Reduce object, grouping by a key

Question

I have the following which is almost where I need to be

var baseData= [{
    "id": 1,
    "username": "JJ",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "J",
    "surname": "J",
    "band": "Band 7",
    "role": "Developer",
    "competency": "Kicks",
    "employeeNumber": null,
    "name": "Sedation"
}, {
    "id": 1,
    "username": "JJ",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "J",
    "surname": "J",
    "band": "Band 7",
    "role": "Developer",
    "competency": "Kicks",
    "employeeNumber": null,
    "name": "Safeguarding Level 3"
}, {
    "id": 1,
    "username": "JJ",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "J",
    "surname": "J",
    "band": "Band 7",
    "role": "Developer",
    "competency": "Kicks",
    "employeeNumber": null,
    "name": "Safeguarding Level 2"
}, {
    "id": 276,
    "username": "IH",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "I",
    "surname": "Hashmi",
    "band": "Band 8",
    "role": "Chap",
    "competency": "Pie",
    "employeeNumber": null,
    "name": "Safeguarding Level 3"
}, {
    "id": 276,
    "username": "IH",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "I",
    "surname": "Hashmi",
    "band": "Band 8",
    "role": "Chap",
    "competency": "Pie",
    "employeeNumber": null,
    "name": "Safeguarding Level 2"
}, {
    "id": 276,
    "username": "IH",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "I",
    "surname": "Hashmi",
    "band": "Band 8",
    "role": "Chap",
    "competency": "Pie",
    "employeeNumber": null,
    "name": "Major Incident"
}, {
    "id": 277,
    "username": "LC",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "L",
    "surname": "C",
    "band": "Band 9",
    "role": "Lady",
    "competency": "Pizza",
    "employeeNumber": null,
    "name": "WMH ED Nursing"
}, {
    "id": 277,
    "username": "LC",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "L",
    "surname": "C",
    "band": "Band 9",
    "role": "Lady",
    "competency": "Pizza",
    "employeeNumber": null,
    "name": "Sedation"
}, {
    "id": 277,
    "username": "LC",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "L",
    "surname": "C",
    "band": "Band 9",
    "role": "Lady",
    "competency": "Pizza",
    "employeeNumber": null,
    "name": "Safeguarding Level 3"
}, {
    "id": 281,
    "username": "MJ",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "M",
    "surname": "J",
    "band": "Band 9",
    "role": "Solutions Developer Manager",
    "competency": "Ninja",
    "employeeNumber": "23546329",
    "name": "Digital Team"
}, {
    "id": 283,
    "username": "CG",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "C",
    "surname": "G",
    "band": "5",
    "role": "Senior Solutions Developer",
    "competency": "LOL",
    "employeeNumber": "23546205",
    "name": "WMH ED Medics"
}, {
    "id": 283,
    "username": "CG",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "C",
    "surname": "G",
    "band": "5",
    "role": "Senior Solutions Developer",
    "competency": "LOL",
    "employeeNumber": "23546205",
    "name": "WMH ED Nursing"
}, {
    "id": 283,
    "username": "CG",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "C",
    "surname": "G",
    "band": "5",
    "role": "Senior Solutions Developer",
    "competency": "LOL",
    "employeeNumber": "23546205",
    "name": "Sedation"
}, {
    "id": 283,
    "username": "CG",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "C",
    "surname": "G",
    "band": "5",
    "role": "Senior Solutions Developer",
    "competency": "LOL",
    "employeeNumber": "23546205",
    "name": "Safeguarding Level 3"
}, {
    "id": 283,
    "username": "CG",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "C",
    "surname": "G",
    "band": "5",
    "role": "Senior Solutions Developer",
    "competency": "LOL",
    "employeeNumber": "23546205",
    "name": "Safeguarding Level 2"
}, {
    "id": 283,
    "username": "CG",
    "lastLoggedIn": null,
    "archive": false,
    "forename": "C",
    "surname": "G",
    "band": "5",
    "role": "Senior Solutions Developer",
    "competency": "LOL",
    "employeeNumber": "23546205",
    "name": "Major Incident"
}, {
    "id": 284,
    "username": "Bob",
    "lastLoggedIn": null,
    "archive": true,
    "forename": "Bob",
    "surname": "Bob",
    "band": "Bob",
    "role": "Bob",
    "competency": "Bob",
    "employeeNumber": "XXX",
    "name": "WMH ED Medics"
}, {
    "id": 284,
    "username": "Bob",
    "lastLoggedIn": null,
    "archive": true,
    "forename": "Bob",
    "surname": "Bob",
    "band": "Bob",
    "role": "Bob",
    "competency": "Bob",
    "employeeNumber": "XXX",
    "name": "WMH ED Nursing"
}, {
    "id": 284,
    "username": "Bob",
    "lastLoggedIn": null,
    "archive": true,
    "forename": "Bob",
    "surname": "Bob",
    "band": "Bob",
    "role": "Bob",
    "competency": "Bob",
    "employeeNumber": "XXX",
    "name": "Sedation"
}, {
    "id": 284,
    "username": "Bob",
    "lastLoggedIn": null,
    "archive": true,
    "forename": "Bob",
    "surname": "Bob",
    "band": "Bob",
    "role": "Bob",
    "competency": "Bob",
    "employeeNumber": "XXX",
    "name": "Safeguarding Level 3"
}, {
    "id": 284,
    "username": "Bob",
    "lastLoggedIn": null,
    "archive": true,
    "forename": "Bob",
    "surname": "Bob",
    "band": "Bob",
    "role": "Bob",
    "competency": "Bob",
    "employeeNumber": "XXX",
    "name": "Safeguarding Level 2"
}, {
    "id": 284,
    "username": "Bob",
    "lastLoggedIn": null,
    "archive": true,
    "forename": "Bob",
    "surname": "Bob",
    "band": "Bob",
    "role": "Bob",
    "competency": "Bob",
    "employeeNumber": "XXX",
    "name": "Major Incident"
}];
    
