How to loop over json data and merge rows with the same state id?

Question

I have .json file of us-senat that has two senators for each state. I would like to loop over this json file and create new JS object that should have state id as a key and then set two properties for each key name1 and name2. Here is example of how data looks in original file:

var senatorData = [{
    state_code: "AK",
    name: "Daniel Sullivan"
  },
  {
    state_code: "AK",
    name: "Lisa Murkowski"
  },
  {
    state_code: "WY",
    name: "Michael Enzi"
  },
  {
    state_code: "WY",
    name: "John Barrasso"
  }
];

$(document).ready(function(){
  loadData();
});

function loadData() {
  if (senatorData) {
    for (var key in senatorData) {
      console.log(senatorData[key]);
    }
  }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

In example I just showed the original data, here is what I would like to have:

var senatorDataNew = [
    "AK" = {
         name1: "Daniel Sullivan",
         name2: "Lisa Murkowski"
     },
     "WY" = {
         name1: "Michael Enzi",
         name2: "John Barrasso"
     }
];

While looping I would set new key and set the name1 property with value, if key already exists I need to keep name1 and set second property name2 with new value. I'm wondering if this is possible and what is the easiest way to achieve that?

@Taplar That is an option as well. If you can provide example that will help. Thank you. — espresso_coffee, Dec 03 '18 at 18:49

score 2 · Answer 1 · answered Dec 03 '18 at 18:53

Are you looking for something like this?

senatorDataNew = {};    
senatorData.forEach(senator => {
    if (! senatorDataNew[senator.state_code]) {
        senatorDataNew[senator.state_code] = {names: []};
    }

    senatorDataNew[senator.state_code].names.push(senator.name)
});

score 2 · Accepted Answer · answered Dec 03 '18 at 18:56

If there are only 2 senators, you can use reduce and set the name1 or name2 property in the object next to the key based on whether or not a key is already present in the accumulator:

function loadData() {
  if (senatorData) {
    return senatorData.reduce((a, {state_code, name}) => {
      if (state_code in a) a[state_code].name2 = name;
      else a[state_code] = {name1: name};
      return a;
    }, {});
  }
}

var senatorData = [{
    state_code: "AK",
    name: "Daniel Sullivan"
  },
  {
    state_code: "AK",
    name: "Lisa Murkowski"
  },
  {
    state_code: "WY",
    name: "Michael Enzi"
  },
  {
    state_code: "WY",
    name: "John Barrasso"
  }
];

$(document).ready(function(){
  console.log(loadData());
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

score 1 · Answer 3 · answered Dec 03 '18 at 18:55

var senatorData = [{
    state_code: "AK",
    name: "Daniel Sullivan"
  },
  {
    state_code: "AK",
    name: "Lisa Murkowski"
  },
  {
    state_code: "WY",
    name: "Michael Enzi"
  },
  {
    state_code: "WY",
    name: "John Barrasso"
  }
];

//convert the object into an object of key (state) and value (names)
senatorData = senatorData.reduce(function(results, senator){
  if (!results[senator.state_code]) results[senator.state_code] = [];
  
  results[ senator.state_code ].push(senator.name);
  return results;
}, {});

console.log(senatorData);

//convert the object into an array of objects
senatorData = Object.keys(senatorData).map(function(state){
  return { state_code: state, names: senatorData[state] };
});

console.log(senatorData);

How to loop over json data and merge rows with the same state id?

3 Answers3