Group objects by common property merging the rest of properties as separate objects within array

Question

this is my input, i have an array where name key has value 'foo1' in multiple objects so i want unique object with respect to 'name' key value and other information on a separate array.

var array = [{
    name: "foo1",
    value: "val1",
    status: "1"
  }, {
    name: "foo1",
    value:  "val2",
    status: "0"
  }, {
    name: "foo1",
    value:  "val3",
    status: "1"
  }, {
    name: "foo2",
    value: "val4",
    status: "1"
  }];

and i want on output like below. Below array are unique by name key and other value and status key from all matching object store on new_obj key.

var output = [{
  name: "foo1",
  new_obj: [{
      value:"val1", 
      status: "1"
    }, {
      value:"val2", 
      status: "0"
    }, {
      value:"val3", 
      status: "1"
    }]
  }, {
    name: "foo2",
    new_obj: [{
      value:"val4", 
      status: "1"
    }]  
  }];

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Take a look at this to understand how to ask a good question: https://stackoverflow.com/help/how-to-ask — Kitson, Aug 12 '20 at 13:48
This looks like a duplicate: https://stackoverflow.com/questions/36344976/collect-unique-objects-in-javascript-array — Kitson, Aug 12 '20 at 13:50
Does this answer your question? [Collect unique objects in JavaScript array](https://stackoverflow.com/questions/36344976/collect-unique-objects-in-javascript-array) — Kitson, Aug 12 '20 at 13:50

score 1 · Answer 1 · answered Aug 12 '20 at 13:32

1

var output = array.reduce((acc, value) => {
  if (!acc[value.name]) acc[value.name] = {
    name: value.name,
    new_obj: []
  };
  acc[value.name].new_obj.push({value: value.value, status: value.status});
  return acc;
}, {});

answered Aug 12 '20 at 13:32

siyb

2,837
2
21
18

Yevhen Horbunkov · Accepted Answer · 2020-08-12T14:24:04.190

You may build up (e.g. using Array.prototype.reduce()) the Map, having name values as keys and grouped objects as values, so once you find the name that was already seen (Map.prototype.get() does not return undefined by respective key), you push the rest of properties as a separate object to new_obj, if encountered name was not seen before, you create (with Map.prototype.set()) grouped object for that.

As your Map is ready, you extract its values with Map.prototype.values() into array, using spread syntax:

const arr = [{name:"foo1",value:"val1",status:"1"},{name:"foo1",value:"val2",status:"0"},{name:"foo1",value:"val3",status:"1"},{name:"foo2",value:"val4",status:"1"}],
    
    result = [...arr
      .reduce((acc, {name, ...rest}) => {
          const group = acc.get(name)
          group ? group.new_obj.push(rest) : acc.set(name, {name, "new_obj":[rest]})
          return acc
        }, new Map)
      .values()
    ]
    
console.log(result)

.as-console-wrapper{min-height:100%;}

score 0 · Answer 3 · answered Aug 12 '20 at 13:46

0

You can have a oneliner for this using lodash

_.groupBy(array, 'name')

answered Aug 12 '20 at 13:46

Omkar Kulkarni

1,091
10
22

Group objects by common property merging the rest of properties as separate objects within array

3 Answers3

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