[Golang][go-gin-server]can not use the param of the path

[kemokemo]

Description

The path with param does not be generated properly. ex) /pet/{petId}

openapi-generator version

3.3.0-SNAPSHOT
(master)

OpenAPI declaration file content or url

extracted_petstore.yaml

openapi: 3.0.0
servers:
  - url: 'http://petstore.swagger.io/v2'
info:
  description: >-
    This is a sample server Petstore server. For this sample, you can use the api key
    `special-key` to test the authorization filters.
  version: 1.0.0
  title: OpenAPI Petstore
  license:
    name: Apache-2.0
    url: 'http://www.apache.org/licenses/LICENSE-2.0.html'
tags:
  - name: pet
    description: Everything about your Pets
paths:
  '/pet/{petId}':
    get:
      tags:
        - pet
      summary: Find pet by ID
      description: Returns a single pet
      operationId: getPetById
      parameters:
        - name: petId
          in: path
          description: ID of pet to return
          required: true
          schema:
            type: integer
            format: int64
      responses:
        '200':
          description: successful operation
          content:
            application/xml:
              schema:
                $ref: '#/components/schemas/Pet'
            application/json:
              schema:
                $ref: '#/components/schemas/Pet'
        '400':
          description: Invalid ID supplied
        '404':
          description: Pet not found
      security:
        - api_key: []
externalDocs:
  description: Find out more about Swagger
  url: 'http://swagger.io'
components:
  requestBodies:
    Pet:
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Pet'
        application/xml:
          schema:
            $ref: '#/components/schemas/Pet'
      description: Pet object that needs to be added to the store
      required: true
  schemas:
    Pet:
      title: a Pet
      description: A pet for sale in the pet store
      type: object
      required:
        - name
        - photoUrls
      properties:
        id:
          type: integer
          format: int64
        category:
          $ref: '#/components/schemas/Category'
        name:
          type: string
          example: doggie
        photoUrls:
          type: array
          xml:
            name: photoUrl
            wrapped: true
          items:
            type: string
        tags:
          type: array
          xml:
            name: tag
            wrapped: true
          items:
            $ref: '#/components/schemas/Tag'
        status:
          type: string
          description: pet status in the store
          enum:
            - available
            - pending
            - sold
      xml:
        name: Pet

Command line used for generation

generate -i extracted_petstore.yaml -g go-gin-server -o go-gin-server

Steps to reproduce

Related issues/PRs

Issue #1047
PR #1048

Suggest a fix/enhancement

routers.go generated by the current master.

var routes = Routes{
	{
		"Index",
		"GET",
		"/v2/",
		Index,
	},

	{
		"GetPetById",
		strings.ToUpper("Get"),
		"/v2/pet/{petId}",
		GetPetById,
	},
}

This code should be below:

var routes = Routes{
	{
		"Index",
		"GET",
		"/v2/",
		Index,
	},

	{
		"GetPetById",
		strings.ToUpper("Get"),
		"/v2/pet/:petId",
		GetPetById,
	},
}

[kemokemo]

I am sorry that the operation check was insufficient. I'll try fix this.
The {{{path}}} parameter passed to the routers.mustache has to be converted.

I will try to refer to ErlangServerCodegen.java which is doing similar processing.

[kemokemo]

Hmm..
The gin has the specification gin-gonic/gin#388. I did not know until today.
I think that it's their design decision.

By modifying GoGinServerCodegen.java, I can generate the intended code on my local branch.
However, stub code generated from the standard petstore.yaml due to the specification of gin above does not work with the following error.

Server started
[GIN-debug] [WARNING] Now Gin requires Go 1.6 or later and Go 1.7 will be required soon.

[GIN-debug] [WARNING] Creating an Engine instance with the Logger and Recovery middleware already attached.

[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.
 - using env:	export GIN_MODE=release
 - using code:	gin.SetMode(gin.ReleaseMode)

[GIN-debug] GET    /v2/                      --> github.com/kemokemo/go-gin-server/go.Index (3 handlers)
[GIN-debug] POST   /v2/pet                   --> github.com/kemokemo/go-gin-server/go.AddPet (3 handlers)
[GIN-debug] DELETE /v2/pet/:petId            --> github.com/kemokemo/go-gin-server/go.DeletePet (3 handlers)
[GIN-debug] GET    /v2/pet/findByStatus      --> github.com/kemokemo/go-gin-server/go.FindPetsByStatus (3 handlers)
[GIN-debug] GET    /v2/pet/findByTags        --> github.com/kemokemo/go-gin-server/go.FindPetsByTags (3 handlers)
[GIN-debug] GET    /v2/pet/:petId            --> github.com/kemokemo/go-gin-server/go.GetPetById (3 handlers)
panic: wildcard route ':petId' conflicts with existing children in path '/v2/pet/:petId'

The endpoint /v2/pet/findByTags and /v2/pet/:petId are conflict with gin...

Is this disqualified as a generator?

[wing328]

  "/v2/pet/:petId",

The other generators (e.g. finch) has a similar patch to correct the path parameter. Let me know if you need the code snippet to fix the same in the Go Gin generator.

[wing328]

The endpoint /v2/pet/findByTags and /v2/pet/:petId are conflict with gin...

We can document this in the auto-generated README as a known issue with a reference to gin-gonic/gin#388

Users can manually fix it by updating the path to workaround the issue for the time being.

[kemokemo]

@wing328 Thank you so much for your advise!
I am sorry that I caught a cold and the response was delayed.

I will post a PR with the following changes.

• fix the 'the param of the path' issue
• add a known issue and workaround to the README