Transform keys to values, values to keys in json object using typescript

Question

Im trying to swap key to values, values to key, but could not find right solution using javascript/typescript.

  course =  
  [ 
   { 
     "name" : "John",
     "course" : ["Java", "Python"]
   },
   { 
     "name" : "Michel",
     "course" : ["Java", "Python", "Ruby"]
   }
   ]

I want the result json is like below:

  result = [
   {
     "course" : "Java",
     "name" : ["John", "Michel"]

   }, 
   {
     "course" : "Python",
     "name" : ["John", "Michel"]
   },
   {
     "course" : "Ruby",
     "name" : ["Michel"]
   }

   ]

cmgchess · Accepted Answer · 2022-07-27 05:42:10Z

1

Here is a JS solution. I'm grouping using reduce to get this intermediate object

{
  Java: {
    course: "Java",
    name: ["John", "Michel"]
  },
  Python: {
    course: "Python",
    name: ["John", "Michel"]
  },
  Ruby: {
    course: "Ruby",
    name: ["Michel"]
  }
}

Then I'm calling Object.values on this intermediate object to the values array as you needed

const course =  [    {      "name" : "John",     "course" : ["Java", "Python"]   },   {      "name" : "Michel",     "course" : ["Java", "Python", "Ruby"]   }   ]

const result = Object.values(course.reduce((acc,{name,course}) => {
  course.forEach(c => {
    acc[c]??={course:c,name:[]}
    acc[c].name.push(name)
  })
  return acc
},{}))

console.log(result)

answered Jul 27, 2022 at 5:42

cmgchess

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Comments

kennarddh · Accepted Answer · 2022-07-27 05:35:46Z

0

const course = [{
    name: 'John',
    course: ['Java', 'Python'],
  },
  {
    name: 'Michel',
    course: ['Java', 'Python', 'Ruby'],
  },
]

const temp = course.reduce((acc, value) => {
  value.course.forEach(item => {
    if (!acc[item]) {
      acc[item] = []
    }

    acc[item].push(value.name)
  })

  return acc
}, {})

const result = Object.entries(temp).reduce((acc, [course, name]) => {
  acc.push({
    course,
    name,
  })

  return acc
}, [])

console.log(result)

answered Jul 27, 2022 at 5:35

kennarddh

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