数组中的泛型类型？

Question

I was trying to create a mockup app that shows some data as a list of buttons. I implemented everything but I'm facing this problem right now. I initialised an array and another class for the data.

-items.ts

  export class ItemPage {

  items: Item[] = [];

  constructor() {

    this.items.push(
      new Item(1, 'Apple', 'Green', 6, true));
    this.items.push(
      new Item(2, 'Banana', 'Yellow', 15, false));
  }

and the data class looks like this

-item.ts

export class Item {
  constructor(
    id: number,
    fruit: string,
    color: string,
    quantity: number,
    onStock: boolean,
  ) { }
}

I'm facing a problem with items: Item[] = []; when I run ionic serve . It says Generic type 'Item' requires 2 type argument(s) and type Item<K extends string, T> = { [P in K]: T; } Construct a type with a set of properties K of type T type Item<K extends string, T> = { [P in K]: T; } Construct a type with a set of properties K of type T .
I tried to solve it but it didn't help, does anyone has any Idea how to solve this?

Thanks

Answer 1

I didn't exactly manage to reproduce the issue, but instead ending up with two empty objects. The error seems that you are not setting the properties in your class as public , so changing your class to:

export class Item {
  constructor(
    public id: number,
    public fruit: string,
    public color: string,
    public quantity: number,
    public onStock: boolean,
  ) { }
}

seemed to work fine: Plunker

BUT I highly suggest you should use interfaces instead, if you don't need to have functions in classes or some other reason. So I'd say you make interface:

export interface Item {
  id: number;
  fruit: string;
  color: string;
  quantity: number;
  onStock: boolean;
}

constructor(private navController: NavController) {
  this.items.push({id:1, fruit:'Apple', color:'Green', quantity:6, onStock:true});
  this.items.push({id:2, fruit: 'Banana',color:'Yellow',quantity:15,onStock:false})
}

Hopefully this helps!