How do I initialize a TypeScript object with a JSON object

Question

I receive a JSON object from an AJAX call to a REST server. This object has property names that match my TypeScript class (this is a follow-on to this question).

Wha

Answer 1

I've created a tool that generates TypeScript interfaces and a runtime "type map" for performing runtime typechecking against the results of JSON.parse: ts.quicktype.io

For example, given this JSON:

{
  "name": "David",
  "pets": [
    {
      "name": "Smoochie",
      "species": "rhino"
    }
  ]
}

quicktype produces the following TypeScript interface and type map:

export interface Person {
    name: string;
    pets: Pet[];
}

export interface Pet {
    name:    string;
    species: string;
}

const typeMap: any = {
    Person: {
        name: "string",
        pets: array(object("Pet")),
    },
    Pet: {
        name: "string",
        species: "string",
    },
};

Then we check the result of JSON.parse against the type map:

export function fromJson(json: string): Person {
    return cast(JSON.parse(json), object("Person"));
}

I've left out some code, but you can try quicktype for the details.