javascript object filter based on multiple conditions

Question

I have the following object and I want to filter it based on some properties and output only some parts of it.

{
    "email" : "[email protected]",
    "name" : " John Doe",
    "groups" : [
        {
            "name" : "group1",
            "country": "US",
            "contacts" : [
                { "localId" : "c1", "address" : "some address 1" },
                { "localId" : "c2", "address" : "some address 2" },
                { "localId" : "c3", "address" : "some address 3" }
            ]
        },
        {
            "name" : "group2",
            "country": "Canada",
            "contacts" : [
                { "localId" : "c1", "address" : "some address 1" },
                { "localId" : "c3", "address" : "some address 3" }
            ]
        }
    ]
}

the result should look like:

{
    "email" : "[email protected]",
    "name" : " John Doe",
    "groups" : [
        {
            "name" : "group1",
            "country": "US",
            "contacts" : [
                {
                  "localId" : "c3", 
                  "address" : "some address 3" 
                }
            ]
        }
    ]
}

So my conditions are:

groups.name="group1"
groups.contacts.localId="c3"

how can I achieve it using some ecma6 js function? with the least memory load? I am in nodejs env >=8.9.0.

update:

here is my failing attempt:

const conditions = {"groups.name": "group1", "groups.contacts.localId": "c3"};
let res = mylist.map((i)=>{
  return {
      email: i.email,
      name: i.name,
      groupsName: conditions.groups.name
  }

})

Please show what you have tried. Stackoverflow isn't a free code writing service. The objective is to help you fix your code — charlietfl
– charlietfl, Commented Jan 7, 2018 at 1:36
@charlietfl please see the updated question wit my failing attempt. — Bonnard
– Bonnard, Commented Jan 7, 2018 at 1:43

Mark · Accepted Answer · 2018-01-07 02:01:47Z

1

You can do this fairly succinctly with filter(). If you filter on group name first you won't waste time filtering the contacts:

let obj = {
  "email": "[email protected]",
  "name": " John Doe",
  "groups": [{
      "name": "group1",
      "country": "US",
      "contacts": [{
          "localId": "c1",
          "address": "some address 1"
        },
        {
          "localId": "c2",
          "address": "some address 2"
        },
        {
          "localId": "c3",
          "address": "some address 3"
        }
      ]
    },
    {
      "name": "group2",
      "country": "Canada",
      "contacts": [{
          "localId": "c1",
          "address": "some address 1"
        },
        {
          "localId": "c3",
          "address": "some address 3"
        }
      ]
    }
  ]
}

let newObj = {
  "email": obj.email,
  "name": obj.name,
  "groups": obj.groups.filter(item => item.name == "group1").map(g => (g.contacts = g.contacts.filter(c => c.localId == "c3"), g))
}
console.log(newObj)

answered Jan 7, 2018 at 2:01

Mark

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2 Comments

Bonnard Over a year ago

what is the comma g at the end of the filter/map line?

Mark Over a year ago

Hi @Bonnard, that's the comma operator. It makes g the return value of the map. More here: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

mdatsev · Accepted Answer · 2018-01-07 01:56:53Z

0

You can use filter and map. If obj is your initial object then you can do:

obj.groups = obj.groups.filter((g)=>g.name==="group1")
for(int i = 0; i < obj.groups.length;i++)
{
    obj.groups[i].contacts = obj.groups[i].contacts.filter((c)=>c.localId==="c3"))
}

edited Jan 7, 2018 at 1:56

answered Jan 7, 2018 at 1:44

mdatsev

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