Cannot deserialize to a class with a constructor that takes an enum

[Lars-Sommer]

I have this enum:

@JsonSerializable()
enum EActionType { None, Installation, Replacement }

I Have this class:

@JsonSerializable()
class TestModel {
  EActionType type = EActionType.None;
}

I have this json:

var json = {
      'type': 'Installation',
}

Deserializing this works just fine 👌

But I need a constructor in my class to instantiate the model in my code logic:

@JsonSerializable()
class TestModel {
  EActionType type = EActionType.None;

  TestModel(EActionType actionType) {
    type = actionType;
  }
}

Now the deserializing fails with: TypeError (type 'Null' is not a subtype of type 'EActionType')

If I remove the actionType, so the constructor is empty, the deserialization works fine.

Any clues? 🤔

[k-paxian]

well, that should be the easy one, it's not obvious that constructor parameter actionType needs to be mapped to json field type, so you should tell it explicitly how to operate:

@JsonSerializable()
class TestModel {
  EActionType type = EActionType.None;

  TestModel(@JsonProperty(name: 'type') EActionType actionType) {
    type = actionType;
  }
}

This should do the trick, if not let me know.

In your case you have different field names, but there are more cases around that, like:

• when the class field names matched to json fields it's an auto-mapping, obvious one so it works right away
• the class has read-only field type and you can set it via constructor only, but you are giving constructor parameter same name type that case is not resolved automagically yet 😄

@jsonSerializable
class Model {
  EActionType _type = EActionType.None;
  EActionType get type {
    return _type;
  }

  Model(EActionType  type) {
    _type = type;
  }
}

[Lars-Sommer]

Makes great sense, and it works ofc :) Thanks alot! 🍺

[k-paxian]

Wow, so generous, thank you so much appreciate that. All I can do for you is my pleasure, challenge me whenever you like

[Lars-Sommer]

This library is priceless, and your ability to help and sort out issues so fast is incredible!