จะลบเอกสารหลายชุดออกจากคอลเล็กชันโดยใช้ Java ได้อย่างไร

ใน Java com.mongodb.client.MongoCollection อินเทอร์เฟซให้วิธีการ deleteMany() . เมื่อใช้วิธีนี้ คุณจะลบเอกสารหลายชุดออกจากชุดข้อมูลได้ในคราวเดียว สำหรับวิธีนี้ คุณจะต้องผ่านตัวกรองที่ระบุเกณฑ์การลบ

ตัวอย่าง

import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.bson.Document;
import org.bson.conversions.Bson;
import com.mongodb.MongoClient;
public class DeletingMultipleDocuments {
   public static void main( String args[] ) {
      //Creating a MongoDB client
      MongoClient mongo = new MongoClient( "localhost" , 27017 );
      //Connecting to the database
      MongoDatabase database = mongo.getDatabase("myDatabase");
      //Creating a collection object
      MongoCollection<Document>collection = database.getCollection("students");
      Document document1 = new Document("name", "Ram").append("age", 26).append("city", "Delhi");
      Document document2 = new Document("name", "Robert").append("age", 27).append("city", "Vishakhapatnam");
      Document document3 = new Document("name", "Rhim").append("age", 30).append("city", "Delhi");
      Document document4 = new Document("name", "Radha").append("age", 45).append("city", "Delhi");
      Document document5 = new Document("name", "Sarmista").append("age", 35).append("city", "Mumbai");
      //Inserting the created documents
      List<Document> list = new ArrayList<Document>();
      list.add(document1);
      list.add(document2);
      list.add(document3);
      list.add(document4);
      list.add(document5);
      collection.insertMany(list);
      System.out.println("Documents Inserted");
      System.out.println("Contents of the collection:");
      FindIterable<Document> iterDoc = collection.find();
      int i = 1;
      System.out.println("Remaining documents:");
      Iterator it = iterDoc.iterator();
      while (it.hasNext()) {
         System.out.println(it.next());
         i++;
      }
      collection = database.getCollection("students");
      //Deleting multiple documents
      Bson filter = new Document("city", "Delhi");
      collection.deleteMany(filter);
      System.out.println("Document deleted successfully...");
      //Retrieving the documents after the delete operation
      iterDoc = collection.find();
      System.out.println("Remaining documents:");
      it = iterDoc.iterator();
      while (it.hasNext()) {
         System.out.println(it.next());
         i++;
      }
   }
}

ผลลัพธ์

Documents Inserted
Contents of the collection:
Remaining documents:
Document{{_id=5e896b042e4a2f3badebddae, name=Ram, age=26, city=Delhi}}
Document{{_id=5e896b042e4a2f3badebddaf, name=Robert, age=27, city=Vishakhapatnam}}
Document{{_id=5e896b042e4a2f3badebddb0, name=Rhim, age=30, city=Delhi}}
Document{{_id=5e896b042e4a2f3badebddb1, name=Radha, age=45, city=Delhi}}
Document{{_id=5e896b042e4a2f3badebddb2, name=Sarmista, age=35, city=Mumbai}}
Document deleted successfully...
Remaining documents:
Document{{_id=5e896b042e4a2f3badebddaf, name=Robert, age=27, city=Vishakhapatnam}}
Document{{_id=5e896b042e4a2f3badebddb2, name=Sarmista, age=35, city=Mumbai}}