Filter data from array Angular 2

Question

I have 2 arrays and I want to filter data based on column value. I am using below code but It is not working.

const result = data.map(data1 => {
            return Object.assign({}, data1, this.data2.filter(data2 => data2.Id !== data1.Id)[0]);
        });

Data 1 :

[
  {
    "id": 2,
    "name": "data 2",
  },
  {
    "id": 3,
    "name": "data 3",
  }
]

Data 2 :

[
  {
    "id": 2,
    "name": "data 2"
  },
  {
    "id": 3,
    "name": "data 3"
  },
  {
    "id": 4,
    "name": "data 4"
  }
]

It should return below output.

[
{
    "id": 4,
    "name": "data 4"
}
]

How do I solve this ?

Can you provide a sample of what are your input arrays are and what output you expect? — Eeks33, May 12 '17 at 16:09
So, you want to keep all the objects in data2 that don't exist in data1 (and use their ID to know if they exist or not in data1), is that right? — JB Nizet, May 12 '17 at 16:25
Possible duplicate of [JavaScript array difference](http://stackoverflow.com/questions/1187518/javascript-array-difference) — developer033, May 12 '17 at 16:26
So you don't need any Object.assign. All you need is data2.filter(element => !elementExistsInData1WithId(element.id)). I'll leave the implementation of elementExistsInData1WithId as an exercise. Array.some() is useful. — JB Nizet, May 12 '17 at 16:27
Check this for ES¨: https://stackoverflow.com/a/49639411/4654957 — Diego Venâncio, Apr 03 '18 at 22:48

score 6 · Accepted Answer · edited May 23 '17 at 12:26

6

What you're looking for is a difference of 2 arrays of objects, see: Difference between two array of objects in JavaScript

You can also go by pure ids like this:

let ids = data1.map(item => item.id);
let filteredData = data2.filter(item => ids.indexOf(item.id) === -1);

edited May 23 '17 at 12:26

Community

answered May 12 '17 at 16:28

Eeks33

1 Answers1