Cut data from array of JSON objects

Question

I have array of JSON objects like this:

[ { id: 841,
    when: 'date',
    who: 'asd',
    what: 'what',
    key1 : 'a key',
    key2 : 'a key'
    _id: 544034ab914ae3b9270545c1,
    __v: 0 }, 
{ id: 841,
    when: 'date',
    who: 'asd',
    what: 'what',
    key1 : 'a key',
    key2 : 'a key'
    _id: 544034ab914ae3b9270545c1,
    __v: 0 } ]

I want to cut key1 and key2from that objects and want to see this:

[ { id: 841,
    when: 'date',
    who: 'asd',
    what: 'what',
    _id: 544034ab914ae3b9270545c1,
    __v: 0 }, 
{ id: 841,
    when: 'date',
    who: 'asd',
    what: 'what',
    _id: 544034ab914ae3b9270545c1,
    __v: 0 } ]

How can I cut that keys and values?

My method is not working. (Pseudo) :

var new_array
for i  old_array.length
   delete old_array[i].key1  
   delete old_array[i].key2
new_array.push(old_array[i])

What exactly isn't working? This should be fine. But it's worth noting that you shouldn't need to create a new array. Delete edits the object in place, so if you delete the property from the object contained in the array, the original array should reflect those changes immediately — Brennan
– Brennan, Commented Oct 16, 2014 at 21:33
@Brennan I don't know but it's pushing old version of objects. By the way those are from a mongodb query, if it's matter. — Lazy
– Lazy, Commented Oct 16, 2014 at 22:04

jfornoff · Accepted Answer · 2014-10-16 22:05:40Z

1

yourArray = yourArray.map(function(current, index, arr){
  delete current.key1;
  delete current.key2;
  return current;
});

That should do what you wish ;-)

Hope that helps, Jan

edited Oct 16, 2014 at 22:05

answered Oct 16, 2014 at 21:33

jfornoff

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8 Comments

Mike Brant Over a year ago

More memory intensive than just deleting in place.

jfornoff Over a year ago

Thats true, thanks for pointing it out, Mike! You could do "delete arr[index].key1;" and same for key2.

Lazy Over a year ago

Thanks. I'm getting [ undefined, undefined ] with both of your methods. What can be caused to this?

jfornoff Over a year ago

Are you still reassigning the array like yourArray = yourArray.map(..)? It could be that this is the problem, in the memory-friendly version you just do yourArray.map(<in-place-deletion-method>)

jfornoff Over a year ago

OH NEVERMIND, you need to return current; after deleting the keys in my code above! I'll edit.

|

StackSlave · Accepted Answer · 2014-10-16 22:41:26Z

0

Like this:

function deleteProps(){
  var a = Array.slice(arguments) || Array.prototype.slice.call(arguments);
  var oa = a[0], dp = a.slice(1);
  for(var i=0,l=oa.length; i<l; i++){
    for(var n=0,c=dp.length; n<c; n++){
      delete oa[i][dp[n]];
    }
  }
  return oa;
}
var newObjectsArray = deleteProps(objectsArray, 'key1', 'key2');

edited Oct 16, 2014 at 22:41

answered Oct 16, 2014 at 22:27

StackSlave

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1 Comment

Lazy Over a year ago

TypeError: Object #<Object> has no method 'slice'. Thanks but there is a problem, it can't splice

Mike Brant · Accepted Answer · 2014-10-17 14:44:17Z

0

You pseudo-code is basically what you need, though you can just delete the properties in place:

var arr = [...]; // your array
for (var i = 0; i < arr.length; i++) {
    delete arr[i].key1;
    delete arr[i].key2;
}

edited Oct 17, 2014 at 14:44

answered Oct 16, 2014 at 21:40

Mike Brant

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6 Comments

Lazy Over a year ago

This method wasn't working and I couldn't find why. Thank you. @Mike Brant

jfornoff Over a year ago

Lets nitpick a bit, should be var i = 0 ;-)

StackSlave Over a year ago

... and array is undefined.

Mike Brant Over a year ago

@Lazy Fixed my dumb variable naming problem :) This should work for you now.

Lazy Over a year ago

Thank you. I solved this problem using _.omit feature of underscore.js.

|

Lazy · Accepted Answer · 2014-10-20 20:58:35Z

0

I used underscore.js

var cutted_object =  _.omit(json_object, "key1", "key2" 
                                         "key2", "date",
                                         "id33", "etc");

answered Oct 20, 2014 at 20:58

Lazy

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