How to remove subdocument in mongoose?

Question

i have a collection which have many document each of which have a subdocument array

comment : {
  _id : ObjectId
  name : String,
  comments : [commentSchema]
}

commentSchema : {
  _id : ObjectId,
  commentType : String // can be either 'string' or 'image'
  commentData : String
}

Now i want to delete all the subdocuments in path of 'comments', which is of commentType = 'image', from the whole comment collection.

I have done the following

export.removeComments = function(next) {
    mongoose.model('comment').find({}, function(err,docs){
              if(err) return next(err);
              docs.forEach(function(doc, index){
                doc.comments.pull({ commentType : 'image'});

                //Following also not works
                /*  var comments = doc.comments;
                for(var i =0; i < comments.length; i++ ) {
                  if(comments[i].commentType == 'image')
                    doc.comments.remove(comments[i]._id);
                }*/

                if(index < docs.length - 1) doc.save();
                else doc.save(next);
              });
            });
};

But above has no effect.

Any help??

Answer 1

The following worked for me :

just added toString() with corresponding subdocument id as it was an Object not a string. and perhaps removing subdocument requires string of the id. Correct me if i am wrong.

mongoose.model('comment').find({}, function(err,docs){
              if(err) return next(err);
              docs.forEach(function(doc, index){

                for(var i =0; i < comments.length; i++ ) {
                  if(comments[i].commentType == 'image')
                    doc.comments.remove(comments[i]._id.toString());
                }

                if(index < docs.length - 1) doc.save();
                else doc.save(next);
              });
            });