[Python] JSON request with body=None produces empty payload

[r4victor]

Description

When sending JSON request with body=None, payload is set to empty string, which is not a valid JSON and violates the definition of Content-Type header. Practically, it prevents requests parsing. The semantically correct payload would be '{}'.

This behaviour is implemented in rest.mustache:

request_body = None
if body is not None:
    request_body = json.dumps(body)
r = self.pool_manager.request(
    method, url,
    body=request_body,
    preload_content=_preload_content,
    timeout=timeout,
    headers=headers)

Swagger-codegen version

2.4.6

Swagger declaration file content or url

swagger: "2.0"
info:
  version: "1.0.0"
  title: "Swagger Petstore"
  
paths:
  /pet/{petId}:
    delete:
      operationId: "deletePet"
      parameters:
      - name: "petId"
        in: "path"
        description: "Pet id to delete"
        required: true
        type: "integer"
        format: "int64"
      responses:
        204:
          description: "Deleted"

Command line used for generation

docker run --rm -v ${PWD}:/local swaggerapi/swagger-codegen-cli generate -l python -i /local/spec.yaml -o /local/swagger_out

Steps to reproduce

Describe a resource with POST, PUT, PATCH, OPTIONS or DELETE method,
Content-Type: application/json and empty body.
Make a request, try to parse its body with JSON parsing library such as python's built-in json.
json.loads(body) raises the error since body is empty string.

Related issues/PRs

3020 - issue and corresponding PR which introduced such a behaviour.

Suggest a fix/enhancement

Replace

request_body = None
if body is not None:
    request_body = json.dumps(body)

With

request_body = '{}'
if body is not None:
    request_body = json.dumps(body)

[IgnatBeresnev]

Any update on this?

We've just come across this problem. Fixable with custom codegen settings, but it'd be nice to have it built-in

[HugoMario]

fixed by #10098, thanks guys for help!