Nswag: TypeScript: 200 with file and 204 throws exception

[ahmettahasakar]

Hello

If i return a 204 nocontent, the typescript throws a swagger exception. However, it is a successfull return code. blobtotext works and then the pipe throws the exception. Am i missing something?

Thank you

[RicoSuter]

Can you post some sample Swagger spec + TS output?

[ahmettahasakar]

"delete": {
        "tags": [
          "HaileeResponses"
        ],
        "operationId": "HaileeResponses_Delete",
        "parameters": [
          {
            "type": "string",
            "name": "id",
            "in": "path",
            "required": true,
            "format": "guid",
            "x-nullable": false
          }
        ],
        "responses": {
          "200": {
            "x-nullable": true,
            "description": "",
            "schema": {
              "type": "file"
            }
          },
          "204": {
            "description": ""
          },
          "400": {
            "description": "Runtime error",
            "schema": {
              "type": "object",
              "additionalProperties": false,
              "properties": {
                "error": {
                  "$ref": "#/definitions/ErrorViewModel"
                }
              }
            }
          }
        }
      }

delete(id: string): Observable<FileResponse | null> {
        let url_ = this.baseUrl + "/HaileeResponses/{id}";
        if (id === undefined || id === null)
            throw new Error("The parameter 'id' must be defined.");
        url_ = url_.replace("{id}", encodeURIComponent("" + id)); 
        url_ = url_.replace(/[?&]$/, "");

        let options_ : any = {
            observe: "response",
            responseType: "blob",
            headers: new HttpHeaders({
                "Content-Type": "application/json", 
                "Accept": "application/json"
            })
        };

        return this.http.request("delete", url_, options_).pipe(_observableMergeMap((response_ : any) => {
            return this.processDelete(response_);
        })).pipe(_observableCatch((response_: any) => {
            if (response_ instanceof HttpResponseBase) {
                try {
                    return this.processDelete(<any>response_);
                } catch (e) {
                    return <Observable<FileResponse | null>><any>_observableThrow(e);
                }
            } else
                return <Observable<FileResponse | null>><any>_observableThrow(response_);
        }));
    }

    protected processDelete(response: HttpResponseBase): Observable<FileResponse | null> {
        const status = response.status;
        const responseBlob = 
            response instanceof HttpResponse ? response.body : 
            (<any>response).error instanceof Blob ? (<any>response).error : undefined;

        let _headers: any = {}; if (response.headers) { for (let key of response.headers.keys()) { _headers[key] = response.headers.get(key); }};
        if (status === 200 || status === 206) {
            const contentDisposition = response.headers ? response.headers.get("content-disposition") : undefined;
            const fileNameMatch = contentDisposition ? /filename="?([^"]*?)"?(;|$)/g.exec(contentDisposition) : undefined;
            const fileName = fileNameMatch && fileNameMatch.length > 1 ? fileNameMatch[1] : undefined;
            return _observableOf({ fileName: fileName, data: <any>responseBlob, status: status, headers: _headers });
        } else if (status === 204) {
            return blobToText(responseBlob).pipe(_observableMergeMap(_responseText => {
            return throwException("A server error occurred.", status, _responseText, _headers);
            }));
        } else if (status === 400) {
            return blobToText(responseBlob).pipe(_observableMergeMap(_responseText => {
            let result400: any = null;
            let resultData400 = _responseText === "" ? null : JSON.parse(_responseText, this.jsonParseReviver);
            result400 = resultData400 ? Anonymous7.fromJS(resultData400) : new Anonymous7();
            return throwException("A server error occurred.", status, _responseText, _headers, result400);
            }));
        } else if (status !== 200 && status !== 204) {
            return blobToText(responseBlob).pipe(_observableMergeMap(_responseText => {
            return throwException("An unexpected server error occurred.", status, _responseText, _headers);
            }));
        }
        return _observableOf<FileResponse | null>(<any>null);
    }

[RicoSuter]

Ah, I think 200 with file + 204 is a special case and may not be correctly handled at the moment...

