Populating Class[] with JSON in TypeScript - json

Question

As part of my model I have this class in TypeScript:
module App.Model {
export class Unit {
id: number;
participantId: number;
name: string;
isProp: boolean;
}
}
In the controller, I need a a hash with the id as key:
module App.Controllers {
export class MyController {
public units: App.Model.Unit[];
populateDemoData() {
this.units = {
"1": { "id": 1, "participantId": 1, "name": "Testname", "isProp": true },
"2": { "id": 2, "participantId": 1, "name": "Another name", "isProp": false }
};
}
}
}
However, compiling the controller, I get the following error message:
Error 2 Cannot convert '{ }; [n: number]: App.Model.Unit; }' to ' }; [n: number]: App.Model.Unit; }' is missing property 'concat' from type 'App.Model.Unit[]'.
What am I doing wrong? And why is TypeScript asking for a concat property?

Answer 1

You defined units as an Array object, but assigned it a literal object. Just to clarify, a hash (a literal object) is not an array.
If all the IDs are an integer you can still use the array but it would be like this instead:
populateDemoData() {
this.units = [];
this.units[1] = { "id": 1, "participantId": 1, "name": "Testname", "isProp": true };
this.units[2] = { "id": 2, "participantId": 1, "name": "Another name", "isProp": false };
}
Edit:
Ok, you have to define a hash table to do that, but you also need to make App.Model.Unit an interface that matches your JSON objects.
module App.Model {
export interface Unit {
id: number;
participantId: number;
name: string;
isProp: boolean;
}
export interface UnitHashTable {
[id: string]: Unit;
}
}
module App.Controllers {
export class MyController {
public units: App.Model.UnitHashTable;
populateDemoData() {
this.units = {
"1": { "id": 1, "participantId": 1, "name": "Testname", "isProp": true },
"2": { "id": 2, "participantId": 1, "name": "Another name", "isProp": false }
};
}
}
}