MongoDB Java Integration Guide: Deleting Documents from MongoDB Collections in Java

This blog will teach you how to delete one or more documents from a MongoDB collection using Java. You will learn how to use the deleteOne and deleteMany methods, the Filters class, and the DeleteResult object.

Table of Contents

1. Introduction

MongoDB is a popular open-source document-oriented database that stores data in JSON-like format. It offers high performance, scalability, and flexibility for various applications. One of the common operations that you may need to perform on a MongoDB database is deleting documents from a collection.

In this tutorial, you will learn how to delete one or more documents from a MongoDB collection using Java. You will use the MongoDB Java driver, which is the official Java client library for MongoDB. You will also learn how to use the deleteOne and deleteMany methods, the Filters class, and the DeleteResult object to perform and handle the deletion operation.

By the end of this tutorial, you will be able to delete documents from a MongoDB collection using Java with ease and confidence. You will also gain a better understanding of how MongoDB works with Java and how to use its features effectively.

Are you ready to get started? Let’s begin!

2. Setting Up the MongoDB Java Driver

The first step to delete documents from a MongoDB collection using Java is to set up the MongoDB Java driver. The MongoDB Java driver is the official Java client library for MongoDB that allows you to interact with the database from your Java application. You can use the driver to perform various operations on MongoDB, such as creating, reading, updating, and deleting documents.

To set up the MongoDB Java driver, you need to add it as a dependency to your project. There are different ways to do this, depending on the build tool that you are using. For example, if you are using Maven, you can add the following dependency to your pom.xml file:

<dependency>
    <groupId>org.mongodb</groupId>
    <artifactId>mongodb-driver-sync</artifactId>
    <version>4.3.3</version>
</dependency>

If you are using Gradle, you can add the following dependency to your build.gradle file:

dependencies {
    implementation 'org.mongodb:mongodb-driver-sync:4.3.3'
}

You can also download the driver JAR file from the Maven repository and add it to your project classpath manually.

Once you have added the MongoDB Java driver as a dependency, you can import it in your Java code and use its classes and methods to connect to and interact with MongoDB. In the next section, you will learn how to connect to a MongoDB database and collection using Java.

3. Connecting to a MongoDB Database and Collection

After setting up the MongoDB Java driver, the next step is to connect to a MongoDB database and collection. A MongoDB database is a container for collections, which are groups of documents that share a common schema. A MongoDB document is a JSON-like object that stores data as key-value pairs.

To connect to a MongoDB database and collection, you need to create a MongoClient object, which represents a connection pool to the database server. You can use the MongoClients class to create a MongoClient object with the default settings or with a custom connection string. For example, the following code creates a MongoClient object with the default settings, which connects to the local host on port 27017:

MongoClient mongoClient = MongoClients.create();

If you want to connect to a remote MongoDB server or specify other connection options, you can use a connection string that follows the MongoDB connection string URI format. For example, the following code creates a MongoClient object with a connection string that connects to a MongoDB server on a different host and port:

MongoClient mongoClient = MongoClients.create("mongodb://example.com:27018");

Once you have a MongoClient object, you can use it to get a reference to a MongoDatabase object, which represents a MongoDB database. You can use the getDatabase method of the MongoClient object and pass the name of the database as a parameter. For example, the following code gets a reference to a database named test:

MongoDatabase database = mongoClient.getDatabase("test");

Similarly, you can use the getCollection method of the MongoDatabase object to get a reference to a MongoCollection object, which represents a MongoDB collection. You can pass the name of the collection as a parameter. For example, the following code gets a reference to a collection named users:

MongoCollection collection = database.getCollection("users");

Now you have a MongoCollection object that you can use to perform various operations on the collection, such as deleting documents. In the next section, you will learn how to delete a single document from a MongoDB collection using Java.

4. Deleting a Single Document from a MongoDB Collection

In this section, you will learn how to delete a single document from a MongoDB collection using Java. You will use the deleteOne method of the MongoCollection object, which takes a filter as a parameter and deletes the first document that matches the filter. You will also use the Filters class, which provides static methods to create filters for various conditions. Finally, you will use the DeleteResult object, which represents the result of the deletion operation and provides information such as the number of deleted documents.

