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Java & MongoDB - Select Document
  • 时间:2024-12-22

Java & MongoDB - Select Document


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To select a document in a collection, you can use collection.find() or collection.find(filter) methods to select documents of a collection.


// find all documents of a collection
collection.find();

// find document(s) fulfipng the filter criteria
collection.find(filter);

Example

Following is the code snippet to display selected documents −


import java.util.ArrayList;
import java.util.List;

import org.bson.Document;

import com.mongodb.cpent.FindIterable;
import com.mongodb.cpent.MongoCpent;
import com.mongodb.cpent.MongoCpents;
import com.mongodb.cpent.MongoCollection;
import com.mongodb.cpent.MongoDatabase;
import com.mongodb.cpent.model.Filters;

pubpc class Tester {
   pubpc static void main(String[] args) {
      // Creating a Mongo cpent 
      MongoCpent mongoCpent = MongoCpents.create("mongodb://localhost:27017");
      MongoDatabase database = mongoCpent.getDatabase("myDb");

      // Get the collection
      MongoCollection<Document> collection = database.getCollection("sampleCollection");

      // Find all documents
      FindIterable<Document> allDocuments = collection.find();

      for (Document document : allDocuments) {
         System.out.println(document);
      }
      System.out.println("***Selected Document***");
      
      // Select a particular document
      FindIterable<Document> documents = collection.find(Filters.eq("First_Name","Mahesh"));
      for (Document document : documents) {
         System.out.println(document);
      }
   }
}

Now, let s compile and run the above program as shown below.


$javac Tester.java 
$java Tester

Output

On executing, the above program gives you the following output.


Document{{_id=60b70d426214461f10ac5c99, First_Name=Mahesh, Last_Name=Parashar, Date_Of_Birth=1990-08-21, e_mail=mahesh_parashar.123@gmail.com, phone=9034343345}}
Document{{_id=60b70d426214461f10ac5c9a, First_Name=Radhika, Last_Name=Sharma, Date_Of_Birth=1995-09-26, e_mail=radhika_sharma.123@gmail.com, phone=9000012345}}
Document{{_id=60b70d426214461f10ac5c9b, First_Name=Rachel, Last_Name=Christopher, Date_Of_Birth=1990-02-16, e_mail=Rachel_Christopher.123@gmail.com, phone=9000054321}}
Document{{_id=60b70d426214461f10ac5c9c, First_Name=Fathima, Last_Name=Sheik, Date_Of_Birth=1990-02-16, e_mail=Fathima_Sheik.123@gmail.com, phone=9000054321}}
********
Document{{_id=60b70d426214461f10ac5c99, First_Name=Mahesh, Last_Name=Parashar, Date_Of_Birth=1990-08-21, e_mail=mahesh_parashar.123@gmail.com, phone=9034343345}}
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