mongodb push element into array of objects

Question

I have a collection with a following schema:

{
  "_id" : ObjectId("4ee3ddc346b3b8880a000000"),
  ...
  "msgs" : [{
      "mid" : ObjectId("4ee3ddc346b3b8880a000000"),
      "deleted" : []
    },
    {
      "mid" : ObjectId("4ee3ddc346b3b8880a000100"),
      "deleted" : []
    }]
}

I want to do this query: for the specific _id insert into each "deleted" array an element

so after doing this query I will receive something like this:

{
  "_id" : ObjectId("4ee3ddc346b3b8880a000000"),
  ...
  "msgs" : [{
      "mid" : ObjectId("4ee3ddc346b3b8880a000000"),
      "deleted" : [2]
    },
    {
      "mid" : ObjectId("4ee3ddc346b3b8880a000100"),
      "deleted" : [2]
    }]
}

What I tried to do:

db.dialogs.update(
{ "_id" : ObjectId("4ee3ddc346b3b8880a000000")},
{$addToSet : {'msgs.$.deleted' : 2}}
)

the problem is that it only updating the first element element in the array, instead of all the elements

Any ideas?

Possible duplicate of : http://stackoverflow.com/questions/4669178/how-to-update-multiple-array-elements-in-mongodb — DhruvPathak, Dec 11 '11 at 19:24

score 1 · Answer 1 · answered Dec 11 '11 at 16:29

1

Specify the multiple update option:

db.dialogs.update(
  { "_id" : ObjectId("4ee3ddc346b3b8880a000000")},
  {$addToSet : {'msgs.$.deleted' : 2}},
  false,
  true
)

The last parameter true tells mongodb to update all matching documents. (the third parameter tells mongodb not to do upset).

PS: the above assumes your original query and $ operation is correct, I didn't confirm that in MongoDB.

answered Dec 11 '11 at 16:29

James Chen

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incorrect. What he wants here is to update several elements of a single document. Not all matching documents. – DhruvPathak Dec 11 '11 at 19:22

mongodb push element into array of objects

1 Answers1