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how to give $toObjectId in Java Mongo Projection Operation

I am new bee to mongo. Below is the Aggregation operation I am doing in mongodb shell . But In my java ProjectionAggregation , am not able to give the $toObjectId. Please correct me what am I missing.
db shell query
db.getCollection('UserData').aggregate([
{
$project : {
"username" : "$username",
"beneficiaries" : "$beneficiaries"
}
},
{
$unwind : {
path : "$beneficiaries",
preserveNullAndEmptyArrays: true
}
},
{
$project : {
"username" : "$username",
"beneficiaries" : "$beneficiaries",
---- dont know how to give $toObjectId in java ProjectionOperation .
"beneficiaryStudId" : { $toObjectId : "$beneficiaries.studentId" }
}
},
{
$lookup:
{
from: "StudentProfileData",
localField: "beneficiaryStudId",
foreignField: "_id",
as: "studProfile"
}
}
])
Java code Projection Operation
ProjectionOperation projectUserAndBeneficiaries = Aggregation.project()
.andExpression("username").as("username")
.andExpression("beneficiaries").as("beneficiaries");
ProjectionOperation projectUserAndOtherDetails = Aggregation.project()
.andExpression("username").as("username")
.andExpression("beneficiaries").as("beneficiaries")
---- How to give $toObjectId in projection operation .andExpression("beneficiaries.studentId").as("beneficiaryStudId");
LookupOperation lookupOperation = LookupOperation.newLookup().
from("StudentProfileData").
localField("beneficiaryStudId").
foreignField("_id").
as("studProfile");
Aggregation agg = Aggregation.newAggregation(projectUserAndBeneficiaries, unwindBeneficiars,
projectUserAndOtherDetails
,lookupOperation);
AggregationResults<UserAndStudentData> output
= mongotemplate.aggregate(agg, "UserData", UserAndStudentData.class);
Sample Ouput
Output in db shell
{
"_id" : ObjectId("5d2f08574de2690001c281ac"),
"username" : "ks241#goo.com",
"beneficiaries" : {
"studentId" : "5d2f0e9c3bcf3e0001a7e562",
"mcBeneficiaryId" : "597418",
"enabled" : true
},
"beneficiaryStudId" : ObjectId("5d2f0e9c3bcf3e0001a7e562"),
"studProfile" : [
{
"_id" : ObjectId("5d2f0e9c3bcf3e0001a7e562"),
"lastName" : "Sharma",
"firstName" : "Kapil",
"studentRegisterCustomFieldValues" : [
{
"bcfdValue" : "One",
"bcfdName" : "Year"
}
],
"gender" : "M",
"merchantId" : "38788943"
}
]
}
where as in java
the studProfile array is always empty if I add $toObjectId the above java aggregation projection query and ran it produces the values as same as that db shell .

Spring data doesn't support to few type of methods. This problem may include into it. But we may use this solution.
Aggregation aggregation=newAggregation(
p-> new Document("$project",
new Document()
.append("username","$username"),
.append("beneficiaries","$beneficiaries)
.append("beneficiaryStudId",
new Document("$toObjectId","$beneficiaries.studentId")
)
)
)

There is a way to do this with Spring's ProjectionOperation and ConvertOperators classes:
ProjectionOperation projection = Aggregation.project()
.andInclude("username", "beneficiaries")
.and(ConvertOperators.ToObjectId.toObjectId("$beneficiaries.studentId"))
.as("beneficiaryStudId");

Morphia query date range

What is the equivalent of the following Mongo query in Morphia?
db.events.find({ "date": { $gte: ISODate("2001-01-01") , $lt: ISODate("2001-01-02")} })
Currently I have the following code
Query<Event> query = dataStore.find(Event.class);
query.field("date").greaterThanOrEq(startDate).field("date").lessThan(endDate);
but it results in the following Mongo query
{ "$and" : [ { "date" : { "$gte" : { "$date" : "2001-01-01T00:00:00.000Z"}}} , { "date" : { "$lt" : { "$date" : "2001-01-02T00:00:00.000Z"}}}]}
I suppose the end result is the same, but the resulting query is more verbose.

