Find from another find in mongodb - mongodb

Question

In Mysql I can do a Select from another Select.
So I would ask if I can do the same in Mongodb.
For more explanation, I need to retreive the transaction of the a specific userOwner with just the last dateTransaction in the history object of this collection.So if this userOwner isn't in the last history we shoudn't retreive this transaction.
I used at first this query:
#Query(value = "{'history':{'$elemMatch':{'userOwner': ?0}}}")
but it returns all the elements even those where this userOwner isn't with the last "dateTransaction".
So I aim to de a query that it returns for each transaction just the last dateTransaction with userOwner of the "history" array :
.find({},{dateTransaction: {$slice: 1} }).limit(1)
and after do another query from this one.
Anyone has an idea or examples.
Tnx
This is my Collection called "piece":
{
"_id" : ObjectId("1"),
"history" : [{
"userOwner" : "3",
"dateTransaction" : ISODate("2016-05-30T00:00:00.000+0000"),
}, {
"userOwner" : "1",
"dateTransaction" : ISODate("2016-05-26T00:00:00.000+0000"),
}, {
"userOwner" : "2",
"dateTransaction" : ISODate("2016-05-23T00:00:00.000+0000"),
}
]
}{
"_id" : ObjectId("2"),
"transactions" : [{
"userOwner" : "2",
"dateTransaction" : ISODate("2016-05-26T00:00:00.000+0000"),
}, {
"userOwner" : "3",
"dateTransaction" : ISODate("2016-05-15T00:00:00.000+0000"),
}
]
}{
"_id" : ObjectId("3"),
"transactions" : [{
"userOwner" : "2",
"dateTransaction" : ISODate("2016-05-26T00:00:00.000+0000"),
}, {
"userOwner" : "1",
"dateTransaction" : ISODate("2016-05-15T00:00:00.000+0000"),
}
]
}
As example the result for the userOwner 2 should be :
{
"_id" : ObjectId("2"),
"transactions" : [{
"userOwner" : "2",
"dateTransaction" : ISODate("2016-05-26T00:00:00.000+0000"),
}, {
"userOwner" : "3",
"dateTransaction" : ISODate("2016-05-15T00:00:00.000+0000"),
}
]
}{
"_id" : ObjectId("3"),
"transactions" : [{
"userOwner" : "2",
"dateTransaction" : ISODate("2016-05-26T00:00:00.000+0000"),
}, {
"userOwner" : "1",
"dateTransaction" : ISODate("2016-05-15T00:00:00.000+0000"),
}
]
}

Answer 1

it looks like your data is stored in one collection - so this is a kind of bad design as it needs more overhead to work with....
below aggregation query which has a lookup to the same collection to match data for user:2
var unwind = {
$unwind : "$history"
}
var matchUser = {
$match : {
"history.userOwner" : "2"
}
}
var lookUp = {
$lookup : {
from : "shm",
localField : "userOwner",
foreignField : "userOwner",
as : "t"
}
}
var unwindTransactions = {
$unwind : "$t"
}
var unwindTransactions2 = {
$unwind : "$t.transactions"
}
var match2 = {
$match : {
"t.transactions.userOwner" : "2"
}
}
var project = {
$project : {
_id : 0,
recordId : "$_id",
transactionId : "$t._id",
dateOfTransaction : "$history.dateTransaction",
userOwner : "$history.userOwner",
}
}
db.shm.aggregate([unwind,
matchUser,
lookUp,
unwindTransactions,
unwindTransactions2,
match2,
project
])
and as a result we have two records of user transactions
{
"recordId" : ObjectId("575e7e8b852cb76369c9e446"),
"transactionId" : ObjectId("575e7e8b852cb76369c9e447"),
"dateOfTransaction" : ISODate("2016-05-23T00:00:00.000Z"),
"userOwner" : "2"
},{
"recordId" : ObjectId("575e7e8b852cb76369c9e446"),
"transactionId" : ObjectId("575e7e8b852cb76369c9e448"),
"dateOfTransaction" : ISODate("2016-05-23T00:00:00.000Z"),
"userOwner" : "2"
}
Please consider split of that collection as in current form will give you a lot of headache when processing more complex queries