CODEWITHSUNDEEP
javascript
Stackunderflow
Stackunderflow

Reputation: 61

Listing values in list of dictionaries

var dicList = [{
  student_id: 334,
  full_name: "student B",
  score: 9,
  class_id: 222
}, {
  student_id: 333,
  full_name: "student A",
  score: 7,
  class_id: 222
}]

for (var i = 0; i++; i < dicList.length) {
  for (var key in dicList[i]) {
    if (test.hasOwnProperty(key)) {
      console.log(key, dicList[i][key]);
    }
  }
}

currently returns undefined, I want it to return a list of the values for each attribute in each dictionary

Upvotes: 2

Views: 66

Answers (2)

Maheer Ali
Maheer Ali

Reputation: 36564

You can use flatMap() and Object.entries() and forEach() iterate through result array.

Array.prototype.flatMap = function(f){
  return [].concat(...this.map(f))
}
var dicList = [{student_id: 334,  full_name: "student B",  score: 9,  class_id: 222}, {  student_id: 333,  full_name: "student A",  score: 7,  class_id: 222}]

const res = dicList.flatMap(Object.entries)
res.forEach(([key,value]) => console.log(`key:${key} value:${value}`));

flatMap() doesnot work in all browsers so you use map() and create nested forEach()

var dicList = [{student_id: 334,  full_name: "student B",  score: 9,  class_id: 222}, {  student_id: 333,  full_name: "student A",  score: 7,  class_id: 222}]

const res = dicList.map(Object.entries)
res.forEach(a => a.forEach(([key,value]) => console.log(`key:${key} value:${value}`)));
Array.prototype.flatMap = function(f){
  return [].concat(...this.map(f))
}

You can also create polyfill for flatMap()

if(!Array.prototype.flatMap){
  Array.prototype.flatMap = function(f){
    return [].concat(...this.map(f))
  }
}

Upvotes: 2

Nina Scholz
Nina Scholz

Reputation: 386570

You need to

  • swich the last two parts, condition and final-expression part of the for statement, and

    for ([initialization]; [condition]; [final-expression])
    statement

  • check dicList[1] instead of test.

var dicList = [{ student_id: 334, full_name: "student B", score: 9, class_id: 222 }, { student_id: 333, full_name: "student A", score: 7, class_id: 222 }]

for (var i = 0; i < dicList.length; i++) {     // move i++ to the end
    for (var key in dicList[i]) {
        if (dicList[i].hasOwnProperty(key)) {  // use dicList[i] instead of test
            console.log(key, dicList[i][key]);
        }
    }
}

Upvotes: 1

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