To delete a single document from a MongoDB collection using Java, you need to follow these steps:

Create a filter that specifies the condition for the document to be deleted. You can use the Filters class to create filters based on different criteria, such as equality, comparison, logical, array, and text. For example, the following code creates a filter that matches documents where the name field is equal to “Alice”:

Bson filter = Filters.eq("name", "Alice");

Call the deleteOne method of the MongoCollection object and pass the filter as a parameter. The method returns a DeleteResult object that contains information about the deletion operation. For example, the following code deletes the first document that matches the filter from the users collection and stores the result in a variable named result:

DeleteResult result = collection.deleteOne(filter);

Use the DeleteResult object to get information about the deletion operation, such as the number of deleted documents, the write concern, and the server address. You can use the getDeletedCount method to get the number of deleted documents, which should be either 0 or 1. For example, the following code prints the number of deleted documents to the console:

System.out.println("Number of deleted documents: " + result.getDeletedCount());

That’s it! You have successfully deleted a single document from a MongoDB collection using Java. You can use the same steps to delete any document that matches a given filter from any collection. However, if you want to delete more than one document at a time, you need to use a different method. In the next section, you will learn how to delete multiple documents from a MongoDB collection using Java.

4.1. Using the deleteOne Method

The deleteOne method of the MongoCollection object allows you to delete a single document from a MongoDB collection that matches a given filter. The filter is a Bson object that specifies the condition for the document to be deleted. The Bson interface represents a type-safe way to create and manipulate BSON documents, which are the binary representation of JSON documents used by MongoDB.

To use the deleteOne method, you need to pass a Bson object as a parameter. You can create a Bson object using the Filters class, which provides static methods to create filters based on different criteria, such as equality, comparison, logical, array, and text. For example, the following code creates a Bson object that matches documents where the age field is greater than 30:

Bson filter = Filters.gt("age", 30);

Then, you can call the deleteOne method of the MongoCollection object and pass the Bson object as a parameter. The method returns a DeleteResult object that contains information about the deletion operation, such as the number of deleted documents, the write concern, and the server address. For example, the following code deletes the first document that matches the filter from the users collection and stores the result in a variable named result:

DeleteResult result = collection.deleteOne(filter);

You can use the DeleteResult object to get information about the deletion operation, such as the number of deleted documents, which should be either 0 or 1. You can use the getDeletedCount method to get the number of deleted documents. For example, the following code prints the number of deleted documents to the console:

System.out.println("Number of deleted documents: " + result.getDeletedCount());

In this section, you learned how to use the deleteOne method to delete a single document from a MongoDB collection using Java. You also learned how to use the Filters class to create a Bson object that specifies the condition for the document to be deleted. In the next section, you will learn how to use the Filters class to create more complex filters for deleting documents.

4.2. Using the Filters Class

The Filters class is a utility class that provides static methods to create Bson objects that represent filters for various conditions. You can use the Filters class to create filters based on different criteria, such as equality, comparison, logical, array, and text. You can also combine multiple filters using the and and or methods of the Filters class.

Some of the common methods of the Filters class are:

eq: Creates a filter that matches documents where the value of a field is equal to a specified value.
gt: Creates a filter that matches documents where the value of a field is greater than a specified value.
gte: Creates a filter that matches documents where the value of a field is greater than or equal to a specified value.
lt: Creates a filter that matches documents where the value of a field is less than a specified value.
lte: Creates a filter that matches documents where the value of a field is less than or equal to a specified value.
ne: Creates a filter that matches documents where the value of a field is not equal to a specified value.
in: Creates a filter that matches documents where the value of a field is in a specified list of values.
nin: Creates a filter that matches documents where the value of a field is not in a specified list of values.
and: Creates a filter that matches documents where all the specified filters are true.
or: Creates a filter that matches documents where any of the specified filters are true.
not: Creates a filter that matches documents where the specified filter is false.
exists: Creates a filter that matches documents where a field exists or does not exist.
type: Creates a filter that matches documents where the type of a field is a specified BSON type.
regex: Creates a filter that matches documents where the value of a field matches a specified regular expression.
text: Creates a filter that performs a text search on a text index.
elemMatch: Creates a filter that matches documents where an array field contains an element that matches the specified filter.
size: Creates a filter that matches documents where an array field has the specified number of elements.
all: Creates a filter that matches documents where an array field contains all the specified values.

