Question

我需要一些启用QueryDSL的自定义查询方法，并遵循this SO answer。

效果很好，但是升级到Spring Boot 2.1（升级了Spring Data）之后，我发现parseResponse({"Name": "Foo", "Id": 1234, "Rank": 7});已被弃用。只需将其替换为documentation告诉我使用的QuerydslJpaRepository就会导致错误：

由于：java.lang.IllegalArgumentException：类的对象 [... ProjectingQueryDslJpaRepositoryImpl]必须是的实例接口 org.springframework.data.jpa.repository.support.JpaRepositoryImplementation

...但是实现QuerydslJpaPredicateExecutor意味着我必须实现所有标准的CRUD方法，这显然是我所不希望的。因此，如果我从JpaRepositoryImplementation中删除repositoryBaseClass配置，以将其视为带有实现的存储库片段，它将尝试实例化该片段，即使该片段标记有@EnableJpaRepositories，也可以我的错误：

原因：java.lang.IllegalArgumentException：无法创建查询   用于方法public abstract java.util.Optional   ProjectingQueryDslJpaRepository.findOneProjectedBy（com.querydsl.core.types.Expression，com.querydsl.core.types.Predicate）！   提供了至少1个参数，但其中仅存在0个参数   查询。

...

引起者：java.lang.IllegalArgumentException：至少1个参数   提供，但查询中仅提供0个参数。

来源的简要版本：

@NoRepositoryBean

_

@Configuration
@EnableJpaRepositories(basePackageClasses = Application.class, repositoryBaseClass = ProjectingQueryDslJpaRepositoryImpl.class)
@EnableTransactionManagement
@EnableJpaAuditing
@RequiredArgsConstructor(onConstructor = @__({@Autowired}))
public class DatabaseConfig {}

_

@NoRepositoryBean
public interface ProjectingQueryDslJpaRepository<T> extends QuerydslBinderCustomizer<EntityPath<T>>, QuerydslPredicateExecutor<T> {

    @NonNull
    <P> Page<P> findPageProjectedBy(@NonNull Expression<P> factoryExpression, Predicate predicate, 
            @NonNull Pageable pageable);

    @NonNull
    <P> Optional<P> findOneProjectedBy(@NonNull Expression<P> factoryExpression, @NonNull Predicate predicate);

    @Override
    default void customize(@NonNull QuerydslBindings bindings, @NonNull EntityPath<T> root){
        bindings.bind(String.class).first((SingleValueBinding<StringPath, String>) StringExpression::containsIgnoreCase);
    }
}

Answer 1

使用 Spring Boot 2.1.1 ，以下解决方案可能会对您有所帮助。关键是扩展JpaRepositoryFactory并覆盖方法getRepositoryFragments(RepositoryMetadata metadata)。在这种方法中，您可以为任何自定义存储库提供基本（或更具体的片段）实现，每个扩展存储库都应采用这些实现。

让我给你看一个例子：

QueryableReadRepository：

@NoRepositoryBean
public interface QueryableReadRepository<T> extends Repository<T, String> {

  List<T> findAll(Predicate predicate);

  List<T> findAll(Sort sort);

  List<T> findAll(Predicate predicate, Sort sort);

  List<T> findAll(OrderSpecifier<?>... orders);

  List<T> findAll(Predicate predicate, OrderSpecifier<?>... orders);

  Page<T> findAll(Pageable page);

  Page<T> findAll(Predicate predicate, Pageable page);

  Optional<T> findOne(Predicate predicate);

  boolean exists(Predicate predicate);
}

以下界面结合了不同的存储库。

数据存储库：

@NoRepositoryBean
public interface DataRepository<T>
    extends CrudRepository<T, String>, QueryableReadRepository<T> {
}

现在，您的特定域存储库可以从DataRepository扩展：

@Repository
public interface UserRepository extends DataRepository<UserEntity> {

}

QueryableReadRepositoryImpl：

@Transactional
public class QueryableReadRepositoryImpl<T> extends QuerydslJpaPredicateExecutor<T>
    implements QueryableReadRepository<T> {

  private static final EntityPathResolver resolver = SimpleEntityPathResolver.INSTANCE;

  private final EntityPath<T> path;
  private final PathBuilder<T> builder;
  private final Querydsl querydsl;

  public QueryableReadRepositoryImpl(JpaEntityInformation<T, ?> entityInformation,
      EntityManager entityManager) {
    super(entityInformation, entityManager, resolver, null);
    this.path = resolver.createPath(entityInformation.getJavaType());
    this.builder = new PathBuilder<T>(path.getType(), path.getMetadata());
    this.querydsl = new Querydsl(entityManager, builder);
  }

  @Override
  public Optional<T> findOne(Predicate predicate) {
    return super.findOne(predicate);
  }

  @Override
  public List<T> findAll(OrderSpecifier<?>... orders) {
    return super.findAll(orders);
  }