[ahmettahasakar]

There is no file though. I am not sure why it thinks that. I didnt add 200+file either

[RicoSuter]

Can you post the C# controller operation signature?

[ahmettahasakar]

[HttpDelete("{id:guid}")]
        public async Task<IActionResult> Delete(Guid id)
        {
            var entity = _haileeService.GetHaileeResponseOperation(id);
            if (entity == null)
            {
                return NotFoundWithMessage($"Hailee Response Operation not found {id}");
            }
            await _haileeService.DeleteHaileeResponse(id);
            return NoContent();
        }

and i have a IOperationProcessor as below to add the responses as mentioned in #1353

public class SwaggerResponseTypeAppender : IOperationProcessor
    {
        public async Task<bool> ProcessAsync(OperationProcessorContext context)
        {
            var methodResponse = context.MethodInfo.GetCustomAttributes<ProducesResponseTypeAttribute>();
            if (context.OperationDescription.Method != SwaggerOperationMethod.Delete && !methodResponse.Any())
            {
                throw new ApiException(MyExceptionType.MissingResponseType, context.OperationDescription.Operation.OperationId);
            }

            if (context.OperationDescription.Method == SwaggerOperationMethod.Put || context.OperationDescription.Method == SwaggerOperationMethod.Post)
            {
                await AddResponse(context, HttpStatusCode.UnprocessableEntity, typeof(ValidationFailedResultViewModel));
            }

            if (context.OperationDescription.Method == SwaggerOperationMethod.Get || context.OperationDescription.Method == SwaggerOperationMethod.Put)
            {
                await AddResponse(context, HttpStatusCode.NotFound, null);
            }

            if (context.OperationDescription.Method == SwaggerOperationMethod.Delete)
            {
                await AddResponse(context, HttpStatusCode.NoContent, null);
            }

            await AddResponse(context, HttpStatusCode.BadRequest, typeof(MyExceptionResultViewModel));

            return await Task.FromResult(true);
        }

        private async Task AddResponse(OperationProcessorContext context, HttpStatusCode httpStatusCode, Type type)
        {
            if (type != null && !context.SchemaResolver.HasSchema(type, false))
            {
                await context.SchemaGenerator.GenerateAsync(type, null, context.SchemaResolver);
            }
            var response = new SwaggerResponse();
            if (type != null)
            {
                response.Schema = context.SchemaResolver.GetSchema(type, false);
            }
            switch (httpStatusCode)
            {
                case HttpStatusCode.UnprocessableEntity:
                    response.Description = "Validation error";
                    break;
                case HttpStatusCode.BadRequest:
                    response.Description = "Runtime error";
                    break;
                case HttpStatusCode.NotFound:
                    response.Description = "Record not found error";
                    break;
            }
            int httpCode = (int)httpStatusCode;
            var kvp = new KeyValuePair<string, SwaggerResponse>(httpCode.ToString(), response);
            context.OperationDescription.Operation.Responses.Add(kvp);
        }
    }

[RicoSuter]

A result of IActionResult automatically adds a 200 file response. You can change that with the [SwaggerResponse] attribute (see docs)

[ahmettahasakar]

I see, can i remove it with IOperationProcessor?

[RicoSuter]

Yes

[ahmettahasakar]

When I removed 200 from via IOperationProcessor, then the problem is fixed.

New generated code is below, and it doesn't throw exception

    protected processDelete(response: HttpResponseBase): Observable<void> {
        const status = response.status;
        const responseBlob = 
            response instanceof HttpResponse ? response.body : 
            (<any>response).error instanceof Blob ? (<any>response).error : undefined;

