Multiple $elemMatch expressions for matching array values using $all in MongoDB?

Question

In the answer to a question I found a interesting solution for searching array values using $elemMatch.

If we have the following documents in our collection:

{
    foo : [ { bar : "xy", baz : 1 },
            { bar : "a", baz : 10 } ]
},
{
    foo : [ { bar : "xy", baz : 5 },
            { bar : "b", baz : 50 } ]
}

The following query will match only the first document:

db.test.find({
    foo : { "$all" : [ { "$elemMatch" : { bar : "xy", baz : 1} }, { "$elemMatch" : { bar : "a", baz : 10 } } ] }
});

I tried it with several other examples and it really works. But the official documentation for $all operator doesn't say anything about combining these two queries.

Is this the intended behavior or a bug? Or is this just a problem that the documentation does not cover this use case?

score 8 · Accepted Answer · answered Mar 22 '12 at 15:51

8

This is the intended behavior. The documentation doesn't cover this use case and we are working on it to make it better. Its difficult, however, to document every possible query combination.

answered Mar 22 '12 at 15:51

Sid

954
6
7

3

Thank for the info. I understand that it's hard to document every combination but it would be very useful to know that some of the operators can be combined. – Christian P Mar 22 '12 at 16:05
Is there any way to do this yet? – Ed Knowles Aug 03 '14 at 10:11

Multiple $elemMatch expressions for matching array values using $all in MongoDB?

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