/
CustomerRepository.java
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/
CustomerRepository.java
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/*
* Copyright 2015-2021 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package example.springdata.jpa.projections;
import java.util.Collection;
import java.util.Optional;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.CrudRepository;
/**
* @author Oliver Gierke
*/
public interface CustomerRepository extends CrudRepository<Customer, Long> {
/**
* Uses a projection interface to indicate the fields to be returned. As the projection doesn't use any dynamic
* fields, the query execution will be restricted to only the fields needed by the projection.
*
* @return
*/
Collection<CustomerProjection> findAllProjectedBy();
/**
* When a projection is used that contains dynamic properties (i.e. SpEL expressions in an {@link Value} annotation),
* the normal target entity will be loaded but dynamically projected so that the target can be referred to in the
* expression.
*
* @return
*/
Collection<CustomerSummary> findAllSummarizedBy();
/**
* Projection interfaces can be used with manually declared queries, too. Make sure you alias the projects matching
* the projection fields.
*
* @return
*/
@Query("select c.firstname as firstname, c.lastname as lastname from Customer c")
Collection<CustomerProjection> findsByProjectedColumns();
/**
* Uses a concrete DTO type to indicate the fields to be returned. This gets translated into a constructor expression
* in the query.
*
* @return
*/
Collection<CustomerDto> findAllDtoedBy();
/**
* Passes in the projection type dynamically (either interface or DTO).
*
* @param firstname
* @param projection
* @return
*/
<T> Collection<T> findByFirstname(String firstname, Class<T> projection);
/**
* Projection for a single entity.
*
* @param id
* @return
*/
CustomerProjection findProjectedById(Long id);
/**
* Dynamic projection for a single entity.
*
* @param id
* @param projection
* @return
*/
<T> T findProjectedById(Long id, Class<T> projection);
/**
* Projections used with pagination.
*
* @param pageable
* @return
*/
Page<CustomerProjection> findPagedProjectedBy(Pageable pageable);
/**
* A DTO projection using a constructor expression in a manually declared query.
*
* @param firstname
* @return
*/
@Query("select new example.springdata.jpa.projections.CustomerDto(c.firstname) from Customer c where c.firstname = ?1")
Collection<CustomerDto> findDtoWithConstructorExpression(String firstname);
/**
* A projection wrapped into an {@link Optional}.
*
* @param lastname
* @return
*/
Optional<CustomerProjection> findOptionalProjectionByLastname(String lastname);
}