I have an array like this:
Model:
export class Total {
Id: number;
Products: string;
LastUpdated: Date;
}
I have a list of this with:
myList[] = this.service.getProducts().toPromise();
How do I make a new array with only get Products and LastUpdated from myList?
myProducts[] = ["prod1","prod2","prod3","prod3"];
myDates[] = ["2020-03-01","2020-03-02","2020-03-05","2020-03-06"];
Use map() function. Try the following
const myProducts = this.myList.map(item => item.Products);
const myDates = this.myList.map(item => item.LastUpdated);
const [myProcucts, myDates] = this.myList.reduce((total, item) => { total.push([item.Products, item.LastUpdates]) return total }, [] as Array<string[], Date[]>);
I assume that here this.service.getProducts().toPromise(); gives you type Promise<Total[]> (not an array) so you would write myList instead of myList[].
This way, for products and dates its better/saftier to keep them like Promise<string[]> type.
const myProducts = this.myList.then(list => list.map(item => item.Products));
const myDates = this.myList.then(list => list.map(item => item.LastUpdated));
If you are sure that you need string[] type, you can wait for this promise:
this.myList.then(list => {
this.myProducts = list.map(item => item.Products);
this.myDates = list.map(item => item.LastUpdated);
});
Using mapyou could achieve the result, but you would need to iterate through the entire array twice, which might be bad on large arrays...
So you can use reduce instead.
const [myProcucts, myDates]: [string[], Date[]] = this.myList.reduce((total: [string[], Date[]], item: Total) => {
// push product value to the array of Products
total[0].push(item.Products);
// push lastUpdated value to the array of lastUpdated
total[1].push(item.LastUpdated);
return total
}, [[],[]]);