Serialize JSON to enum.

[sagarnayak]

I would like to convert a string to an enum type. lets say i have a enum.

enum Test{
YES="1",
NO="0"
}

and when i get {"value":"1"} from server i want to have YES in my typescript class not 1. is it possible?

[andreas-aeschlimann]

Yes, of course.

You need to check out the example of „custom converters“ in the ReadMe. If you follow this example, you should have no problems implementing your request.

[sagarnayak]

I was also thinking of that approach. but if you have worked with java you might know that we can just add the @SerializedName attribute to the enum constants. and it will auto parse from json according to its type and value.
I was expecting something like that.
anyways thanks for the help.

[andreas-aeschlimann]

json2typescript is as small as it can be. Therefore, no "magic" is happening under the hood. It could be possible that we support such a deserialization by default at some point, but for now you may easily implement it for yourself.

[Almar]

Hi all,
I wrote the following enum converter base class to help me out.

  export class EnumConverter<T> implements JsonCustomConvert<T> {
    validValues: string[];

    constructor(private enumType: unknown, private enumName: string) {
      this.validValues = Object.values(Object.getOwnPropertyDescriptors(enumType)).map(
        (value) => value.value
      );
    }

    deserialize(value: string): T {
      if (!this.validValues.includes(value)) {
        throw new Error(
          `JsonConvert error; invalid value for enum ${this.enumName}, expected one of '${this.validValues}', found '${value}'`
        );
      }
      return (value as unknown) as T;
    }

    serialize(data: T): any {
      return data;
    }
  }

Usage:

enum MyEnum {
  RED = "red",
  WHITE = "white",
  BLUE = "blue",
}

@JsonConverter
class MyEnumConverter extends EnumConverter<MyEnum> {
  constructor() {
    super(MyEnum, "MyEnum");
  }
}

[andreas-aeschlimann]

Thank you @Almar, very cool. Do you like to make a PR or shall I implement it occasionally?

[Almar]

Hey @andreas-aeschlimann,
It would be cool if I can contribute via a PR. I'll give it a try ;-)

[andreas-aeschlimann]

Nice! Please try to add some tests as well for enums.