Mongodb Embedded document querying

Question

Hi i have a data model like this

module{
    name: "xx",
    sa: [
        {
            sa_name: "yy",
            fact: [
                fact_name: "zz"
            ],
            dim: [
                dim_name: "qq"
            ]
        }
    ]
}

I have sa embedded in module and fact and dim embedded inside sa.

I tried db.coll.find({"module.sa.fact.name":"zz"},{}) is not working where as for single nest db.coll.find({"module.sa.name":"yy"},{}) is working fine. How can i query this sub document inside sub document.

The document is invalid, an array cannot directly contain fields, i.e. fact : [ fact_name : "zz" ] should be fact : [ { fact_name : "zz" } ] — mnemosyn
– mnemosyn, Commented Dec 11, 2013 at 12:43

Parvin Gasimzade · Accepted Answer · 2013-12-11 12:30:39Z

5

Update your query as :

db.coll.find({"module.sa" : {$elemMatch : {"fact.fact_name": "zz"}}})

answered Dec 11, 2013 at 12:30

Parvin Gasimzade

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1 Comment

mnemosyn Over a year ago

This works, but it solves the problem by fixing the typo(s), not because of $elemMatch. In fact, $elemMatch is designed for matching multiple criteria on a single array element which is not required here. Also, note that this still uses a multikey because in the OP's schema fact is an array itself, so it's arguable where one would want to use the $elemMatch.

chk · Accepted Answer · 2013-12-11 12:36:29Z

For me the query is just working fine, see mongo 2.4.8 shell:

> db.coll.insert({module: {name:"xx", sa: [{sa_name:"yy", fact:[{fact_name:"zz"}], dim:[{dim_name:"qq"}]}]}})
> db.coll.findOne()
{
        "_id" : ObjectId("52a85b44fd0b335ab0546ca4"),
        "module" : {
                "name" : "xx",
                "sa" : [
                        {
                                "sa_name" : "yy",
                                "fact" : [
                                        {
                                                "fact_name" : "zz"
                                        }
                                ],
                                "dim" : [
                                        {
                                                "dim_name" : "qq"
                                        }
                                ]
                        }
                ]
        }
}
> db.coll.findOne({"module.sa.fact.fact_name":"zz"})
{
        "_id" : ObjectId("52a85b44fd0b335ab0546ca4"),
        "module" : {
                "name" : "xx",
                "sa" : [
                        {
                                "sa_name" : "yy",
                                "fact" : [
                                        {
                                                "fact_name" : "zz"
                                        }
                                ],
                                "dim" : [
                                        {
                                                "dim_name" : "qq"
                                        }
                                ]
                        }
                ]
        }
}

Could it be that you're just having problems with some sort of typo as you're querying for "module.sa.fact.name" where it should be "module.sa.fact.fact_name". However, this problem is also true for the query which seems to work for you...

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