mongodb pull element from array

Question

I have the following schema:

{
  "_id" : 27,
  "n" : [{
      "d" : new Date("Sat, 24 Dec 2011 17:03:00 GMT +04:00"),
      "e" : ObjectId("4f0aef5346b3b88013000001"),
      "f" : [26, 10, 16],
      "k" : new Date("Mon, 09 Jan 2011 17:44:51 GMT +04:00"),
      "t" : "f",
      "u" : 10
    }, {
      "a" : ObjectId("4f0c208846b3b8140f000000"),
      "d" : new Date("Tue, 10 Jan 2012 15:27:21 GMT +04:00"),
      "p" : [ObjectId("4f0c209046b3b8340f000000"), ObjectId("4f0c209346b3b8340f000001"), ObjectId("4f0c209646b3b8340f000002"), ObjectId("4f0c209946b3b8340f000003")],
      "t" : "p",
      "u" : 10
    }]
}

and this query removes all of the sub elements if at least one satisfy it

db.newsFeed.update({ "_id" : 27, },{
$pull : {
 'n' : {
    'd' : {
        $lte : new Date(2012, 1, 1)
        }
    }
}
});

so the document becomes like this, { "_id" : 27, "n" : [] }

what am I doing wrong, and more important what should I do to pull just some of the elements?

Tim Gautier · Accepted Answer · 2012-02-11 00:16:33Z

2

I think your query is fine, the problem is the date you're using.

Instead of:

new Date(2012, 1, 1)

Try:

ISODate("2012-01-01")

Try typing them in the shell by themselves and you'll get back these results:

> new Date(2012, 1, 1)
ISODate("2012-02-01T07:00:00Z")

> ISODate("2012-01-01")
ISODate("2012-01-01T00:00:00Z")

At least, that's what I see in my shell. Using the "new" returns a date that matches on both elements of your array, so they're both removed. Using ISODate directly creates the date object you're looking for and only matches on the first result.

The Date constructor takes a zero based month, so you want this if you want to use new:

new Date(2012, 0, 1)

edited Feb 11, 2012 at 0:16

answered Feb 11, 2012 at 0:09

Tim Gautier

30.3k5 gold badges50 silver badges53 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

mongodb pull element from array

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related