How to create a new object derived from three objects with JavaScript?

amal m reji 0
Viewed 47

Hello guys I have a doubt regarding JavaScript Objects!. Thanks in advance for any future answers. I will explain my situation here. 1)I have 3 objects named courses,admission_details,attendance. 2)I need to create another object from this 3 objects.

const COURSES=[
    {
        PROGRAM: "BTech",
        COURSE: 'PHYSICS',
        FEE:200
    },
    {
        PROGRAM: "BTech",
        COURSE: 'CHEMISTRY',
        FEE:200
    },
    {
        PROGRAM: "BTech",
        COURSE: 'BIOLOGY',
        FEE:200
    }
]

const ADMISSION_DETAILS=[
    {
     NAME:'AJU', REGISTER_NUMBER:'JAJEGJAFD512315',
     EMAIL:'xxxxxasdf@gmail.com',
     PHONE:'974654645454'
    }
]

const ATTENDANCE = [
    {
        NAME: 'AJU',
        REGISTER_NUMBER: 'JAJEGJAFD512315',
        ATTENDANCE:{
            PHYSICS:75,
            CHEMISTRY:86,
            BIOLOGY:40
        }
    }
]
i want to create another new object from this 3 array of objects,but i am stuck while doing this. 
const desired_output=[
    {
        NAME:'AJU',
        REGISTER_NUMBER:'JAJEGJAFD512315',
        EMAIL:'xxxxxasdf@gmail.com',
        PHONE:'974654645454',
        PROGRAM: "BTech",
        COURSE:"PHYSICS",
        ATTENDANCE:75,
        FEE:200,
    },
    {
        NAME:'AJU',
        REGISTER_NUMBER:'JAJEGJAFD512315',
        EMAIL:'xxxxxasdf@gmail.com',
        PHONE:'974654645454',
        PROGRAM: "BTech",
        COURSE:"CHEMISTRY",
        ATTENDANCE:86,
        FEE:200
    },
     {
        NAME:'AJU',
        REGISTER_NUMBER:'JAJEGJAFD512315',
        EMAIL:'xxxxxasdf@gmail.com',
        PHONE:'974654645454',
        PROGRAM: "BTech",
        COURSE:"BIOLOGY",
        ATTENDANCE:40,
        FEE:200
    }
]
This was the desired output.Please anyone help me to achieve this.

javascript-objects reactjs node.js javascript angular
2 Answers

How about this? Loop over ADMISSION_DETAILS, which then find the person, loop over the persons courses, fit everything into an object.

const COURSES=[
    {
        PROGRAM: "BTech",
        COURSE: 'PHYSICS',
        FEE:200
    },
    {
        PROGRAM: "BTech",
        COURSE: 'CHEMISTRY',
        FEE:200
    },
    {
        PROGRAM: "BTech",
        COURSE: 'BIOLOGY',
        FEE:200
    }
]

const ADMISSION_DETAILS=[
    {
     NAME:'AJU', REGISTER_NUMBER:'JAJEGJAFD512315',
     EMAIL:'xxxxxasdf@gmail.com',
     PHONE:'974654645454'
    }
]

const ATTENDANCE = [
    {
        NAME: 'AJU',
        REGISTER_NUMBER: 'JAJEGJAFD512315',
        ATTENDANCE:{
            PHYSICS:75,
            CHEMISTRY:86,
            BIOLOGY:40
        }
    }
]

const desired_output = ADMISSION_DETAILS.reduce((acc, ad) => { 
  const at = ATTENDANCE.find(p => p.REGISTER_NUMBER ===       ad.REGISTER_NUMBER)
 return [...acc,...Object.keys(at.ATTENDANCE).map(ck => {
  const course = COURSES.find(c => c.COURSE === ck)
  return {
  ...ad,
  ...course,
  ATTENDANCE: at.ATTENDANCE[ck]
  }
})]
}, [])
console.log(desired_output)

Disco0

Basically you need to employ a combination of iterators object/array manipulators. After setting up the outside iterator to work through the array of users, I used each user's ATTENDANCE object as the iterator - by converting it into an array of keys. Along the way, I find the matching data in other variables using Array.find(), then combine objects together using the ... spread operator which allows us to create a copy (not a reference).

const COURSES = [{
    PROGRAM: "BTech",
    COURSE: 'PHYSICS',
    FEE: 200
  },
  {
    PROGRAM: "BTech",
    COURSE: 'CHEMISTRY',
    FEE: 200
  },
  {
    PROGRAM: "BTech",
    COURSE: 'BIOLOGY',
    FEE: 200
  }
]

const ADMISSION_DETAILS = [{
  NAME: 'AJU',
  REGISTER_NUMBER: 'JAJEGJAFD512315',
  EMAIL: 'xxxxxasdf@gmail.com',
  PHONE: '974654645454'
}]

const ATTENDANCE = [{
  NAME: 'AJU',
  REGISTER_NUMBER: 'JAJEGJAFD512315',
  ATTENDANCE: {
    PHYSICS: 75,
    CHEMISTRY: 86,
    BIOLOGY: 40
  }
}]

let combined = [];

ATTENDANCE.forEach(a => {
  let courses = a.ATTENDANCE;
  let keys = Object.keys(courses);
  keys.forEach(key => {
    let obj = { ...a};
    delete obj.ATTENDANCE;
    // get the actual attendance
    obj.ATTENDANCE = courses[key]
    // get user details
    let user = ADMISSION_DETAILS.find(f => f.REGISTER_NUMBER = a.REGISTER_NUMBER) || {}
    let course = COURSES.find(f => f.COURSE = key) || {}
    obj = { ...obj,
      ...user,
      ...course
    }
    combined.push(obj)
  })
})

console.log(combined)

/*
 NAME:'AJU',
        REGISTER_NUMBER:'JAJEGJAFD512315',
        EMAIL:'xxxxxasdf@gmail.com',
        PHONE:'974654645454',
        PROGRAM: "BTech",
        COURSE:"BIOLOGY",
        ATTENDANCE:40,
        FEE:200
        */

Kinglish0
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