    var newData = [];
    baseData.forEach(function(item, index) {
      if (newData.length === 0) {
        newData.push(item);
        
      } else {
        var dIndex = -1;
        newData.forEach(function(itm, idx) {
          if (item.id === itm.id) dIndex = idx;
        });
        
        if (dIndex !== -1) {
          var oldname = newData[dIndex].name;
          
          if (typeof(oldname).toString() === 'string') {
            newData[dIndex].name = [oldname, item.name];
          }
        } else {
          newData.push(item);
        }
      }
    });
    console.log(newData);

jsFiddle: https://jsfiddle.net/jeqdbn12/

This groups/reduces the object by the key called "name".

However it seems to nest the values for key, so using the array above, for Bob, I get:

{
  archive: true,
  band: "Bob",
  competency: "Bob",
  employeeNumber: "XXX",
  forename: "Bob",
  id: 284,
  lastLoggedIn: null,
  name: [[[[["WMH ED Medics", "WMH ED Nursing"], "Sedation"], "Safeguarding Level 3"], "Safeguarding Level 2"], "Major Incident"],
  role: "Bob",
  surname: "Bob",
  username: "Bob"
}

However, what I need is for the key called "name" to be an array of values or a comma delimited string. Any advice?

So I need something like:

...
name: ["value1","value2"]
...

score 2 · Accepted Answer · answered Sep 08 '21 at 09:22

Use Array.reduce

Logic

Loop through array.
Push the nodes to accumulator
Before pushing verify whether there is a node with same id and username already exist in the accumulator.
If yes, push the name of current node to the name array of that node
If not push the node to accumulator with name as a array with the value of current name as the first element.

