How can I retrieve a list of values of a field of a document in mongodb using java?

Question

I wish to retrieve the values of "comment" field in a String array or ArrayList (Java). Please refer to the image link or the following mongodb entry specified:

{ 
"_id" : ObjectId("56740295f0a1e82444261cd4"), 
"Title" : "Campus", 
"Description" : "Nice",
"City" : "Delhi",
"Venue" : "Paschim Vihar",
"Lab" : "Lab1",
"Tags" : [ "people", " building" ],
"UploadDate" : ISODate("2015-12-18T12:56:51.589Z"),
"MediaCreationDate" : ISODate("0015-01-09T18:41:00Z"),
"Likes" : 0,
"Dislikes" : 0,
"Video Hash" : "56740295f0a1e82444261cd4157",
"Url" : "56740295f0a1e82444261cd4157",
"comments" : [ "Hello Sir", "Hello World" ] 
}

Just a beginner. Thanks.

Not sure where exactly you need help.. Reading the data or converting them. To convert from Array to List, look at this: [Create ArrayList from array](http://stackoverflow.com/questions/157944/create-arraylist-from-array) — JoGe, Dec 18 '15 at 13:43

score 0 · Answer 1 · answered Dec 18 '15 at 14:30

Firstly, you need to add in your application mongodb driver. For example, for maven:

     <dependency>
        <groupId>org.mongodb</groupId>
        <artifactId>mongo-java-driver</artifactId>
        <version>3.1.0</version>
    </dependency>

Then you need to write code like this:

import static com.mongodb.client.model.Filters.*;

public class FindTest {
    public static void main(String[] args)  {
        //Connect to your mongodb instance
        MongoClient client = new MongoClient();

        //Connect to your database
        MongoDatabase db = client.getDatabase("try123");

        //Connect to your collection
        MongoCollection<Document> collection = db.getCollection("one");

        //Execute query to database
        List<Document> myDocs = collection.find(eq("Title", "Campus")).projection( Projections.include("comments")).into(new ArrayList<Document>());

        //Print result
        for (Document d : myDocs) {
            ArrayList<String> comments = (ArrayList<String>)d.get("comments");
            System.out.println(comments);
        }

        client.close();
    }
}

How can I retrieve a list of values of a field of a document in mongodb using java?

1 Answers1