[BUG] [dart-dio] Cannot convert Date type using json_serializer

[AAkira]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

The dart-dio doesn't convert the Date type using json_serializer but the dart-dio can convert the Date type using built_value.

openapi-generator version

v6.5.0

OpenAPI declaration file content or URL

• openapi.yaml

...
        binary:
          description: None
          format: binary
          type: string
        date:
          description: None
          format: date
          type: string
        dateTime:
          description: None
          format: date-time
          type: string
...

Generation Details

• samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/api/fake_api.dart

...

 Future<Response<void>> testEndpointParameters({ 
    required num number,
    required double double_,
    required String patternWithoutDelimiter,
    required String byte,
    int? integer,
    int? int32,
    int? int64,
    double? float,
    String? string,
    MultipartFile? binary,
    DateTime? date,                     // <= Scheme type is Date but here is DateTime.
    DateTime? dateTime,
    String? password,
    String? callback,
    CancelToken? cancelToken,
    Map<String, dynamic>? headers,
    Map<String, dynamic>? extra,
    ValidateStatus? validateStatus,
    ProgressCallback? onSendProgress,
    ProgressCallback? onReceiveProgress,
  }) async {
    final _path = r'/fake';

...

Suggest a fix

Conversion of the Date type is only with bulit_value.

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartDioClientCodegen.java#L298-L304

[ChristianVaughn]

Correct me if im wrong but I don't think dart has a Date type built in, and that's why it is using DateTime. The built-in types are visible here. https://api.dart.dev/stable/2.19.6/dart-core/dart-core-library.html

[AAkira]

Yes.
Dart does not have a Date type.

However, there is a problem when using DateTime with OpenApi.
OpenApi uses toString() to convert parameters to JSON when sending them to the server.
If you use DateTime as is, it will be in this format "$y-$m-${d}T$h:$min:$sec.${ms}Z", which will cause a validation error on the server side.

https://chromium.googlesource.com/external/dart/+/master/dart/sdk/lib/core/date_time.dart#517

And the built_value supports a Date type.

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/built_value/date.mustache

[ahmednfwela]

@jaumard (2018/09) @josh-burton (2019/12) @amondnet (2019/12) @sbu-WBT (2020/12) @kuhnroyal (2020/12) @agilob (2020/12) @ahmednfwela (2021/08)

[kuhnroyal]

This is just not implemented, would you like to create a PR?
See google/json_serializable.dart#133

[hungify]

Any updates? I'm having a problem, as @AAkira mentioned.
I tried to change the template, but it didn't work, and I also switched to timemachine instead of core, but it caused an error.

Could not generate `fromJson` code for `shipDate`.
To support the type `OffsetDateTime` you can:
* Use `JsonConverter`
  https://pub.dev/documentation/json_annotation/latest/json_annotation/JsonConverter-class.html
* Use `JsonKey` fields `fromJson` and `toJson`
  https://pub.dev/documentation/json_annotation/latest/json_annotation/JsonKey/fromJson.html
  https://pub.dev/documentation/json_annotation/latest/json_annotation/JsonKey/toJson.html
package:apiService/src/model/order.dart:79:25
   ╷
79 │   final OffsetDateTime? shipDate;