Merging arrays of objects with a common key but different structure-CodePudding

I'm working this problem in Typescript and I've been struggling with for a little bit of time now, and was hoping that the kind users of StackOverflow could help :)

Given the two array structures:

var localUsers = [{
    firstName: "Joe", 
    lastName: "Bloggs", 
    id: "44c021ab-be92-409b-99ad-4c3fe61d894a"
}, {
    firstName: "Pete", 
    lastName: "Doe", 
    id: "017b4dab-d58b-475e-ab31-6363d9de25c0"
}, {
    firstName: "Andy", 
    lastName: "NotRemote", 
    id: "2233e4cb-d324-463d-9a42-24b1b4cd3e11"
}]

//Above array is used for a database lookup

var remoteUsers = [{ 
    id: "44c021ab-be92-409b-99ad-4c3fe61d894a",
    timestamp: "2017-07-01T12:00:00.000"
}, {
    id: "017b4dab-d58b-475e-ab31-6363d9de25c0",
    timestamp: "2017-07-01T13:30:00.000"
}]

I want to merge these arrays via the id key, all keys in remoteUsers will have a match in localUsers, but the opposite is not always true. This should give an output similar to:

var allUsers = [{
    firstName: "Joe", 
    lastName: "Bloggs", 
    id: "44c021ab-be92-409b-99ad-4c3fe61d894a",
    timestamp: "2017-07-01T12:00:00.000"
}, {
    firstName: "Pete", 
    lastName: "Doe", 
    id: "017b4dab-d58b-475e-ab31-6363d9de25c0",
    timestamp: "2017-07-01T13:30:00.000"
}, {
    firstName: "Andy", 
    lastName: "NotRemote", 
    id: "2233e4cb-d324-463d-9a42-24b1b4cd3e11",
    timestamp: null
}]

I don't have access to libraries such as underscore or lodash for the time being.

Thank you for taking the time to help!

CodePudding user response：

Merge them with map function

let localUsers = [{ firstName: "Joe", lastName: "Bloggs", id: "44c021ab-be92-409b-99ad-4c3fe61d894a" }, { firstName: "Pete", lastName: "Doe", id: "017b4dab-d58b-475e-ab31-6363d9de25c0" }, { firstName: "Andy", lastName: "NotRemote", id: "2233e4cb-d324-463d-9a42-24b1b4cd3e11" }]
let remoteUsers = [{ id: "44c021ab-be92-409b-99ad-4c3fe61d894a", timestamp: "2017-07-01T12:00:00.000" }, { id: "017b4dab-d58b-475e-ab31-6363d9de25c0", timestamp: "2017-07-01T13:30:00.000" }]

localUsers = localUsers.map(itm => Object.assign(itm, {timestamp: remoteUsers.find(ru => ru.id == itm.id)?.timestamp}))
console.log(localUsers)

CodePudding user response：

This is something that I quickly came up with not optimized but does the job. Hope this helps. Answer from Saeed looks better.

function containsID(id, list) {
    var i;
    for (i = 0; i < list.length; i  ) {
        if (list[i].id === id) {
            return list[i];
        }
    }

    return false;
}

function mergeUsers(local, remote){
    var allUsers = []
    for (const user of local) {
        var isContainsID = containsID(user.id, remote);
        
        allUsers.push({
            firstName: user.firstName,
            lastName: user.lastName,
            id: user.id,
            timestamp: isContainsID.id || null
        });
    }
    return allUsers;
}

CodePudding user response：

You can do:

const localUsers = [{ firstName: "Joe", lastName: "Bloggs", id: "44c021ab-be92-409b-99ad-4c3fe61d894a" }, { firstName: "Pete", lastName: "Doe", id: "017b4dab-d58b-475e-ab31-6363d9de25c0" }, { firstName: "Andy", lastName: "NotRemote", id: "2233e4cb-d324-463d-9a42-24b1b4cd3e11" }]
const remoteUsers = [{ id: "44c021ab-be92-409b-99ad-4c3fe61d894a", timestamp: "2017-07-01T12:00:00.000" }, { id: "017b4dab-d58b-475e-ab31-6363d9de25c0", timestamp: "2017-07-01T13:30:00.000" }]


const removeUsersObject = remoteUsers.reduce((a, c) => (a[c.id]= c, a), {})
const result = localUsers.map(u => ({ 
  ...u,
  timestamp: null,
  ...removeUsersObject[u.id],
}))

console.log(result)