Swagger-codegen: TypeScript Fetch client doesn't support multipart/form-data body

[janslow]

Description

If a POST operation accepts multipart/form-data, the typescript-fetch client posts an application/x-www-form-urlencoded body instead of form data.

Swagger-codegen version

Version currently deployed on [editor.swagger.io]

Swagger declaration file content or url

swagger: '2.0'
info: { version: 0.1.0, title: Multipart Upload }
paths:
  /:
    post:
      operationId: upload
      consumes:
        - multipart/form-data
      parameters:
        - name: file
          in: formData
          required: true
          type: file
      responses: { '200': { description: Successful upload } }

Command line used for generation

"Generate Client" -> "TypeScript Fetch" on [editor.swagger.io]

Steps to reproduce

1. Generate and compile the sample config
2. Call it with a file
3. Log the request, it has a Content-Type of application/x-www-form-urlencoded instead of multipart/form-data.
   

   Suggest a Fix

Instead of setting the Content-Type and using querystring to serialize the contents (for multipart/form-data requests), it should just set the body to an instance of FormData instead of

e.g., in DefaultApiFetchParamCreactor#upload, instead of :

let contentTypeHeader: Dictionary<string>;
contentTypeHeader = { "Content-Type": "application/x-www-form-urlencoded" };
fetchOptions.body = querystring.stringify({ 
  "file": params.file,
});
if (contentTypeHeader) {
  fetchOptions.headers = contentTypeHeader;
}

it should generate (as Content-Type is set to multipart/form-data automatically if using FormData):

const formData = new FormData();
formData.append("file", params.file);
fetchOptions.body = formData;

[wing328]

@janslow thanks for reporting the issue. May I know if you've time to contribute the fix?

[russtacular]

@wing328 I actually ran into the same issue myself and was in the process of putting together a PR for this and #4153

I can try to pull something together in the next few days, if that's useful for you and @janslow

[bvwells]

Just wondering whether there is any update with this issue?

[Alexuy]

Hey, guys! What about this issue? When you planning to fix that bug?

@wing328 @russtacular

[Splash34]

+1