[java] What is difference between CrudRepository and JpaRepository interfaces in Spring Data JPA?

What is the difference between CrudRepository and JpaRepository interfaces in Spring Data JPA?

When I see the examples on the web, I see them there used kind of interchangeably.

What is the difference between them?

Why would you want to use one over the other?

All the answers provide sufficient details to the question. However, let me add something more.

Why are we using these Interfaces:

• They allow Spring to find your repository interfaces and create proxy objects for them.
• It provides you with methods that allow you to perform some common operations (you can also define your custom method as well). I love this feature because creating a method (and defining query and prepared statements and then execute the query with connection object) to do a simple operation really sucks !

Which interface does what:

• CrudRepository: provides CRUD functions
• PagingAndSortingRepository: provides methods to do pagination and sort records
• JpaRepository: provides JPA related methods such as flushing the persistence context and delete records in a batch

When to use which interface:

According to http://jtuts.com/2014/08/26/difference-between-crudrepository-and-jparepository-in-spring-data-jpa/

Generally the best idea is to use CrudRepository or PagingAndSortingRepository depending on whether you need sorting and paging or not.

The JpaRepository should be avoided if possible, because it ties you repositories to the JPA persistence technology, and in most cases you probably wouldn’t even use the extra methods provided by it.

Summary:

• PagingAndSortingRepository extends CrudRepository

• JpaRepository extends PagingAndSortingRepository

The CrudRepository interface provides methods for CRUD operations, so it allows you to create, read, update and delete records without having to define your own methods.

The PagingAndSortingRepository provides additional methods to retrieve entities using pagination and sorting.

Finally the JpaRepository add some more functionality that is specific to JPA.

Ken's answer is basically right but I'd like to chime in on the "why would you want to use one over the other?" part of your question.

Basics

The base interface you choose for your repository has two main purposes. First, you allow the Spring Data repository infrastructure to find your interface and trigger the proxy creation so that you inject instances of the interface into clients. The second purpose is to pull in as much functionality as needed into the interface without having to declare extra methods.

The common interfaces

The Spring Data core library ships with two base interfaces that expose a dedicated set of functionalities:

• CrudRepository - CRUD methods
• PagingAndSortingRepository - methods for pagination and sorting (extends CrudRepository)

Store-specific interfaces

The individual store modules (e.g. for JPA or MongoDB) expose store-specific extensions of these base interfaces to allow access to store-specific functionality like flushing or dedicated batching that take some store specifics into account. An example for this is deleteInBatch(…) of JpaRepository which is different from delete(…) as it uses a query to delete the given entities which is more performant but comes with the side effect of not triggering the JPA-defined cascades (as the spec defines it).

We generally recommend not to use these base interfaces as they expose the underlying persistence technology to the clients and thus tighten the coupling between them and the repository. Plus, you get a bit away from the original definition of a repository which is basically "a collection of entities". So if you can, stay with PagingAndSortingRepository.

Custom repository base interfaces

The downside of directly depending on one of the provided base interfaces is two-fold. Both of them might be considered as theoretical but I think they're important to be aware of:

1. Depending on a Spring Data repository interface couples your repository interface to the library. I don't think this is a particular issue as you'll probably use abstractions like Page or Pageable in your code anyway. Spring Data is not any different from any other general purpose library like commons-lang or Guava. As long as it provides reasonable benefit, it's just fine.
2. By extending e.g. CrudRepository, you expose a complete set of persistence method at once. This is probably fine in most circumstances as well but you might run into situations where you'd like to gain more fine-grained control over the methods expose, e.g. to create a ReadOnlyRepository that doesn't include the save(…) and delete(…) methods of CrudRepository.

The solution to both of these downsides is to craft your own base repository interface or even a set of them. In a lot of applications I have seen something like this:

interface ApplicationRepository<T> extends PagingAndSortingRepository<T, Long> { }

interface ReadOnlyRepository<T> extends Repository<T, Long> {

  // Al finder methods go here
}

The first repository interface is some general purpose base interface that actually only fixes point 1 but also ties the ID type to be Long for consistency. The second interface usually has all the find…(…) methods copied from CrudRepository and PagingAndSortingRepository but does not expose the manipulating ones. Read more on that approach in the reference documentation.

Summary - tl;dr

The repository abstraction allows you to pick the base repository totally driven by you architectural and functional needs. Use the ones provided out of the box if they suit, craft your own repository base interfaces if necessary. Stay away from the store specific repository interfaces unless unavoidable.

Below are the differences between CrudRepository and JpaRepository as:

CrudRepository

1. CrudRepository is a base interface and extends the Repository interface.
2. CrudRepository mainly provides CRUD (Create, Read, Update, Delete) operations.
3. Return type of saveAll() method is Iterable.
4. Use Case - To perform CRUD operations, define repository extending CrudRepository.

JpaRepository

1. JpaRepository extends PagingAndSortingRepository that extends CrudRepository.
2. JpaRepository provides CRUD and pagination operations, along with additional methods like flush(), saveAndFlush(), and deleteInBatch(), etc.
3. Return type of saveAll() method is a List.
4. Use Case - To perform CRUD as well as batch operations, define repository extends JpaRepository.

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