How to remove JSON elements which are "" (Empty Strings)?

Question

I have a JSON in javascript. That contains such values as {id:""}. I need to drop those kind of values from the JSON object. Is there a simple way to do it?

If you need to find them too, recurse with for..in and hasOwnProperty — Paul S.
– Paul S., Commented Apr 28, 2014 at 11:28
don't remove but add if statement while coding. like this: if(obj.id.length !== 0){}. — Mr_Green
– Mr_Green, Commented Apr 28, 2014 at 11:41

mvw · Accepted Answer · 2014-04-28 12:55:17Z

A Json object is tree-like. You can use such a recursive function to walk and clean it:

function walkclean(x) {
  var type = typeof x;
  if (x instanceof Array) {
    type = 'array';
  }
  if ((type == 'array') || (type == 'object')) {
    for (k in x) {
      var v = x[k];
      if ((v === '') && (type == 'object')) {
        delete x[k];
      } else {
        walkclean(v);
      }
    }
  }
}

How to use the above code within the MongoDB shell:

var test = {
  a: "foo",
  b: [ "hi", "you", "", "ouch", "", "again!"],
  c: [ { nasty: "me", hit: "", whatever: [ "yeah" ] }, 
       { ha: { my: "", oh: "yeah", foo: ""}} ],
  d: "",
  e: 42
};

printjson(test);
walkclean(test);

print('=>');
printjson(test);

Result:

snippets/walkclean$ mongo walkclean.js
MongoDB shell version: 2.4.10
connecting to: test
{
    "a" : "foo",
    "b" : [
            "hi",
            "you",
            "",
            "ouch",
            "",
            "again!"
    ],
    "c" : [
            {
                    "nasty" : "me",
                    "hit" : "",
                    "whatever" : [
                            "yeah"
                    ]
            },
            {
                    "ha" : {
                            "my" : "",
                            "oh" : "yeah",
                            "foo" : ""
                    }
            }
    ],
    "d" : "",
    "e" : 42
}

=>

{
    "a" : "foo",
    "b" : [
            "hi",
            "you",
            "",
            "ouch",
            "",
            "again!"
    ],
    "c" : [
            {
                    "nasty" : "me",
                    "whatever" : [
                            "yeah"
                    ]
            },
            {
                    "ha" : {
                            "oh" : "yeah"
                    }
            }
    ],
    "e" : 42
}

I modified it so it skips zero length entries in string arrays.

Lix · Accepted Answer · 2014-04-28 11:27:16Z

2

You can use the delete command.

delete obj.id;

From the documentation:

delete
The delete operator removes a property from an object.

What you would want to do is iterate over all the objects in your JSON and when you detect an empty id attribute obj.id == "", you'll execute the delete command.

If you have multiple properties that you want to delete, you'll have to iterate over each one and test it against an empty string. If you are not sure how many attributes you'll want to remove then you'll simply have to iterate over each attribute for each object.

answered Apr 28, 2014 at 11:27

Lix

48.2k12 gold badges107 silver badges134 bronze badges

Collectives™ on Stack Overflow

How to remove JSON elements which are "" (Empty Strings)?

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related