        let _headers: any = {}; if (response.headers) { for (let key of response.headers.keys()) { _headers[key] = response.headers.get(key); }};
        if (status === 204) {
            return blobToText(responseBlob).pipe(_observableMergeMap(_responseText => {
            return _observableOf<void>(<any>null);
            }));
        } else if (status === 400) {
            return blobToText(responseBlob).pipe(_observableMergeMap(_responseText => {
            let result400: any = null;
            let resultData400 = _responseText === "" ? null : JSON.parse(_responseText, this.jsonParseReviver);
            result400 = resultData400 ? Anonymous7.fromJS(resultData400) : new Anonymous7();
            return throwException("A server error occurred.", status, _responseText, _headers, result400);
            }));
        } else if (status !== 200 && status !== 204) {
            return blobToText(responseBlob).pipe(_observableMergeMap(_responseText => {
            return throwException("An unexpected server error occurred.", status, _responseText, _headers);
            }));
        }
        return _observableOf<void>(<any>null);
    }

[FabianTe]

I encountered the same problem but I can't remove the ProducesResponseType 200 attribute.
How can I solve or workaround this? 🤔

Edit: I am not dealing with a file. This is the part of my swagger.json:

"responses": {
    "200": {
        "description": "Success",
        "schema": {
            "type": "array",
            "items": {
            "$ref": "#/definitions/Incident"
            }
        }
    },
    "204": {
        "description": "Success"
    },
    "401": {
        "description": "Unauthorized: Authentication not valid",
        "schema": {
            "$ref": "#/definitions/Indicents",
            "type": "Indicents",
            "example": {
                // ...
            }
        }
    },
    "404": {
        "description": "Not Found"
    },
    "500": {
        "description": "Internal Server Error: A major internal server problem occurred",
        "schema": {
            "$ref": "#/definitions/Indicents",
            "type": "Indicents",
            "example": {
                // ...
            }
        }
    }
},

[FabianTe]

@RSuter I tried creating a workaround for this. In TS it is possible to "just" return everything all 2xx return codes have responded. This is my change: https://github.com/FabianTe/NSwag/commit/7d1ea538281c77d3b5882e52bba8a761a61b9c55

Edit: I figured out my local problem. This fix works and I'll submit it.

[RicoSuter]

@FabianTe please create a PR so that we can look into it and review it...

[nealsu]

I have a similar issue where my .net core API returns:
NoContent() to a Task<IActionResult> controller method response when the search provides no results.
Ok(result) when there are search results.

Which has the following attribute:
[ProducesResponseType(StatusCodes.Status204NoContent)]
[ProducesResponseType(typeof(IEnumerable<SearchResponse>), StatusCodes.Status200OK)]

And produces an exception on receiving a 204, which is very unexpected behaviour. Note the explicit 204 exception block.

if (status === 500) {
    return response.text().then((_responseText) => {
    return throwException("Server Error", status, _responseText, _headers);
    });
} else if (status === 204) {
    return response.text().then((_responseText) => {
    return throwException("Success", status, _responseText, _headers);
    });
} else if (status === 200) {
    return response.text().then((_responseText) => {
    let result200: any = null;
    let resultData200 = _responseText === "" ? null : JSON.parse(_responseText, this.jsonParseReviver);
    if (Array.isArray(resultData200)) {
        result200 = [] as any;
        for (let item of resultData200)
            result200!.push(SearchResponse.fromJS(item));
    }
    return result200;
    });
} else if (status !== 200 && status !== 204) {
    return response.text().then((_responseText) => {
    return throwException("An unexpected server error occurred.", status, _responseText, _headers);
    });
}

[jeremyVignelles]

Related to #2995 and #1259

[nealsu]

Thanks @jeremyVignelles , do you think it is still related if the controller method has both attributes:

[ProducesResponseType(typeof(IEnumerable<SearchResponse>), StatusCodes.Status200OK)]
and
[ProducesResponseType(StatusCodes.Status204NoContent)]

Is this valid and should the nswag client manage that? I'll have a look at the other tickets and maybe repost there.
The above is supposed to cater for a search that produces no results.

[jeremyVignelles]

I'd argue that an empty response should return 200 with [], but there are probably APIs out there that work that way (can return both 200 and 204 without content).
I think that for those cases, the 204 should map to a null result. and should not throw.