Type gql-tag in TypeScript

问题:

I am working with GraphQL and I want to have strict typing in gql. Is it possible to make result variable to be shape of ResultData i.e. with the latest version of TypeScript. It is only about typing, not about runtime.

interface Data {
    one: string;
    two: number;
    three: {
        four: string;
        five: {
            six: Date;
        };
    };
}

// true means that this field must be added to query
type RecursivePartial<T> = {[P in keyof T]?: RecursivePartial<T[P]> | true};

function gql<T>(fields: RecursivePartial<T>) {
  // Some code about generating GraphQL query
}

const result = gql<Data>({one: true, three: {five: {six: true}}});

// type ResultData {
//     one: string;
//     three: {
//         five: {
//             six: Date;
//         };
//     };
// }

回答1:

This is working for me in the playground:

interface Data {
    one: string;
    two: number;
    three: {
        four: string;
        five: {
            six: Date;
        };
    };
}

// Prevent widening of true to boolean in queries
type RecursivePartial1 = { [k: string]: RecursivePartial1 | true };
// true means that this field must be added to query
type RecursivePartial<T> = RecursivePartial1 & { [P in keyof T]?: RecursivePartial<T[P]> | boolean };

type RecursivePick<T, Q extends RecursivePartial<T>> =
  { [P in keyof T & keyof Q]:
    Q[P] extends RecursivePartial<T[P]> ? RecursivePick<T[P], Q[P]> : T[P] };

function gql<T, Q extends RecursivePartial<T>>(data: T, fields: Q): RecursivePick<T, Q> {
  // Some code about generating GraphQL query
}

declare const data: Data;
const result = gql(data, { one: true, three: { five: { six: true } } });

// type ResultData {
//     one: string;
//     three: {
//         five: {
//             six: Date;
//         };
//     };
// }