Question

Suppose I have the following schema:

"_id" : 1,
  "n" : [{
      "a" : ObjectId("4ef0ca414653b7c866040000"),
      "d" : new Date("Thu, 22 Dec 2011 04:53:56 GMT +04:00")
    }, {
      "a" : ObjectId("4ef0ca414653b9c866040000"),
      "d" : new Date("Thu, 22 Dec 2011 04:54:11 GMT +04:00")
    }, {
      "a" : ObjectId("4ef0ca424653b9c866040000"),
      "d" : new Date("Thu, 22 Dec 2011 04:54:30 GMT +04:00"),
   }]

and I need to remove all n, where d is less than specific date.

So I thought I will be able to do this in the following way:

db.coll.update({
'_id': 1
},{
 $pullAll : {
  n.d : {
     $lte : new Date(2000, 10, 11)
   }
 }
})

but the problem is, that it is not working this way.
Any suggestions?

Answer 1

That is not how $pullAll works. You cannot specify a matching condition, you can only specify an array of objects to be deleted (that need to match exactly).

Fortunately, you can use $pull instead (which does accept a matching condition):

db.coll.update({
'_id': 1
},{
 $pull : {
  n.d : {
     $lte : new Date(2000, 10, 11)
   }
 }
})

Note that $pull also pulls all elements that match, not just one.

This is admittedly a little confusing.