[Dart] Fix enum generation

[agilob]

1. Correctly generates Enums
2. minor - fix indentation for mapListFromJson

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@ircecho @swipesight @jaumard @athornz @amondnet

fixes #6727 #4974

Also fixes #3633 by removing default initialization to null.

[agilob]

Dart doesnt support inner classes and test is failing because enum StatusEnum is defined twice in pet.dart and order.dart.

Easy solution to this would be to generate enum name as {{classname}}{{datatypeWithEnum}} so it generates PetStatusEnum. Scala-lagom and nodejs-grapqhl is using it, so I'm not first getting this problem. Considering this also isn't a reusable enum in dart, but class specific, I'm going to go this direction.

[agilob]

Imo this is ready now, @ircecho (2017/07) @swipesight (2018/09) @jaumard (2018/09) @nickmeinhold (2019/09) @athornz (2019/12) @amondnet (2019/12)

@wing328 would it be possible to get this in the next release 5? Is there any specific roadmap?

[wing328]

@wing328 would it be possible to get this in the next release 5? Is there any specific roadmap?

Yes, I think so. We'll release 5.0.0-beta to start with (hopefully this week).

For the roadmap, please refer to https://github.com/OpenAPITools/openapi-generator/blob/master/docs/roadmap.md

[agilob]

@wing328 Fixed conflicts

[agilob]

Found a regression when non-required fields with default value aren't correctly generated.

[agilob]

This fixes not setting null value on properties that don't have default value. Dart is evolving to non-null by default language, so this will be important in the next releases of the language.

[agilob]

@wing328 opening back for review after correctly setting default value and removing null from default values.

https://dart.dev/null-safety

[agilob]

@wing328 can we have this merged please?

[sbu-WBT]

Hi, I tested this PR with this https://github.com/geoDavey/osrm-openapi/blob/master/osrm-openapi.yaml OpenAPI specification.
I'm get still something like this ApiResponseCodeEnum code = ;.
I'm also getting some invalid enum classes:

class IntersectionList<EntryEnum> {
  /// The underlying value of this enum member.
  final List<String> value;

  const IntersectionList<EntryEnum>._internal(this.value);

  static const IntersectionList<EntryEnum> true_ = IntersectionList<EntryEnum>._internal("true");
  static const IntersectionList<EntryEnum> false_ = IntersectionList<EntryEnum>._internal("false");

  List<String> toJson () {
    return value;
  }

  @override
  String toString () {
    return value;
  }

  static IntersectionList<EntryEnum> fromJson(List<String> value) {
    return IntersectionList<EntryEnum>TypeTransformer().decode(value);
  }

  static List<IntersectionList&lt;EntryEnum&gt;> listFromJson(List<dynamic> json) {
    return json == null
        ? List<IntersectionList&lt;EntryEnum&gt;>()
        : json.map((value) => IntersectionList&lt;EntryEnum&gt;.fromJson(value)).toList();
  }
}

class IntersectionList&lt;EntryEnum&gt;TypeTransformer {

  dynamic encode(IntersectionList&lt;EntryEnum&gt; data) {
    return data.value;
  }

  IntersectionList&lt;EntryEnum&gt; decode(dynamic data) {
    switch (data) {
      case "true": return IntersectionList&lt;EntryEnum&gt;.true_;
      case "false": return IntersectionList&lt;EntryEnum&gt;.false_;
      default: return null;
    }
  }
}

Could you have a look over it why it happens? Because some enum classes generation works.
Thanks

[agilob]

I'm get still something like this ApiResponseCodeEnum code = ;.

That's because allOf and anyOf aren't supported, and it worked (by letting code compiled by defaulting to null) by accident. reverted the breaking change.

[wing328]

Tested again and the result looks good.