3.3.3 Declaring JPA Repository

When you created the JdbcTemplate versions of the repositories, you explicitly declared the methods you wanted the repository to provide. But with Spring Data JDBC, you were able to dismiss the explicit implementation classes and instead extend the CrudRepository interface. As it turns out, CrudRepository works equally well for Spring Data JPA. For example, here’s the new IngredientRepository interface:

package tacos.data;

import org.springframework.data.repository.CrudRepository;

import tacos.Ingredient;

public interface IngredientRepository
      extends CrudRepository<Ingredient, String> {
}

In fact, the IngredientRepository interface we’ll use with Spring Data JPA is identical to the one we defined for use with Spring Data JDBC. The CrudRepository interface is commonly used across many of Spring Data’s projects, regardless of the underlying persistence mechanism. Similarly, you can define OrderRepository for the Spring Data JPA the same as it was for Spring Data JDBC, as follows:

package tacos.data;

import org.springframework.data.repository.CrudRepository;

import tacos.TacoOrder;

public interface OrderRepository
      extends CrudRepository<TacoOrder, Long> {
}

The methods provided by CrudRepository are great for general-purpose persistence of entities. But what if you have some requirements beyond basic persistence? Let’s see how to customize the repositories to perform queries unique to your domain.