How can I convert these json objects to a proper array?

Question

I have some documents in a Mongodb collection that are of the wrong type, they look like this:

> db.stockData.find({productcode:"EMIM.AS"},{History:1} )

returns

{ "_id" : ObjectId("5cb810770720c53598ea2807")
, "History" : {
  "0" : { "year" : 2018, "value" : 22.659 },
  "1" : { "year" : 2017, "value" : 25.11 }, 
  "2" : { "year" : 2016, "value" : 20.82 }, 
  "3" : { "year" : 2015, "value" : 18.49 } } 
}

The "History" element should be converted to an array, like this:

"History" : [ 
 { "year" : 2018, "value" : 22.659 }
  ,"year" : 2017, "value" : 25.11 },
 ....
 ] }

Is this doable with JavaScript?

addition:

I was not be able to isolate the History object or loop through it. I used this code

db.stockData.find({productcode:"EMIM.AS"},{History:1} , function( err,doc) { console.log(doc[0].History); });
{ "_id" : ObjectId("5cb810770720c53598ea2807"), "History" : { "0" : { "year" : 2018, "value" : 22.659 }, "1" : { "year" : 2017, "value" : 25.11 }, "2" : { "year" : "2016", "value" : 20.82 }, "3" : { "year" : 2015, "value" : 18.49 } } }

But always got the entire object and not only the History. Apparently used the wrong syntax as it is :

db.stockData.find( {}, {History:1}).forEach(function(doc) { 
printjson(doc.History);   } );

Of course it's doable. JavaScript is Turing complete. What have you tried? What problems did you encounter? Include your code. — Jonathan Hall, Jul 26 '19 at 13:52
Possible duplicate of [Converting JavaScript object with numeric keys into array](https://stackoverflow.com/questions/20881213/converting-javascript-object-with-numeric-keys-into-array) — adiga, Jul 26 '19 at 13:54
`Object.values(data.History)` or `Object.assign([], data.History)` — adiga, Jul 26 '19 at 13:57
Could you instead, tackle the problem at its roots and save the document directly as an array in Mongo? — Jeremy Thille, Jul 26 '19 at 13:59
`const updatedObj = Object.assign({}, obj, {History: Object.values(obj.History)});` — HynekS, Jul 26 '19 at 14:01
@Flimzy clarified what went wrong. I was looking at the wrong output. — Non Plus Ultra, Jul 26 '19 at 14:07

dganenco · Answer 1 · 2019-07-26T14:05:23.637

If you have to support IE browser too ,you have to use Array#map function.

const arr = {
  "History": {
    "0": {
      "year": 2018,
      "value": 22.659
    },
    "1": {
      "year": 2017,
      "value": 25.11
    },
    "2": {
      "year": 2016,
      "value": 20.82
    },
    "3": {
      "year": 2015,
      "value": 18.49
    }
  }
};

const res = Object.keys(arr.History).map(function(key){ 
return arr.History[key]});

console.log(res);

score 2 · Accepted Answer · answered Jul 26 '19 at 13:58

To convert an object with numerical keys to an array, you can use Object.values():

const obj = {"History":{"0":{"year":2018,"value":22.659},"1":{"year":2017,"value":25.11},"2":{"year":2016,"value":20.82},"3":{"year":2015,"value":18.49}}}

const result = Object.values(obj.History)

console.log(result)

score 0 · Answer 3 · answered Jul 26 '19 at 14:03

0

yes, it's doable in JavaScript using Object.values()

let obj = db.stockData.find({productcode:"EMIM.AS"},{History:1} )
let result = Object.values(obj.History)

it returns your target array.

answered Jul 26 '19 at 14:03

hesam rajaei

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How can I convert these json objects to a proper array?

3 Answers3