index.ts
The interface EntityMap helps make the Generic simpler, and we can reference the class instance types with the keys (strings).
Remember that interfaces are "open" and can be augmented across multiple files in a project.
interface EntityMap {
book: Book;
movie: Movie;
song: Song;
}
// In TS need to use "kind" b/c "type" is a protected name
class Store {
get<K extends keyof EntityMap>(kind: K, id: string): EntityMap[K] {
let foo: any = {};
return foo as EntityMap[K];
}
getAll<K extends keyof EntityMap>(kind: K): EntityMap[K][] {
let foo: any = {};
return foo as EntityMap[K][];
}
create<K extends keyof EntityMap>(kind: K, toCreate: EntityMap[K]): void {}
update<K extends keyof EntityMap>(
kind: K,
id: string,
toUpdate: Partial<EntityMap[K]>
): void {}
}
// Create a store
const store = new Store();
// All the store method have type safety by using the "kind" key string
// You'll have full intellisense in usage
store.get('book', '123');
store.get('movie', '456');
store.getAll('movie');
store.create('song', { musician: 'John Doe', year: 2022 });
store.update('book', '123', { title: 'Foo Bar' });book.ts
class Book {
constructor(public author: string, public title: string) {}
}
interface EntityMap {
book: Book;
}movie.ts
class Movie {
constructor(public director: string) {}
}
interface EntityMap {
movie: Movie;
}song.ts
class Song {
constructor(public musician: string, public year: number) {}
}
interface EntityMap {
song: Song;
}From the Intermediate TypeScript↗ course on FEM↗ taught by Mike North↗.