  @Override
  public List<T> findAll(Predicate predicate, Sort sort) {
    return executeSorted(createQuery(predicate).select(path), sort);
  }

  @Override
  public Page<T> findAll(Predicate predicate, Pageable pageable) {
    return super.findAll(predicate, pageable);
  }

  @Override
  public List<T> findAll(Predicate predicate) {
    return super.findAll(predicate);
  }

  public List<T> findAll(Sort sort) {
    return executeSorted(createQuery().select(path), sort);
  }

  @Override
  public Page<T> findAll(Pageable pageable) {
    final JPQLQuery<?> countQuery = createCountQuery();
    JPQLQuery<T> query = querydsl.applyPagination(pageable, createQuery().select(path));

    return PageableExecutionUtils.getPage(
        query.distinct().fetch(), 
        pageable,
        countQuery::fetchCount);
  }

  private List<T> executeSorted(JPQLQuery<T> query, Sort sort) {
    return querydsl.applySorting(sort, query).distinct().fetch();
  }
}

CustomRepositoryFactoryBean ：

public class CustomRepositoryFactoryBean<T extends Repository<S, I>, S, I>
    extends JpaRepositoryFactoryBean<T, S, I> {

  public CustomRepositoryFactoryBean(Class<? extends T> repositoryInterface) {
    super(repositoryInterface);
  }

  protected RepositoryFactorySupport createRepositoryFactory(EntityManager entityManager) {
    return new CustomRepositoryFactory(entityManager);
  }

CustomRepositoryFactory ：

public class CustomRepositoryFactory extends JpaRepositoryFactory {

  private final EntityManager entityManager;

  public CustomRepositoryFactory(EntityManager entityManager) {
    super(entityManager);
    this.entityManager = entityManager;
  }

  @Override
  protected RepositoryFragments getRepositoryFragments(RepositoryMetadata metadata) {
    RepositoryFragments fragments = super.getRepositoryFragments(metadata);

    if (QueryableReadRepository.class.isAssignableFrom(
        metadata.getRepositoryInterface())) {

      JpaEntityInformation<?, Serializable> entityInformation = 
          getEntityInformation(metadata.getDomainType());

      Object queryableFragment = getTargetRepositoryViaReflection(
          QueryableReadRepositoryImpl.class, entityInformation, entityManager);

      fragments = fragments.append(RepositoryFragment.implemented(queryableFragment));
    }

    return fragments;
  }

主类：

@EnableJpaRepositories(repositoryFactoryBeanClass = CustomRepositoryFactoryBean.class)
public class App {
}

这样做的好处是，您只能为自定义存储库提供一个（片段）实现。基本存储库实现仍然是Spring的默认实现。该示例提供了一个新的存储库，但您可能还可以覆盖QuerydslPredicateExecutor

中CustomRepositoryFactory的默认实现。

Answer 2

此测试用例具有使用querydsl运行查询的更干净的版本

https://github.com/spring-projects/spring-data-jpa/blob/master/src/test/java/org/springframework/data/jpa/repository/support/QuerydslJpaPredicateExecutorUnitTests.java

        JpaEntityInformation<User, Integer> information = new JpaMetamodelEntityInformation<>(User.class,
                em.getMetamodel());

        SimpleJpaRepository<User, Integer> repository = new SimpleJpaRepository<>(information, em);
        dave = repository.save(new User("Dave", "Matthews", "dave@matthews.com"));
        carter = repository.save(new User("Carter", "Beauford", "carter@beauford.com"));
        oliver = repository.save(new User("Oliver", "matthews", "oliver@matthews.com"));
        adminRole = em.merge(new Role("admin"));

        this.predicateExecutor = new QuerydslJpaPredicateExecutor<>(information, em, SimpleEntityPathResolver.INSTANCE, null);
        BooleanExpression isCalledDave = user.firstname.eq("Dave");
        BooleanExpression isBeauford = user.lastname.eq("Beauford");

        List<User> result = predicateExecutor.findAll(isCalledDave.or(isBeauford));
        assertThat(result).containsExactlyInAnyOrder(carter, dave);

Answer 3

在Spring Data JPA 2.1.6中，QuerydslJpaPredicateExecutor的构造函数已更改。我在这里提出了一种使用包装https://stackoverflow.com/a/53960209/3351474的替代方法。这使解决方案独立于Spring Data JPA的内部。必须实施3个类。

作为示例，在这里我采用自定义的Querydsl实现，如果不进行任何传递，则始终使用实体的creationDate作为排序标准。在此示例中，我假设所有实体的此列都存在于@MappedSuperClass中。在现实生活中使用生成的静态元数据代替硬编码字符串“ creationDate”。

