Match Documents based on Nested Array Values and Count Unique - mongodb

Question

I have a MongoDB Collection which has Documents in Given format,
{
"_id" : ObjectId("595f5661f34ae7b2adee31bc"),
"app_userUpdatedOn" : "2017-03-09T12:01:07.615Z",
"appId" : 31625,
"app_lastCommunicatedAt" : "2017-03-09T12:18:53.067Z",
"currentDate" : "2017-03-09T12:19:28.626Z",
"objectId" : "58c14850e4b0b2406992b29e",
"name" : "APPSESSION",
"action" : "START",
"installationId" : "98088f6641a0fa79",
"userName" : "98088f6641a0fa79",
"properties" : [
[
"userid",
"98088f6641a0fa79"
],
[
"app_os_version",
"6.0.1"
],
[
"app_installAt",
"2017-03-09T12:01:01.307Z"
],
[
"app_model",
"SM-J210F"
],
[
"app_lastCommunicatedAt",
"2017-03-09T12:18:53.067Z"
],
[
"app_carrier",
"Jio 4G"
],
[
"app_counter",
1
],
[
"app_brand",
"samsung"
],
[
"app_lib_version",
"1.0"
],
[
"app_app_version",
"3.0.2"
],
[
"app_os",
"Android"
]
],
"date" : "2017-03-09"
}
{
"_id" : ObjectId("595f5661f34ae7b2adee31bd"),
"app_userUpdatedOn" : "2017-02-05T07:38:32.866Z",
"appId" : 31625,
"app_lastCommunicatedAt" : "2017-03-09T08:09:05.342Z",
"currentDate" : "2017-03-09T12:19:28.806Z",
"objectId" : "58c14850e4b06ec88ecaa9c6",
"name" : "APPINSTALL",
"action" : "START",
"installationId" : "eef436554fbdf4ac",
"userName" : "eef436554fbdf4ac",
"properties" : [
[
"userid",
"eef436554fbdf4ac"
],
[
"app_os_version",
"5.1"
],
[
"app_installAt",
"2017-02-05T11:20:49.809Z"
],
[
"app_model",
"Micromax Q465"
],
[
"app_lastCommunicatedAt",
"2017-03-09T08:09:05.342Z"
],
[
"app_carrier",
"JIO 4G"
],
[
"app_counter",
1
],
[
"app_brand",
"Micromax"
],
[
"app_lib_version",
"1.0"
],
[
"app_app_version",
"3.0.2"
],
[
"app_os",
"Android"
]
],
"date" : "2017-03-09"
}
I want to Fetch the Count and Unique Count of the Documents where currentDate lies in between, startDate and endDate, name is x (eg. APPSESSION), Containing multiple Properties Nested Array (like ["app_installAt","This can be any value instead of null"] ,["app_model","This can be any value instead of null"], and so on... ), Group By userName
Previously i have created a Query in which Nested Array Both Element are Known, and it is as follows
db.testing.aggregate(
[
{$match: {currentDate: {$gte:"2017-03-01T00:00:00.000Z", $lt:"2017-03-02T00:00:00.000Z"},name:"INSTALL"}},
{$match: {properties: ["app_os_version","4.4.2"]}},
{$match: {properties: ["app_carrier","telenor"]}},
{$match: {properties: ["app_brand","Micromax"]}},
{$group: {_id: "$userName"}},
{$count: "uniqueCount"}
]
);
But i am unable to find the Data where i know only 0th index of Property Data Nested Array.
Please do Help.
Thanks in Advance.... :)

Answer 1

The query for this is essentially the use of $all for the multiple conditions to match in the array and then use $elemMatch and $eq to match the individual array elements.
For example to match and count the first document supplied in your question "only" the parameters would be:
db.testing.find({
"currentDate": {
"$gte": "2017-03-09T00:00:00.000Z",
"$lt": "2017-03-10T00:00:00.000Z"
},
"properties": {
"$all": [
{ "$elemMatch": { "$eq": ["app_os_version","6.0.1"] } },
{ "$elemMatch": { "$eq": ["app_carrier", "Jio 4G"] } },
{ "$elemMatch": { "$eq": ["app_brand", "samsung"] } }
]
}
})
With .aggregate() then you put the whole query into a single $match stage as in:
db.testing.aggregate([
{ "$match": {
"currentDate": {
"$gte": "2017-03-09T00:00:00.000Z",
"$lt": "2017-03-10T00:00:00.000Z"
},
"properties": {
"$all": [
{ "$elemMatch": { "$eq": ["app_os_version","6.0.1"] } },
{ "$elemMatch": { "$eq": ["app_carrier", "Jio 4G"] } },
{ "$elemMatch": { "$eq": ["app_brand", "samsung"] } }
]
}
}},
{ "$group": { "_id": "$userName" }
{ "$count": "unique_count"
])
So $elemMatch in this context is going to examine each "inner" array and see if it matches the supplied conditions, which we give in argument as an "array" to the $eq operator.
The wrapping $all means that "all" the provided $elemMatch conditions "must" be met in order to fulfill the query conditions. And that is how the selection gets made with this type of structure.
If you needed to adjust one of those then the "inner" match is using the element of the array. So on the key it would use the "0" for the index position. i.e:
{ "$elemMatch": { "0": "app_os_version" } },