Use criteria with add method
Something like
Query<Event> query = datastore.find(Event.class);
query.criteria("date").greaterThanOrEq(startDate).add(query.criteria("date").lessThan(endDate));

You need to create a query then add date range condition like followed.
Query<Event> queryForEvent = ds.createQuery(Event.class);
queryForEvent.field("date").greaterThanOrEq(startDate);
queryForEvent.field("date").lessThan(endDate);
List<Event> eventList = queryForEvent.asList();
Hoping you will find it useful.

Aggregation using MongoDB java driver

I'm using MongoDB java driver 3.2.2 to do some aggregation operations, but I'm not sure if something could be achieved through it.
The original query in MongoDB is:
db.getCollection('report').aggregate({
$group: {
_id: "$company_id",
count: {
$sum: {
$cond: [{
$eq: ["$idcard.status", "normal"]
},0,1]
}
}
}
})
I have no idea of how to put the "$cond" as a parameter of "$sum" operator in Java driver in the code section below:
AggregateIterable<Document> res = col.aggregate(Arrays.asList(
group("$company_id",
sum("count", ...)
)));
I've searched the official document about this with no result, anyone has experience of doing this? Thanks.

For 3.x drivers
Using BsonDocument : Type Safe Version
BsonArray cond = new BsonArray();
BsonArray eq = new BsonArray();
eq.add(new BsonString("$idcard.status"));
eq.add(new BsonString("normal"));
cond.add(new BsonDocument("$eq", eq));
cond.add(new BsonInt64(0));
cond.add(new BsonInt64(1));
AggregateIterable<BsonDocument> aggregate = dbCollection.aggregate(Arrays.asList(
group("$company_id",
sum("count", new BsonDocument("$cond", cond))
)));
Using Document - Less Code but Not Type Safe
List cond = new ArrayList();
cond.add(new Document("$eq", Arrays.asList("$idcard.status", "normal")));
cond.add(0);
cond.add(1);
AggregateIterable<Document> aggregate = dbCollection.aggregate(Arrays.asList(
group("$company_id",
sum("count", new Document("$cond", cond))
)));

To use $cond in Java use ArrayList.
{ $cond: [ { $eq: ["$idcard.status", "normal"] },0,1]
// To Acheive this - [ "$idcard.status", "normal" ]
ArrayList eqArrayList = new ArrayList();
eqArrayList.add("$idcard.status");
eqArrayList.add("normal");
// To Acheive this - [ { $eq: [ "$idcard.status", "normal" ] } , 1, 0 ]
ArrayList condArray = new ArrayList();
condArray.add(new BasicDBObject("$eq", eqArrayList));
condArray.add(1);
condArray.add(0);
// Finally - { $cond: [ { $eq: ["$idcard.status", "normal" ] } , 1, 0 ] }
BasicDBObject fullCond = new BasicDBObject("$cond", condArray);
Also see: MongoDB aggregation condition translated to JAVA driver

Spring Data Mongo Template - Counting an array

Mongo document:
{
"_id" : "1",
"array" : [
{
"item" : "item"
},
{
"item" : "item"
}
]
}
My mongo shell query looks like so:
db.getCollection('collectionName').aggregate(
{$match: { _id: "1"}},
{$project: { count: { $size:"$array" }}}
)
Is there anyway to implement this using the Mongo Template from Spring?
So far I have this:
MatchOperation match = new MatchOperation(Criteria.where("_id").is("1"));
ProjectionOperation project = new ProjectionOperation();
Aggregation aggregate = Aggregation.newAggregation(match, project);
mongoTemplate.aggregate(aggregate, collectionName, Integer.class);
I think I am only missing the project logic but I'm not sure if it is possible to do $size or equivalent here.

It's quite possible, the $size operator is supported (see DATAMONGO-979 and its implementation here). Your implementation could follow this example:
import static org.springframework.data.mongodb.core.aggregation.Aggregation.*;
Aggregation agg = new Aggregation(
match(where("_id").is("1")), //
project() //
.and("array") //
.size() //
.as("count")
);
AggregationResults<IntegerCount> results = mongoTemplate.aggregate(
agg, collectionName, Integer.class
);
List<IntegerCount> intCount = results.getMappedResults();

Please find below the sample code. You can change it accordingly for your requirement with collection name, collection name class and array field name.
MatchOperation match = new MatchOperation(Criteria.where("_id").is("1"));
Aggregation aggregate = Aggregation.newAggregation(match, Aggregation.project().and("array").project("size").as("count"));
AggregationResults<CollectionNameClass> aggregateResult = mongoOperations.aggregate(aggregate, "collectionName", <CollectionNameClass>.class);
if (aggregateResult!=null) {
//You can find the "count" as an attrribute inside "result" key
System.out.println("Output ====>" + aggregateResult.getRawResults().get("result"));
System.out.println("Output ====>" + aggregateResult.getRawResults().toMap());
}
Sample output:-
Output ====>[ { "_id" : "3ea8e671-1e64-4cde-bd78-5980049a772b" , "count" : 47}]
Output ====>{serverUsed=127.0.0.1:27017, waitedMS=0, result=[ { "_id" : "3ea8e671-1e64-4cde-bd78-5980049a772b" , "count" : 47}], ok=1.0}

You can write query as
Aggregation aggregate = Aggregation.newAggregation(Aggregation.match(Criteria.where("_id").is(1)),
Aggregation.project().and("array").size().as("count")); mongoTemplate.aggregate(aggregate, collectionName, Integer.class);
It will execute the following query { "aggregate" : "collectionName" , "pipeline" : [ { "$match" : { "_id" : 1}} , { "$project" : { "count" : { "$size" : [ "$array"]}}}]}

Mongodb Java driver use limit in aggregation query

Problem
Query is working fine but not limit and skip, it is fetching all records at once.
Kindly suggest what I am doing wrong.
MongoDB Collection
{
"_id" : ObjectId("559666c4e4b07a176940c94f"),
"postId" : "559542b1e4b0108c9b6f390e",
"user" : {
"userId" : "5596598ce4b07a176940c943",
"displayName" : "User1",
"username" : "user1",
"image" : ""
},
"postFor" : {
"type": "none",
"typeId" : ""
},
"actionType" : "like",
"isActive" : 1,
"createdDate" : ISODate("2015-07-03T10:41:07.575Z"),
"updatedDate" : ISODate("2015-07-03T10:41:07.575Z")
}
Java driver Query
Aggregation aggregation = newAggregation(
match(Criteria.where("isActive").is(1).and("user.userId").in(feedUsers)),
group("postId")
.last("postId").as("postId")
.last("postFor").as("postFor")
.last("actionType").as("actionType")
.last("isActive").as("isActive")
.last("user").as("user")
.last("createdDate").as("createdDate")
.last("updatedDate").as("updatedDate"),
sort(Sort.Direction.DESC, "createdDate")
);
aggregation.skip( skip );
aggregation.limit( limit );
AggregationResults<UserFeedAggregation> groupResults =
mongoOps.aggregate(aggregation, SocialActionsTrail.class, UserFeedAggregation.class);
return groupResults.getMappedResults();
Thanks

Aggregation pipelines are "sequential" in operation. These are not like .find() operations where .sort() .limit() .skip() are "modifiers" to the query operation:
Aggregation aggregation = newAggregation(
match(Criteria.where("isActive")
.is(1).and("user.userId").in(feedUsers)),
group("postId")
.last("postId").as("postId")
.last("postFor").as("postFor")
.last("actionType").as("actionType")
.last("isActive").as("isActive")
.last("user").as("user")
.last("createdDate").as("createdDate")
.last("updatedDate").as("updatedDate"),
sort(Sort.Direction.DESC, "createdDate"),
skip( skip ),
limit( limit )
);
Unless you define the operations in "sequence" then the pipeline does not know the order of execution. So define the pipeline as a whole.
A basic example:
Aggregation aggregation = newAggregation(
group("postId"),
skip(1),
limit(1)
);
System.out.println(aggregation)
Outputs a perfect pipeline:
{
"aggregate" : "__collection__" ,
"pipeline" : [
{ "$group" : { "_id" : "$postId" } },
{ "$skip" : 1 },
{ "$limit" : 1 }
]
}
See $skip and $limit in the core documentation.