MongoDB Querying for object property in list

Question

Let's say I do have a document like this:

{
    _id: "cow",
    comments: [
        {user: "karl", comment: "I like cows.", at: /*a date*/},
        {user: "harry", comment: "Cows are the best.", at: /*a date*/}
    ]
}

Now I want to collect all the comments that "karl" left in my db. Or just the ones on a certain date. The "comments" are indexed, how can I query for that?

score 12 · Accepted Answer · answered Dec 17 '11 at 15:32

Something like:

db.foo.find({"comments.user":"karl", "comments.at":{$gt:{dateObject}});

Haven't tested but you get the idea; you can drill down on items as such.

I'd recommend going through this site as it drives you through a great deal of interactive tutorials: Interactive Tutorial

Felix Yan · Answer 2 · 2013-07-16T15:25:03.287

6

You should use $elemMatch to match more than one conditions in same doc.

Something like:

db.foo.find({comments: {"$elemMatch": {user: "karl", at: {$gt:{dateObject}}}})

See here for more details.

edited Jul 16 '13 at 15:25

answered Dec 17 '11 at 15:42

Felix Yan

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the mongodb website changed their documentation urls - anyway I updated my answer with something relevant on the new site. – Felix Yan Jul 16 '13 at 15:26

MongoDB Querying for object property in list

2 Answers2