CODEWITHSUNDEEP
javascripttypescript
Jack N
Jack N

Reputation: 175

Group list of objects by JSON key

I am trying to reformat my list of objects by grouping a certain key pair in javascript.

Data Format

[{
    "sccode": "sccode1",
    "val": "1ADA"
}, {
    "sccode": "sccode2",
    "val": "1ADB"
}, {
    "sccode": "sccode1",
    "val": "1ADC"
}]

Expected Result

[{
        "scCode": "sccode1",
        "valCodes": ["1ADA", "1ADC"]
    }, 
{
        "scCode": "sccode2",
        "valCodes": ["1ADB"]
    }

]

I believe I could loop through the array and match my keys, but is there a quick way to reformat this without having to explicitly loop through? I've tried using a reduce function below, but it gives undefined errors with find, which i think has something to do with my formatting.

Tried (?) Code

 const resp = data.reduce((acc, ele) => {
          const ant = acc.find(x => x.sccode === ele.sccode);
        }, []);

Upvotes: 1

Views: 74

Answers (4)

TheGr8_Nik
TheGr8_Nik

Reputation: 3200

Try the following, I use a map to store a partial state to improve performances preventing to search sccode in an array for every initial object.

let partial = [{
  "sccode": "sccode1",
  "val": "1ADA"
}, {
  "sccode": "sccode2",
  "val": "1ADB"
}, {
  "sccode": "sccode1",
  "val": "1ADC"
}].reduce((map, obj) => {
  if (!map[obj.sccode]) {
    map[obj.sccode] = [obj.val];
  } else {
    map[obj.sccode].push(obj.val);
  }
  return map;
}, {})

Object.keys(partial).map(sccode => ({
  sccode, valCodes: partial[sccode]
}));

Upvotes: 1

Leonardo Oliveira
Leonardo Oliveira

Reputation: 1

Check this code: 

    array.reduce(function(res, value){
        if(!res[value.sccode]) {
            res[value.sccode] = value; 
            res[value.sccode]['valCodes'] = []
            result.push(res[value.sccode]);
        }
        res[value.sccode]['valCodes'].push(value.val); 
        return res; 
    } ,{});

I tested here and it works fine!

Upvotes: 0

Nonik
Nonik

Reputation: 655

try loaddash/groupby

let groupByResult = groupBy(data, function (n) {
          return n.sccode
        });

Upvotes: 0

Yevhen Horbunkov
Yevhen Horbunkov

Reputation: 15530

Would this do?

const src = [{"sccode":"sccode1","val":"1ADA"},{"sccode":"sccode2","val":"1ADB"},{"sccode":"sccode1","val":"1ADC"}],

    result = src.reduce((r,{sccode,val}) => {
      const match = r.find(({scCode}) => scCode == sccode)
      match ?
      match.valCodes.push(val) :
      r.push({scCode:sccode, valCodes: [val]})
      return r
    }, [])
    
console.log(result)
.as-console-wrapper{min-height:100%;}

Upvotes: 2

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