Axios: generator does not seem to support multiple response types #1588

[ajubin]

Description

If you use an openAPI schema with multiple responses like this:

  "/api/user": {
    "get": {
      "operationId": "get_user",
      "summary": "Get User",
      "parameters": [],
      "responses": {
        "200": {
          "description": "OK",
          "content": {
            "application/json": {
              "schema": { "$ref": "#/components/schemas/UserResponse" }
            }
          }
        },
        "400": {
          "description": "Bad Request",
          "content": {
            "application/json": {
              "schema": { "$ref": "#/components/schemas/ApiErrorResponse" }
            }
          }
        }

The generated fetch will only have the 200 response type (in this example UserResponse). It does not seem to generate a union type for the method return type.

Expected Solution

There was a similar issue with fetch that was solved

• the issue
• the fix

Current Workaround

I provide my own response type, but I manually typed it (instead of using openapi spec)

export const customClient = <T>(
  config: AxiosRequestConfig,
  maybeOptions?: AxiosRequestConfig,
): Promise<ReponseType<T>> => {

          // ... implementation
}

type ReponseType<TRes> = AxiosResponse<
  | TRes
  | {
      status: 400;
      statusText: string;
      data: {
        message: {
          name: string;
          message: string;
          statusCode: 400;
          errorLevel: string;
          context: object;
        };
      };
    }
>;

[melloware]

@ajubin isn't that documented here: https://orval.dev/guides/custom-axios

so in my demo app all of my 4xx and 5xx errors return an HttpProblem response which I map with 1 line of Axios here: https://github.com/melloware/quarkus-primereact/blob/e6c2317a77deb969a6f41967072c6f5a7da80d38/src/main/webui/src/service/AxiosMutator.ts#L26

my HttpProblem was generated by Orval: https://github.com/melloware/quarkus-primereact/blob/e6c2317a77deb969a6f41967072c6f5a7da80d38/src/main/webui/src/service/CarService.ts#L80-L95

[ajubin]

well for now I have something similar than you, but it's still a limitation compared to the fetch client. Indeed, we have a type that is not route specific

Let me take another example, I have a route POST /car that create a car and have the following response:

• 201: created
• 412 (precondition not met, specific to this route): containing a body explaining what is missing

For other routes, I never have 412.

I'd love to have something like that generated

// generated-client.ts

type PostCarResponse = CarCreatedResponse | Car412Response

[melloware]

Interesting. Yeah I wasn't sure if this was some limitation but it looks like Orval has always done this for Axios and the Fetch client was written more recently. @anymaniax will know the history of it?