CODEWITHSUNDEEP
javamongodbaggregation-framework
Shilpa
Shilpa

Reputation: 101

MongoDb query to java code using aggregates

Can someone help me converting the below query to java code?

I have written the following query in java as below but am getting below error,

Command failed with error 168: 'Unrecognized expression '$push'' on server. The full response is { "ok" : 0.0, "errmsg" : "Unrecognized expression '$push'", "code" : 168, "codeName" : "InvalidPipelineOperator" }

Query:

db.getCollection('xyz').aggregate([
             {$match: { "_id":{$in: [{"a" : "NA","b" : "HXYZ","c" : "12345","d" : "CA"}]}
                     }
                   },
              { $unwind: '$bal' },
              {
                 $sort: {'bal.date': -1}
              },
              {$group:
                   {"_id": "$_id",bal:{$push:'$bal'}}},
               { $project: {
            balances: { $slice: ["$bal",2]} 
                            }
               }

       ])

Java Code:

List<Document> findDocument=collectionName.aggregate(
            Arrays.asList(
                Aggregates.match(in("_id",tempList)),
            Aggregates.unwind("$bal"),
            Aggregates.sort(Sorts.descending("bal.date")),
            Aggregates.group(new Document("_id","$_id").append("bal",new Document("$push","$bal"))),
        Aggregates.project(new Document("bal",new Document ("$slice",Arrays.asList("$bal", 2)))))).into(new ArrayList<Document>());

The Mongo DB version is 3.4. Can someone tell me why is $push not working ? Thanks in advance.

Upvotes: 0

Views: 1351

Answers (1)

s7vr
s7vr

Reputation: 75994

You are pushing the document into id field instead create push document separately.

import static com.mongodb.client.model.Accumulators.*;
import static com.mongodb.client.model.Aggregates.*;
import static com.mongodb.client.model.Filters.in;
import static com.mongodb.client.model.Sorts.*;
import static java.util.Arrays.*;
List<Document> results = collectionName.aggregate(
     asList(
          match(in("_id",tempList)),
          unwind("$bal"),
          sort(descending("bal.date")),
          group("$_id", push("bal","$bal")),
          project(new Document("bal",new Document ("$slice", asList("$bal", 2))))
    )
).into(new ArrayList<>());

Upvotes: 1

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