const baseData = [{"id":1,"username":"JJ","lastLoggedIn":null,"archive":false,"forename":"J","surname":"J","band":"Band 7","role":"Developer","competency":"Kicks","employeeNumber":null,"name":"Sedation"},{"id":1,"username":"JJ","lastLoggedIn":null,"archive":false,"forename":"J","surname":"J","band":"Band 7","role":"Developer","competency":"Kicks","employeeNumber":null,"name":"Safeguarding Level 3"},{"id":1,"username":"JJ","lastLoggedIn":null,"archive":false,"forename":"J","surname":"J","band":"Band 7","role":"Developer","competency":"Kicks","employeeNumber":null,"name":"Safeguarding Level 2"},{"id":276,"username":"IH","lastLoggedIn":null,"archive":false,"forename":"I","surname":"Hashmi","band":"Band 8","role":"Chap","competency":"Pie","employeeNumber":null,"name":"Safeguarding Level 3"},{"id":276,"username":"IH","lastLoggedIn":null,"archive":false,"forename":"I","surname":"Hashmi","band":"Band 8","role":"Chap","competency":"Pie","employeeNumber":null,"name":"Safeguarding Level 2"},{"id":276,"username":"IH","lastLoggedIn":null,"archive":false,"forename":"I","surname":"Hashmi","band":"Band 8","role":"Chap","competency":"Pie","employeeNumber":null,"name":"Major Incident"},{"id":277,"username":"LC","lastLoggedIn":null,"archive":false,"forename":"L","surname":"C","band":"Band 9","role":"Lady","competency":"Pizza","employeeNumber":null,"name":"WMH ED Nursing"},{"id":277,"username":"LC","lastLoggedIn":null,"archive":false,"forename":"L","surname":"C","band":"Band 9","role":"Lady","competency":"Pizza","employeeNumber":null,"name":"Sedation"},{"id":277,"username":"LC","lastLoggedIn":null,"archive":false,"forename":"L","surname":"C","band":"Band 9","role":"Lady","competency":"Pizza","employeeNumber":null,"name":"Safeguarding Level 3"},{"id":281,"username":"MJ","lastLoggedIn":null,"archive":false,"forename":"M","surname":"J","band":"Band 9","role":"Solutions Developer Manager","competency":"Ninja","employeeNumber":"23546329","name":"Digital Team"},{"id":283,"username":"CG","lastLoggedIn":null,"archive":false,"forename":"C","surname":"G","band":"5","role":"Senior Solutions Developer","competency":"LOL","employeeNumber":"23546205","name":"WMH ED Medics"},{"id":283,"username":"CG","lastLoggedIn":null,"archive":false,"forename":"C","surname":"G","band":"5","role":"Senior Solutions Developer","competency":"LOL","employeeNumber":"23546205","name":"WMH ED Nursing"},{"id":283,"username":"CG","lastLoggedIn":null,"archive":false,"forename":"C","surname":"G","band":"5","role":"Senior Solutions Developer","competency":"LOL","employeeNumber":"23546205","name":"Sedation"},{"id":283,"username":"CG","lastLoggedIn":null,"archive":false,"forename":"C","surname":"G","band":"5","role":"Senior Solutions Developer","competency":"LOL","employeeNumber":"23546205","name":"Safeguarding Level 3"},{"id":283,"username":"CG","lastLoggedIn":null,"archive":false,"forename":"C","surname":"G","band":"5","role":"Senior Solutions Developer","competency":"LOL","employeeNumber":"23546205","name":"Safeguarding Level 2"},{"id":283,"username":"CG","lastLoggedIn":null,"archive":false,"forename":"C","surname":"G","band":"5","role":"Senior Solutions Developer","competency":"LOL","employeeNumber":"23546205","name":"Major Incident"},{"id":284,"username":"Bob","lastLoggedIn":null,"archive":true,"forename":"Bob","surname":"Bob","band":"Bob","role":"Bob","competency":"Bob","employeeNumber":"XXX","name":"WMH ED Medics"},{"id":284,"username":"Bob","lastLoggedIn":null,"archive":true,"forename":"Bob","surname":"Bob","band":"Bob","role":"Bob","competency":"Bob","employeeNumber":"XXX","name":"WMH ED Nursing"},{"id":284,"username":"Bob","lastLoggedIn":null,"archive":true,"forename":"Bob","surname":"Bob","band":"Bob","role":"Bob","competency":"Bob","employeeNumber":"XXX","name":"Sedation"},{"id":284,"username":"Bob","lastLoggedIn":null,"archive":true,"forename":"Bob","surname":"Bob","band":"Bob","role":"Bob","competency":"Bob","employeeNumber":"XXX","name":"Safeguarding Level 3"},{"id":284,"username":"Bob","lastLoggedIn":null,"archive":true,"forename":"Bob","surname":"Bob","band":"Bob","role":"Bob","competency":"Bob","employeeNumber":"XXX","name":"Safeguarding Level 2"},{"id":284,"username":"Bob","lastLoggedIn":null,"archive":true,"forename":"Bob","surname":"Bob","band":"Bob","role":"Bob","competency":"Bob","employeeNumber":"XXX","name":"Major Incident"}];
const newData = baseData.reduce((acc, curr) => {
  const node = acc.find((item) => item.id === curr.id && item.username === curr.username);
  if (node) {
    node.name.push(curr.name);
  } else {
    const newNode = { ...curr };
    newNode.name = [curr.name];
    acc.push(newNode)
  }
  return acc;
}, []);
console.log(newData);

In IE/Edge, I get an error on the spread operator i.e. const newNode = { ...curr }. Any advice? — pee2pee, Sep 24 '21 at 11:17
@pee2pee ite issue with IE. Can you check https://stackoverflow.com/questions/64536121/how-to-achieve-the-spread-operator-in-ie-11/64540648 — Nitheesh, Sep 24 '21 at 11:26
Ok, I've sorted the spread operator issue but the arrow function isn't supported so would need a bigger fix — pee2pee, Sep 24 '21 at 11:27

Reduce object, grouping by a key

1 Answers1