Add Custom Method to JPARepository with Generics

问题

Assume I have a Entity called Product. I design a Repo as

@Repository
interface ProductRepository implements JPARepository<Product, Integer>{}

This would inherit all the default methods such as save, findAll etc;

Now I want to have one custom method, which is also a common method for other entities. I added another interface and implementation

interface CustomRepository<T,ID>{ public void customMethod() }
class CustomRepositoryImpl implements CustomRepository<T,ID>{ public void customMethod(){} }

And I rewrite the ProductRepository as

@Repository
interface ProductRepository implements 
JPARepository<Product, Integer>,
CustomRepository<Product, Integer>
{}

Now, this does not give me any compilation error. But during runtime, I get this error:

No property 'customMethod' is found for Product

What am I missing?

回答1:

You seem to be trying to add custom behaviour to a single repository, namely ProductRepository. However, the code is structured as if custom behaviour needs to be added to all repositories (CustomRepository is not specific to Products). Hence, the error.

---

Step 1: Declare a custom repository

interface CustomRepository<T, ID extends Serializable> {
  void customMethod();
}

Step 2: Add custom behaviour to the required repository

interface ProductRepository extends CrudRepository<Product, Integer>
                                    , CustomRepository<Product, Integer> {}

Step 3: Add a Product specific implementation

class ProductRepositoryImpl implements CustomRepository<Product, Integer> { ... }

Note: The class must be named ProductRepositoryImpl for Spring Data JPA plumbing to pick it up automatically.

---

A working example is available on Github.

---

If you would rather add custom behaviour to all repositories, refer to the relevant section in the official documentation.

回答2:

Ok. This is for people who are trying to get this work in a SpringBoot application

follow whatever posted by @manish. Working code here Working Code

You just have to make one small change. Define Model class as

@MappedSuperclass
@IdClass(ModelID.class)
public abstract class Model implements Serializable

define the ID class as

public class ModelID implements Serializable{

    @Column(name = "id")
    @Generated(GenerationTime.INSERT)
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Id

    private Long id;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }



}

This got me working!

来源：https://stackoverflow.com/questions/42337222/add-custom-method-to-jparepository-with-generics