In this source code example, we will demonstrate how to use the delete() method in Spring Data JPA to delete an entity from the database table.

While deleteById() focuses on removing an entity based on its ID, delete() is designed for direct entity removal. If you have an instance of an entity and you wish to remove it from the database, delete() is the method you'd employ.

In this example, we will use the Product entity to save and delete to/from the MySQL database.

Maven Dependencies

First, you need to add the below dependencies to your Spring boot project:

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>

		<dependency>
			<groupId>com.mysql</groupId>
			<artifactId>mysql-connector-j</artifactId>
			<scope>runtime</scope>
		</dependency>

Create Product Entity

Let's first create a Product entity that we are going to save and delete to/from the MySQL database:

package net.javaguides.springdatajpacourse.entity;

import org.hibernate.annotations.CreationTimestamp;
import org.hibernate.annotations.UpdateTimestamp;

import jakarta.persistence.*;
import java.math.BigDecimal;
import java.util.Date;

@Entity
@Table(name="products")
public class Product {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @Column(name = "sku")
    private String sku;

    @Column(name = "name")
    private String name;

    @Column(name = "description")
    private String description;

    @Column(name = "price")
    private BigDecimal price;

    @Column(name = "image_url")
    private String imageUrl;

    @Column(name = "active")
    private boolean active;

    @Column(name = "date_created")
    @CreationTimestamp
    private Date dateCreated;

    @Column(name = "last_updated")
    @UpdateTimestamp
    private Date lastUpdated;

    // getter and setter methods

    @Override
    public String toString() {
        return "Product{" +
                "id=" + id +
                ", sku='" + sku + '\'' +
                ", name='" + name + '\'' +
                ", description='" + description + '\'' +
                ", price=" + price +
                ", imageUrl='" + imageUrl + '\'' +
                ", active=" + active +
                ", dateCreated=" + dateCreated +
                ", lastUpdated=" + lastUpdated +
                '}';
    }
}

ProductRepository

Let's create ProductRepository which extends the JpaRepository interface:

import net.javaguides.springdatajpacourse.entity.Product;
import org.springframework.data.jpa.repository.JpaRepository;

public interface ProductRepository extends JpaRepository<Product, Long> {

}

Configure MySQL and Hibernate Properties

Let's use the MySQL database to store and retrieve the data in this example and we gonna use Hibernate properties to create and drop tables.

Open the application.properties file and add the following configuration to it:

spring.datasource.url=jdbc:mysql://localhost:3306/demo?useSSL=false
spring.datasource.username=root
spring.datasource.password=Mysql@123

spring.jpa.hibernate.ddl-auto = create-drop

spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true

Make sure that you will create a demo database before running the Spring boot application.

Also, change the MySQL username and password as per your MySQL installation on your machine.

Testing delete() Method

Let's write a JUnit test to test delete() method:

import net.javaguides.springdatajpacourse.entity.Product;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureTestDatabase;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.test.annotation.Rollback;

import java.math.BigDecimal;
import java.util.List;

@DataJpaTest
@AutoConfigureTestDatabase(replace= AutoConfigureTestDatabase.Replace.NONE)
class ProductRepositoryTest {

    @Autowired
    private ProductRepository productRepository;

    protected Product getProduct1(){
        Product product = new Product();
        product.setName("product 1");
        product.setDescription("product 1 desc");
        product.setPrice(new BigDecimal(100));
        product.setSku("product 1 sku");
        product.setActive(true);
        product.setImageUrl("product1.png");
        return product;
    }

    @Test
    void testDeleteMethod(){
        Product product = getProduct1();

        productRepository.save(product);

        // delete product by id
        productRepository.delete(product);
    }
}

We are using @DataJpaTest annotation to write a JUnit test for the ProductRepository delete() method.

@AutoConfigureTestDatabase annotation is to disable embedded in-memory database support and enable MySQL database support.

Output

Here is the output of the above JUnit test case we wrote for testing the delete() method:

Hibernate: 
    insert 
    into
        products
        (active, date_created, description, image_url, last_updated, name, price, sku) 
    values
        (?, ?, ?, ?, ?, ?, ?, ?)
Hibernate: 
    delete 
    from
        products 
    where
        id=?

Note that Spring Data JPA (Hibernate) produces the above SQL query to delete a record from the database table.

    delete 
    from
        products 
    where
        id=?

Considerations

Existence Checks: The delete() method will not raise an error if you attempt to delete an entity that doesn't exist in the database. However, if the entity has changes that haven't persisted, you might encounter unexpected results.

Database Constraints: As with deleteById(), ensure the deletion doesn't violate database constraints. Referential integrity issues can arise if related records in other tables depend on the record you're attempting to delete.

Cascading Deletions: JPA's cascading operations mean that deleting a parent entity might cascade the delete operation to its children. Make sure you understand these cascade behaviors when setting up your entity relationships.

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Spring Data JPA delete() Method Example