double nested array of object es6 filter

Question

I want to filter out a nested array of objects but stuck at the filter part.

How to remove one of the mark?

this.state = {
  data: [
    {
      id: 1,
      name: "Main",
      subs: [
        {
          id: "jay",
          name: "Jay",
          mark: [
            {
              id: "5a5d84b94a074c49ef2d4553",
              name: 100
            },
            {
              id: "5a5d84b94a074119ef2d4553",
              name: 70
            }
          ]
        }
      ]
    }
  ]
};

https://codesandbox.io/s/p39momxzp7

I try to use es6 as it's more readable.

expected output

data: [
  {
    id: 1,
    name: "Main",
    subs: [
      {
        id: "jay",
        name: "Jay",
        mark: [
          {
            id: "5a5d84b94a074119ef2d4553",
            name: 70
          }
        ]
      }
    ]
  }
]

Answer 1

Since there are multiple nested arrays in your data structure, you need to use forEach those many times

data.forEach( s =>  //iterate data
      s.subs.forEach( t => //iterate subs
         ( t.mark = t.mark.slice( 1, 2 ) ) ) ); //slice the second value out

Demo

 var data = [{ id: 1, name: "Main", subs: [{ id: "jay", name: "Jay", mark: [{ id: "5a5d84b94a074c49ef2d4553", name: 100 }, { id: "5a5d84b94a074119ef2d4553", name: 70 } ] }] }]; data.forEach(s => s.subs.forEach(t => (t.mark = t.mark.slice(1,2)))); console.log(JSON.stringify(data, 0, 4)) 

In case the last value should be picked ?

data.forEach( s =>  //iterate data
      s.subs.forEach( t => //iterate subs
         ( t.mark = t.mark.slice( -1 ) ) ) ); //slice the last value out

Answer 2

If you are trying to filter a relevant mark by a given id ,
you can combine Array#map and Array#filter to achieve it:

Note that i'm also using the Object Rest/Spread Properties proposal (stage 4)

Running example

 const state = { data: [{ id: 1, name: "Main", subs: [{ id: "jay", name: "Jay", mark: [{ id: "5a5d84b94a074c49ef2d4553", name: 100 }, { id: "5a5d84b94a074119ef2d4553", name: 70 }] }] }] }; const mark_id = '5a5d84b94a074119ef2d4553'; const nextState = { ...state, data: state.data.map(obj => { const filteredSubs = obj.subs.map(sub => { const markById = sub.mark.filter(m => m.id === mark_id); return { ...sub, mark: markById } }); return { ...obj, subs: filteredSubs } }) }; console.log(nextState); 

Answer 3

You can even use lodash which contains many methods that can be handled easily.

Check if this is what you are looking for. (there is a good scope to refactor it but before that would like to understand if thats what you are looking for)

Below is the code that has been used there.

let inputId = "5a5d84b94a074c49ef2d4553";
    let filteredData =_.each(_.cloneDeep(data), function(value, key1) {
      _.each(value.subs, function(valueSubs, key2) {
        var finalSubMark = _.find(valueSubs.mark, function(eachMark) {
          return eachMark.id == inputId;
        });
        _.set(valueSubs, "mark", finalSubMark);
      });
    });

https://codesandbox.io/s/v065w05rly