MongoDB - how to query for a nested item inside a collection?

mongodb

Solution

Use dot notation (e.g. `advertisers.name`) to query and retrieve fields from nested objects:

db.agencies.find({
 "advertisers.created_at": {
   $gte: start,
   $lt: end
  }
 },
{
 _id: 1,
  program_ids: 1,
  "advertisers.name": 1
 }
}).limit(1).toArray();

Reference: Retrieving a Subset of Fields and Dot Notation

Problem

I have some data that looks like this: ``` [ { "_id" : ObjectId("4e2f2af16f1e7e4c2000000a"), "advertisers" : [ { "created_at" : ISODate("2011-07-26T21:02:19Z"), "category" : "Infinity Pro Spin Air Brush", "updated_at" : ISODate("2011-07-26T21:02:19Z"), "lowered_name" : "conair", "twitter_name" : "", "facebook_page_url" : "", "website_url" : "", "user_ids" : [ ], "blog_url" : "", }, ``` and I was thinking that a query like this would give the id of the advertiser: ``` var start = new Date(2011, 1, 1); > var end = new Date(2011, 12, 12); > db.agencies.find( { "created_at" : {$gte : start , $lt : end} } , { _id : 1 , program_ids : 1 , advertisers { name : 1 } } ).limit(1).toArray(); ``` But my query didn't work. Any idea how I can add the fields inside the nested elements to my list of fields I want to get? Thanks!

Original source