首先，将所有CustomQuerydslJpaRepositoryIml委派给所有QuerydslJpaPredicateExecutor的包装委派：

/**
 * Customized Querydsl JPA repository to apply custom filtering and sorting logic.
 *
 */
public class CustomQuerydslJpaRepositoryIml<T> implements QuerydslPredicateExecutor<T> {

    private final QuerydslJpaPredicateExecutor querydslPredicateExecutor;

    public CustomQuerydslJpaRepositoryIml(QuerydslJpaPredicateExecutor querydslPredicateExecutor) {
        this.querydslPredicateExecutor = querydslPredicateExecutor;
    }

    private Sort applyDefaultOrder(Sort sort) {
        if (sort.isUnsorted()) {
            return Sort.by("creationDate").ascending();
        }
        return sort;
    }

    private Pageable applyDefaultOrder(Pageable pageable) {
        if (pageable.getSort().isUnsorted()) {
            Sort defaultSort = Sort.by(AuditableEntity_.CREATION_DATE).ascending();
            pageable = PageRequest.of(pageable.getPageNumber(), pageable.getPageSize(), defaultSort);
        }
        return pageable;
    }

    @Override
    public Optional<T> findOne(Predicate predicate) {
        return querydslPredicateExecutor.findOne(predicate);
    }

    @Override
    public List<T> findAll(Predicate predicate) {
        return querydslPredicateExecutor.findAll(predicate);
    }

    @Override
    public List<T> findAll(Predicate predicate, Sort sort) {
        return querydslPredicateExecutor.findAll(predicate, applyDefaultOrder(sort));
    }

    @Override
    public List<T> findAll(Predicate predicate, OrderSpecifier<?>... orders) {
        return querydslPredicateExecutor.findAll(predicate, orders);
    }

    @Override
    public List<T> findAll(OrderSpecifier<?>... orders) {
        return querydslPredicateExecutor.findAll(orders);
    }

    @Override
    public Page<T> findAll(Predicate predicate, Pageable pageable) {
        return querydslPredicateExecutor.findAll(predicate, applyDefaultOrder(pageable));
    }

    @Override
    public long count(Predicate predicate) {
        return querydslPredicateExecutor.count(predicate);
    }

    @Override
    public boolean exists(Predicate predicate) {
        return querydslPredicateExecutor.exists(predicate);
    }
}

接下来，CustomJpaRepositoryFactory发挥作用，并提供Querydsl包装器类，而不是默认的包装器类。默认值作为参数传递并包装。

/**
 * Custom JpaRepositoryFactory allowing to support a custom QuerydslJpaRepository.
 *
 */
public class CustomJpaRepositoryFactory extends JpaRepositoryFactory {

    /**
     * Creates a new {@link JpaRepositoryFactory}.
     *
     * @param entityManager must not be {@literal null}
     */
    public CustomJpaRepositoryFactory(EntityManager entityManager) {
        super(entityManager);
    }

    @Override
    protected RepositoryComposition.RepositoryFragments getRepositoryFragments(RepositoryMetadata metadata) {
        final RepositoryComposition.RepositoryFragments[] modifiedFragments = {RepositoryComposition.RepositoryFragments.empty()};
        RepositoryComposition.RepositoryFragments fragments = super.getRepositoryFragments(metadata);
        // because QuerydslJpaPredicateExecutor is using som internal classes only a wrapper can be used.
        fragments.stream().forEach(
                f -> {
                    if (f.getImplementation().isPresent() &&
                            QuerydslJpaPredicateExecutor.class.isAssignableFrom(f.getImplementation().get().getClass())) {
                        modifiedFragments[0] = modifiedFragments[0].append(RepositoryFragment.implemented(
                                new CustomQuerydslJpaRepositoryIml((QuerydslJpaPredicateExecutor) f.getImplementation().get())));
                    } else {
                        modifiedFragments[0].append(f);
                    }
                }
        );
        return modifiedFragments[0];
    }
}

最后是CustomJpaRepositoryFactoryBean。这必须在Spring Boot应用程序中注册，以使Spring知道从何处获取存储库实现。与：

@SpringBootApplication
@EnableJpaRepositories(basePackages = "your.package",
        repositoryFactoryBeanClass = CustomJpaRepositoryFactoryBean.class)
...

现在是课程：

public class CustomJpaRepositoryFactoryBean<T extends Repository<S, I>, S, I> extends JpaRepositoryFactoryBean<T, S, I> {

    /**
     * Creates a new {@link JpaRepositoryFactoryBean} for the given repository interface.
     *
     * @param repositoryInterface must not be {@literal null}.
     */
    public CustomJpaRepositoryFactoryBean(Class<? extends T> repositoryInterface) {
        super(repositoryInterface);
    }

    protected RepositoryFactorySupport createRepositoryFactory(EntityManager entityManager) {
        return new CustomJpaRepositoryFactory(entityManager);
    }
}

用QuerydslJpaPredicateExecutor替换不推荐使用的QuerydslJpaRepository失败

3 个答案: