Mongo数据库查询数组

Question

I have a document such as the following:

{
    "_id" : LUUID("8a831942-1dd6-1942-8759-c6275305d10d"),
    "Record" : "SEK_2Y_9Y",
    "RawDataDictionary" : [[ 1033, ""], [3355,""], [886,"45.8"],[874,"589"]],
    "TimeStamp" : ISODate("2015-02-10T16:27:14.847Z")
}

The "RawDataDictionary" contains pairs of code and value.

I want all the documents that their "RawDataDictionary" contains an item with 874 code and any value that is not null/Empty.

so [874,""] will not obey it but [874,"something"] will.

Any ideas ?

Doron.

Answer 1

I don't believe there is a way to express your condition on your document in the MongoDB query language (as of 2.6). The issue is that there's no way to express the "any [second] value that is not null/empty" condition.

db.test.find({ "RawDataDictionary" : [1033, ""] }) // ok

db.test.find({ "RawDataDictionary" : [874, { "$ne" : "" }) // nope

You can use $elemMatch to perform the query if you modify the structure of the RawDataDictionary field:

{
    "Record" : "SEK_2Y_9Y",
    "RawDataDictionary" : [
        { "code" : 1033, "value" : "" }, 
        { "code" : 3355, "value" : "" },  
        { "code" : 886, "value" : "45.8" }, 
        { "code" : 874, "value" : "589" }
    ],
    "TimeStamp" : ISODate("2015-02-10T16:27:14.847Z")
}

db.test.find({ "RawDataDictionary" : {
    "$elemMatch" : { 
        "code" : 874, 
        "value" : { "$nin" : ["", null] } 
    } 
} })