For example, the following code creates a filter that matches documents where the name field is equal to “Bob” and the age field is greater than 25:

Bson filter = Filters.and(Filters.eq("name", "Bob"), Filters.gt("age", 25));

You can use the Filters class to create complex filters for deleting documents from a MongoDB collection using Java. In the next section, you will learn how to handle the DeleteResult object that represents the result of the deletion operation.

4.3. Handling the DeleteResult Object

The DeleteResult object is a class that represents the result of a deletion operation on a MongoDB collection. It provides information such as the number of deleted documents, the write concern, and the server address. You can use the DeleteResult object to verify and handle the outcome of the deletion operation.

Some of the common methods of the DeleteResult object are:

getDeletedCount: Returns the number of deleted documents as a long value. It should be either 0 or 1 for the deleteOne method, or any positive number for the deleteMany method.
wasAcknowledged: Returns a boolean value that indicates whether the deletion operation was acknowledged by the server. It depends on the write concern that was used for the operation.
getServerAddress: Returns a ServerAddress object that represents the address of the server that performed the deletion operation.

For example, the following code prints the number of deleted documents, the acknowledgement status, and the server address to the console:

System.out.println("Number of deleted documents: " + result.getDeletedCount());
System.out.println("Acknowledgement status: " + result.wasAcknowledged());
System.out.println("Server address: " + result.getServerAddress());

You can use the DeleteResult object to check and handle the result of the deletion operation, such as logging the information, throwing an exception, or performing some other action. In the next section, you will learn how to delete multiple documents from a MongoDB collection using Java.

5. Deleting Multiple Documents from a MongoDB Collection

In this section, you will learn how to delete multiple documents from a MongoDB collection using Java. You will use the deleteMany method of the MongoCollection object, which takes a filter as a parameter and deletes all the documents that match the filter. You will also use the Filters class, which provides static methods to create filters for various conditions. Finally, you will use the DeleteResult object, which represents the result of the deletion operation and provides information such as the number of deleted documents.

To delete multiple documents from a MongoDB collection using Java, you need to follow these steps:

Create a filter that specifies the condition for the documents to be deleted. You can use the Filters class to create filters based on different criteria, such as equality, comparison, logical, array, and text. For example, the following code creates a filter that matches documents where the status field is equal to “inactive”:

Bson filter = Filters.eq("status", "inactive");

Call the deleteMany method of the MongoCollection object and pass the filter as a parameter. The method returns a DeleteResult object that contains information about the deletion operation. For example, the following code deletes all the documents that match the filter from the users collection and stores the result in a variable named result:

DeleteResult result = collection.deleteMany(filter);

Use the DeleteResult object to get information about the deletion operation, such as the number of deleted documents, which should be a positive number. You can use the getDeletedCount method to get the number of deleted documents. For example, the following code prints the number of deleted documents to the console:

System.out.println("Number of deleted documents: " + result.getDeletedCount());

That’s it! You have successfully deleted multiple documents from a MongoDB collection using Java. You can use the same steps to delete any number of documents that match a given filter from any collection. However, if you want to delete all the documents from a collection, you need to use a different method. In the next section, you will learn how to delete all the documents from a MongoDB collection using Java.

5.1. Using the deleteMany Method

The deleteMany method of the MongoCollection object allows you to delete multiple documents from a MongoDB collection that match a given filter. The filter is a Bson object that specifies the condition for the documents to be deleted. The Bson interface represents a type-safe way to create and manipulate BSON documents, which are the binary representation of JSON documents used by MongoDB.

