MongoDB - Filtering the content of an internal Array in a resultset

Question

I\'m new using MongoDB, and I don\'t know how to solve the next problem:

I have a collection of documents like this:

{
 \"URL\": \"www.stackoverflow.com\         


        

Answer 1

You can use aggregation framework of MongoDB.

If you have a doc in your collection like ;

{
 "URL": "www.stackoverflow.com",
 "TAGS": [
         {"NAME": "question", "VOTES": 3},
         {"NAME": "answer", "VOTES": 5},
         {"NAME": "problem", "VOTES": 2}
         ]
}

and you want to filter some elements of the array out you can use the aggregation sample;

db.sof_table.aggregate
([
{$unwind:'$TAGS'}, 
{$match:{'TAGS.NAME':{$in:['answer','question']}}},
{$group:{_id:'$URL',TAGS:{$push:'$TAGS'}}}
])

This will result;

{
    "result" : [
        {
            "_id" : "www.stackoverflow.com",
            "TAGS" : [
                {
                    "NAME" : "question",
                    "VOTES" : 3
                },
                {
                    "NAME" : "answer",
                    "VOTES" : 5
                }
            ]
        }
    ],
    "ok" : 1
}

as your expected result.