CODEWITHSUNDEEP
mongodbmongodb-javadbref
Jessie
Jessie

Reputation: 963

Mongodb java - how to query for particular reference id value

I have two collections

  checkone
    {"_id":1,"name":"alex"},
    {"_id":2,"name":"sandy"}
  checktwo
    {"_id":11,"password":"alex",tenant_id:{$ref:"checkone","$id":1}}
    {"_id":12,"password":"alex",tenant_id:{$ref:"checkone","$id":2}}

I am querying for particular field tenant_id value.

    DB database = mongo.getDB("testcheck");
    DBCollection tenant = database.getCollection("checktwo");
    BasicDBObject query = new BasicDBObject();
    BasicDBObject field = new BasicDBObject();
    field.put("tenant_id.$id", 1);
            DBCursor cursor = tenant.find(query,field);
                while (cursor.hasNext()) {
        System.out.println("cursor value");
        System.out.println(cursor.next().get("tenant_id.$id"));
    }

Output:

cursor value null cursor value null

But when I query System.out.println(cursor.next().get("_id"));

Output: cursor value 11.0 cursor value 12.0

How to query for tenant_id value alone? The output must be cursor value 1, cursor value 2

Upvotes: 0

Views: 2467

Answers (1)

slee
slee

Reputation: 534

You want to use the DBRef class. Here's a rewrite of your original while() loop.

    BasicDBObject query = new BasicDBObject();
    BasicDBObject field = new BasicDBObject();
    DBCursor cursor = tenant.find( query, field );

    while( cursor.hasNext() ) {
        System.out.println( "cursor value" );
        DBRef ref = ( DBRef )cursor.next().get( "tenant_id" );
        System.out.println( ref.getId() );
    }

Upvotes: 1

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