Question

I want to pull a specific item from an embedded array…assume the following mongo document….

db.test.find()

{
  id:1,
  comments : 
   [
     { cid: 1 },
     { cid: 2 },
     { cid: 3 },
     { cid: 4 },
     { cid: 5 }
   ]
}

I want to remove an item from the comments array by cid, not by position. I’ve tried all of these but none of them appear to work. I’ve tried using the dot notation, but that does not seem to have any effect. I tried the last post suggestion from How to Delete-nth element from array, but no luck…

db.test.update({ 'comments.cid' : 5}, {"$pull" :{"comments":{"cid":"3"}}}    )
db.test.update(  {id: 1}, {"$pull" : {"comments" : { "cid" : "3"}}},false,false)
db.test.update(  {id: 1}, {"$pull" :{"comments.cid" :3}})

Answer 1

These worked too…

db.test.update({comments:{cid:4} }, 
                    {$pull:{comments:{cid:4}},  
                      $inc:{commentCount: -1}})

db.test.update({"comments.cid" : 17}, 
                     {$pull:{ comments:{cid: 17}}, 
                      $inc:{commentCount:-1}})