I've verified with the image that the UserAddress is generated as pointer.

type User struct {
        Name *string `json:"name,omitempty"`
        Age *int32 `json:"age,omitempty"`
-        Address UserAddress `json:"address,omitempty"`
+        Address *UserAddress `json:"address,omitempty"`
}

Again thanks for reporting this issue. 👍

[hatappi]

@ackintosh
I also confirmed that it was fixed by 246d3a3f904a docker image 🎉
Thank you for fixed.