Spring Data Annotations

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Introduction

Spring Data provides an abstraction over data storage technologies.

Common Spring Data Annotations

@Transactional

@NoRepositoryBean

@Param

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@Query("FROM Person p WHERE p.name = :name")
Person findByName(@Param("name") String name);

@Id

@Id marks a field in a model class as the primary key

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class Person {

    @Id
    Long id;
}

@Transient

We can use this annotation to mark a field in a model class as transient. Hence the data store engine won’t read or write this field’s value

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class Person {

    @Transient
    int age;
}

@CreatedBy, @LastModifiedBy, @CreatedDate, @LastModifiedDate

With these annotations, we can audit our model classes: Spring automatically populates the annotated fields with the principal who created the object, last modified it, and the date of creation, and last modification:

Note, that if we want Spring to populate the principals, we need to use Spring Security as well.

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public class Person {

    @CreatedBy
    User creator;

    @LastModifiedBy
    User modifier;

    @CreatedDate
    Date createdAt;

    @LastModifiedDate
    Date modifiedAt;

    // ...

}

Spring Data JPA Annotations

@Query

@Procedure

@Lock

We can configure the lock mode when we execute a repository query method

• READ
• WRITE
• OPTIMISTIC
• OPTIMISTIC_FORCE_INCREMENT
• PESSIMISTIC_READ
• PESSIMISTIC_WRITE
• PESSIMISTIC_FORCE_INCREMENT
• NONE

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@Lock(LockModeType.NONE)
@Query("SELECT COUNT(*) FROM Person p")
long getPersonCount();

@Modifying

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@Modifying
@Query("UPDATE Person p SET p.name = :name WHERE p.id = :id")
void changeName(@Param("id") long id, @Param("name") String name);

@EnableJpaRepositories

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@Configuration
@EnableJpaRepositories(basePackages = "org.baeldung.persistence.dao")
class PersistenceJPAConfig {}