How to get specific values of an embedded document Array in MongoDB using Java Driver

Question

what I tried to is getting all sitename from every embedded documents in the array.I have tried using following syntax but didn't work

( sites.$.site )

{
  "user" : "username",
  "sites" : [{
      "sitename" : "site.com",
      "url" : "site.com",
      }, {
      "sitename" : "site2.com",
      "url" : "site2.com",
      },{
      "sitename" : "site2.com",
      "url" : "site2.com",
   }]
}

"sites.$.site" seems to be a typo. Surely "sites.sitename" ? — Vince Bowdren
– Vince Bowdren, Commented Mar 10, 2017 at 9:19
Possible duplicate of Search by element of an object in a array — Vince Bowdren
– Vince Bowdren, Commented Mar 10, 2017 at 9:22
Possible duplicate of Finding distinct from collections in mongodb. Use "sites.sitename" as name key in linked answer for your case. — s7vr
– s7vr, Commented Mar 10, 2017 at 10:36

radhakrishnan · Accepted Answer · 2017-03-10 09:56:13Z

1

Mongo-java,

        MongoClient mongoClient = new MongoClient("localhost",27017);
        MongoDatabase database = mongoClient.getDatabase("Test");

        MongoCollection<Document> collection = database.getCollection("collection");
        ArrayList<Document> doc = new ArrayList<Document>();
        doc.add(new Document().append("$unwind","$sites"));
        doc.add(new Document().append("$project",new Document().append("sitename","$sites.sitename")));
        List<Document> results =collection.aggregate(doc).into(new ArrayList<Document>());
        for(Document res: results){
            System.out.println(res.toJson());
        }

output:

        { "_id" : { "$oid" : "58c26ce044400b08ca6ff483" }, "sitename" : "site.com" }
        { "_id" : { "$oid" : "58c26ce044400b08ca6ff483" }, "sitename" : "site2.com" }
        { "_id" : { "$oid" : "58c26ce044400b08ca6ff483" }, "sitename" : "site2.com" }

answered Mar 10, 2017 at 9:56

radhakrishnan

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2 Comments

Amal Madawa Over a year ago

why do u use Document Instead of BasicDbObject ? i used BasicDbObject and did some changes. but it works thanks

radhakrishnan Over a year ago

from mongodb3.0 onwards MongoCollection insert ,update, qurery ,aggregate and most of methods accept only org.bson.Document

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