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

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"]
   }

   ]

CodePudding user response：

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)

CodePudding user response：

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)