When the response code is 204, it tries to de-serialize an empty body

[MagnusJohansson]

Hi,

given an APi endpoint that responds with either a 200 or 204 (Non content)

    "responses": {
                    "200": {
                        "description": "Success",
                        "content": {
                            "text/plain": {
                                "schema": {
                                    "$ref": "#/components/schemas/MarketingDocumentContract"
                                }
                            },
                            "application/json": {
                                "schema": {
                                    "$ref": "#/components/schemas/MarketingDocumentContract"
                                }
                            },
                            "text/json": {
                                "schema": {
                                    "$ref": "#/components/schemas/MarketingDocumentContract"
                                }
                            }
                        }
                    },
                    "204": {
                        "description": "No Content"
                    },
                    "400": {
                        "description": "Bad Request",
                        "content": {
                            "text/plain": {
                                "schema": {
                                    "$ref": "#/components/schemas/ValidationProblemDetails"
                                }
                            },
                            "application/json": {
                                "schema": {
                                    "$ref": "#/components/schemas/ValidationProblemDetails"
                                }
                            },
                            "text/json": {
                                "schema": {
                                    "$ref": "#/components/schemas/ValidationProblemDetails"
                                }
                            }
                        }
                    }
                }

The generated code will try to de-serialize an empty body (the last line):

 ///
  ///
  /// Download a marketing PDF
  Future<MarketingDocumentContract> generateMarketingPdf(
      {Options? options,
      MarketingDocumentRequestContract?
          marketingDocumentRequestContract}) async {
    final response = await apiDelegate.generateMarketingPdf(
        options: options,
        marketingDocumentRequestContract: marketingDocumentRequestContract);

    if (![200, 204, 400].contains(response.statusCode)) {
      throw ApiException(500,
          'Invalid response code ${response.statusCode} returned from API');
    }

    final __body = response.body;
    if (response.statusCode >= 400) {
      throw ApiException(response.statusCode,
          __body == null ? null : await decodeBodyBytes(__body));
    }

    if (__body == null) {
      throw ApiException(500, 'Received an empty body (not in a 204)');
    }

    return await apiDelegate.generateMarketingPdf_decode(__body);
  }

  ///
  ///
  /// Download a marketing PDF
}

Which will result in:

[log] FormatException: Unexpected end of input (at character 1)
      
      ^
E/flutter ( 7505): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: FormatException: Unexpected end of input (at character 1)
E/flutter ( 7505):
E/flutter ( 7505): ^
E/flutter ( 7505):
E/flutter ( 7505): #0      _ChunkedJsonParser.fail (dart:convert-patch/convert_patch.dart:1405:5)
E/flutter ( 7505): #1      _ChunkedJsonParser.close (dart:convert-patch/convert_patch.dart:523:7)
E/flutter ( 7505): #2      _parseJson (dart:convert-patch/convert_patch.dart:41:10)
E/flutter ( 7505): #3      JsonDecoder.convert (dart:convert/json.dart:612:36)
E/flutter ( 7505): #4      JsonCodec.decode (dart:convert/json.dart:216:41)
E/flutter ( 7505): #5      jsonDecode (dart:convert/json.dart:155:10)
E/flutter ( 7505): #6      LocalApiClient.deserializeFromString

[rvowles]

Hrm - when you are returning 3 different things from one API, you shouldn't really use this method. Dart doesn't have the capability like Typescript where you can return multiple different types from one function. I would recommend as a workaround that you just use the apiDelegate directly (it is exposed for just this kind of use case).

To better support this kind of use case, I should really be returning a generated class which holds all the possible return types.