How to select distinct property values of a list of object in Angular

Question

I have the below list of object:

var data = [
    {
        "AcctId": 100,
        "Value": true
    },
    {
        "AcctId": 200,
        "Value": false
    }
]

I want to select distinct AcctId like this:

Output: [100, 200]

I've tried to use the angular filter method:

var newData = data.filter(r => r.AcctId);

But, it's returning the same list as input. can anyone please guide me on what I'm doing wrong?

Answer 1

Try like this:

Working Demo

this.result = Array.from(new Set(this.data.map(x => x.acctId)));

or,

 constructor() {
    this.result = this.GetDistinctValues(this.data, "acctId").map(x => x.acctId);
  }

  GetDistinctValues(Source: Array<any>, FilterKey: string = null): Array<any> {
    let DistinctArray = [];
    try {
      Source.forEach(e => {
        if (FilterKey !== null && FilterKey !== undefined && FilterKey !== "") {
          if (
            DistinctArray.filter(DE => DE[FilterKey] === e[FilterKey]).length <=
            0
          )
            DistinctArray.push(e);
        } else {
          if (DistinctArray.indexOf(e) === -1) DistinctArray.push(e);
        }
      });
    } catch (error) {
      DistinctArray = [];
    }
    return DistinctArray;
  }

Demo 2

Answer 2

Or the lodash way:

lodash.uniq(this.data.map(x => x.acctId));

Answer 3

you can used rxjs library to

import { of } from 'rxjs';
import { distinct } from 'rxjs/operators';

interface Person {
age: number,
name: string
}

of<Person>(
    { age: 4, name: 'Foo'},
    { age: 7, name: 'Bar'},
    { age: 5, name: 'Foo'},
).pipe(
    distinct((p: Person) => p.name),
)
.subscribe(x => console.log(x));