Typescript Errors in Function Pushing Objects to an Array

Question

I am trying to push new objects to an array in my Angular 2 app, but I am running into an issue (which I suspect may be a Typescript type issue, though I'm not certain). This is what the array I'm pushing to looks like:

locations = [
  { city: 'Los Angelas', postalCode: '90001', coordinates: 2321 },
  { city: 'New York', postalCode: '10001', coordinates: 3432 },
];

And here is the function I am using to push new zipcodes to the array with:

  addZipcode(event) {
    this.locations.push({ postalCode: this.newPostalCode });
    this.newPostalCode = '';
    this.addZipInput = false;
    event.preventDefault();
  }

The error I'm getting re: this function is:

Argument of type '{ postalCode: any; }' is not assignable to parameter of type '{ city: string; postalCode: string; coordinates: number; }'. Property 'city' is missing in type '{ postalCode: any; }'.

How can I deal with this issue? Users will be pushing postalCodes, not cities or coordinates. I would think I could push an object of any kind to the array, but it seems typescript is preventing this.

developer033 · Accepted Answer · 2017-02-16 00:59:52Z

3

TypeScript has inferred array type as { city: string; postalCode: string; coordinates: number; }[] , but you are trying to push {postalCode:string} - this is error. If you still want to do this then it is necessary to set appropriate type for location:

  location:any[]
  //or
  interface ILocation {
     city?:string;
     postalCode?:string;
     coordinates?:string;
  }
  location:ILocation[];

edited Feb 16, 2017 at 0:59

developer033

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answered Feb 15, 2017 at 23:44

kemsky

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Comments

artem · Accepted Answer · 2017-02-15 23:43:44Z

1

You can declare locations as array of objects with optional city and coordinates:

type Loc = {city?: string; postalCode: string; coordinates?: number};

let locations: Loc[] = [
  { city: 'Los Angelas', postalCode: '90001', coordinates: 2321 },
  { city: 'New York', postalCode: '10001', coordinates: 3432 },
];

answered Feb 15, 2017 at 23:43

artem

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