How to merge two arrays of objects, filtering out matching ID's and merging objects with matchi-CodePudding

I need to combine two arrays of objects:

const local: [
    {id: 1, balance: 2200, ref: 'A'},
    {id: 2, balance: 2100, ref: 'C'}
]
const remote: [
    {id: 1, balance: 3300, ref: 'B'},
]

I need to merge these arrays, such any two objects with the same id are merged - keeping the same ID, keeping the balance from remote and combining their ref values, so the ideal output of this example would be:

  [
       { id: 1, balance: 3300, text: 'A / B' },
       { id: 2, balance: 2100, text: 'C' }
  ]

How would I do this? Ive tried the following:

function mergeFunc(remoteArray, localArray) {
    const newArray = [];
    //loop over one of the arrays
    for (const localObj of localArray) {
        //for each iteration, search for object with matching id in other array
        if(remoteArray.some(remoteObj => remoteObj.id === localObj.id)){
            //if found matching id, fetch this other object
            const id:matchingRemoteObj = remoteArray.find(item => item.id === localObj.id);
            //create new, merged, object
            const newObj = {id:matchingRemoteObj.id, balance: id:matchingRemoteObj.balance, text:`${localObj.text} / ${id:matchingRemoteObj.text}`}
            //push new value to array
            newArray.push(newObj);
        }
    }
    return newArray;
}

The issue is, this solution gives me an array of merged objects that had matching ID's. I need an array with all objects, only merging the ones with matching id's...

CodePudding user response：

The reason is below code,you just push match records,which cause this issue

if(remoteArray.some(remoteObj => remoteObj.id === localObj.id))

Below is a reference for you by using Array.map() and Array.find()

const local = [
    {id: 1, balance: 2200, ref: 'A'},
    {id: 2, balance: 2100, ref: 'C'}
]
const remote = [
    {id: 1, balance: 3300, ref: 'B'},
]

let result = local.map(e =>{
  let r = remote.find(i => i.id === e.id)
  let ref = r?.ref
  if(ref){
    e.balance = r.balance
    e.ref  = ' / '   ref
   }
  return e
})
console.log(result)

Update: If you want to make your original code works,you need to add else block if there is no match

const local = [
    {id: 1, balance: 2200, ref: 'A'},
    {id: 2, balance: 2100, ref: 'C'}
]
const remote = [
    {id: 1, balance: 3300, ref: 'B'},
]


function mergeFunc(remoteArray, localArray) {
    const newArray = [];
    //loop over one of the arrays
    for (const localObj of localArray) {
        //for each time, search for object with matching id in other array
        if(remoteArray.some(remoteObj => remoteObj.id === localObj.id)){
            //if found matching id, fetch this other object
            const matchingRemoteObj = remoteArray.find(item => item.id === localObj.id);
            //create new, merged, object
            const newObj = {id:matchingRemoteObj.id, balance: matchingRemoteObj.balance, text:`${localObj.ref} / ${matchingRemoteObj.ref}`}
            //push new value to array
            newArray.push(newObj);
        }else{
          // this will add not match record into result array
          newArray.push(localObj) 
        }
    }
    return newArray;
}

let result = mergeFunc(remote,local)
console.log(result)

CodePudding user response：

You can make use of array.map and array.find method,

To replace the balance of the match with the remote array you can use,

obj.balance = o.balance

To merge the ref string of matching id, you can use,

obj.ref = `${obj.ref} / ${o.ref}`

Working Snippet:

const local = [
    { id: 1, balance: 2200, ref: "A" },
    { id: 2, balance: 2100, ref: "C" },
  ];
  const remote = [{ id: 1, balance: 3300, ref: "B" }];

  const result = local.map((obj) => {
    remote.find((o) => {
      if (o.id === obj.id) {
        obj.balance = o.balance;
        obj.ref = `${obj.ref} / ${o.ref}`;
      }
    });
    return obj;
  });

  console.log(result);