To use the deleteMany method, you need to pass a Bson object as a parameter. You can create a Bson object using the Filters class, which provides static methods to create filters based on different criteria, such as equality, comparison, logical, array, and text. For example, the following code creates a Bson object that matches documents where the status field is equal to “inactive”:

Bson filter = Filters.eq("status", "inactive");

Then, you can call the deleteMany method of the MongoCollection object and pass the Bson object as a parameter. The method returns a DeleteResult object that contains information about the deletion operation, such as the number of deleted documents, the write concern, and the server address. For example, the following code deletes all the documents that match the filter from the users collection and stores the result in a variable named result:

DeleteResult result = collection.deleteMany(filter);

You can use the DeleteResult object to get information about the deletion operation, such as the number of deleted documents, which should be a positive number. You can use the getDeletedCount method to get the number of deleted documents. For example, the following code prints the number of deleted documents to the console:

System.out.println("Number of deleted documents: " + result.getDeletedCount());

5.2. Using the Filters Class

Some of the common methods of the Filters class are:

eq: Creates a filter that matches documents where the value of a field is equal to a specified value.
gt: Creates a filter that matches documents where the value of a field is greater than a specified value.
gte: Creates a filter that matches documents where the value of a field is greater than or equal to a specified value.
lt: Creates a filter that matches documents where the value of a field is less than a specified value.
lte: Creates a filter that matches documents where the value of a field is less than or equal to a specified value.
ne: Creates a filter that matches documents where the value of a field is not equal to a specified value.
in: Creates a filter that matches documents where the value of a field is in a specified list of values.
nin: Creates a filter that matches documents where the value of a field is not in a specified list of values.
and: Creates a filter that matches documents where all the specified filters are true.
or: Creates a filter that matches documents where any of the specified filters are true.
not: Creates a filter that matches documents where the specified filter is false.
exists: Creates a filter that matches documents where a field exists or does not exist.
type: Creates a filter that matches documents where the type of a field is a specified BSON type.
regex: Creates a filter that matches documents where the value of a field matches a specified regular expression.
text: Creates a filter that performs a text search on a text index.
elemMatch: Creates a filter that matches documents where an array field contains an element that matches the specified filter.
size: Creates a filter that matches documents where an array field has the specified number of elements.
all: Creates a filter that matches documents where an array field contains all the specified values.

For example, the following code creates a filter that matches documents where the name field is equal to “Bob” and the age field is greater than 25:

Bson filter = Filters.and(Filters.eq("name", "Bob"), Filters.gt("age", 25));

5.3. Handling the DeleteResult Object

Some of the common methods of the DeleteResult object are:

getDeletedCount: Returns the number of deleted documents as a long value. It should be either 0 or 1 for the deleteOne method, or any positive number for the deleteMany method.
wasAcknowledged: Returns a boolean value that indicates whether the deletion operation was acknowledged by the server. It depends on the write concern that was used for the operation.
getServerAddress: Returns a ServerAddress object that represents the address of the server that performed the deletion operation.

For example, the following code prints the number of deleted documents, the acknowledgement status, and the server address to the console:

System.out.println("Number of deleted documents: " + result.getDeletedCount());
System.out.println("Acknowledgement status: " + result.wasAcknowledged());
System.out.println("Server address: " + result.getServerAddress());

You can use the DeleteResult object to check and handle the result of the deletion operation, such as logging the information, throwing an exception, or performing some other action. In the next section, you will learn how to delete all the documents from a MongoDB collection using Java.

6. Conclusion

In this tutorial, you have learned how to delete documents from a MongoDB collection using Java. You have used the MongoDB Java driver, which is the official Java client library for MongoDB, to connect to and interact with the database. You have also used the deleteOne and deleteMany methods of the MongoCollection object, the Filters class, and the DeleteResult object to perform and handle the deletion operation.

By following this tutorial, you have gained a better understanding of how MongoDB works with Java and how to use its features effectively. You have also learned how to delete one or more documents from a MongoDB collection using Java with ease and confidence.

We hope you enjoyed this tutorial and found it useful. If you have any questions or feedback, please feel free to leave a comment below. Thank you for reading and happy coding!