在QueryDSL中按可空子对象的属性对模型对象进行排序

时间：2017-03-02 03:34:37

标签： spring spring-boot spring-data-jpa querydsl

我的要求是检索所有图像（WAHImage）对象，无论样本（SpecimenImpl）是否为空，分类单元名称（WACensusImpl）是否为空，并按样本名称或分类单元名称排序结果（如果有） ，首先显示带有空样本和空分类名称的图像对象。

使用下面的代码，我收到错误No property coalesce(wAHimage found for type WAHImage。

很明显，我的用例是not (yet) fully supported in QueryDSL，即查询实体并按其可空子对象的属性对结果对象进行排序的能力。这是因为QueryDSL使用CROSS JOIN而不是LEFT JOIN，并且您不能通过CROSS JOIN按子对象属性进行排序。这似乎是我沮丧的根源，我现在正在寻找其他解决方案，而不是坚持使用QueryDSL。

Spring Data JPA存储库：

public interface ImageRepository extends JpaRepository<WAHImage, Long>,
        QueryDslPredicateExecutor<WAHImage> {
    Page<WAHImage> findAllByIsDeleted(boolean isDeleted, Pageable page);
}

Spring Boot（1.5.1）服务，在其构造函数中自动装配ImageRepository：

@Service
public class ImageService {
    private ImageRepository imageRepository;
    public Page<WAHImage> get(Pageable pageable) {
        return imageRepository.findAllByIsDeleted(false, ImagePredicates.orderByName(pageable));
    }

ImagePredicates.orderByName（可分页）：

static QPageRequest orderByName(Pageable page) {

    QWAHImage image = QWAHImage.wAHImage;
    QWACensusImpl name = image.census;
    QSpecimenImpl specimen = image.specimen;
    OrderSpecifier genus = name.name1.coalesce(specimen.genus).asc();
    OrderSpecifier species = name.name2.coalesce(specimen.species).asc();
    OrderSpecifier rank = name.rank4.coalesce(
            name.rank3.coalesce(specimen.rank)).asc();
    OrderSpecifier infraspecies = name.name4.coalesce(
            name.name3.coalesce(specimen.infraspecies)).asc();

    OrderSpecifier[] sort = new OrderSpecifier[] {
            genus, species, rank, infraspecies
    };

    return new QPageRequest(page.getPageNumber(), page.getPageSize(), sort);
}

控制器：

@Controller
public class ImageController {
    @GetMapping("/list")
    public String list(Pageable pageable, Model model) {
        Page<WAHImage> searchResult = imageService.get(pageable);
    }
}

错误：

org.springframework.data.mapping.PropertyReferenceException: No property coalesce(wAHImage found for type WAHImage!
at org.springframework.data.mapping.PropertyPath.<init>(PropertyPath.java:77)
at org.springframework.data.mapping.PropertyPath.create(PropertyPath.java:329)
at org.springframework.data.mapping.PropertyPath.create(PropertyPath.java:309)
at org.springframework.data.mapping.PropertyPath.from(PropertyPath.java:272)
at org.springframework.data.mapping.PropertyPath.from(PropertyPath.java:243)
at org.springframework.data.jpa.repository.query.QueryUtils.toJpaOrder(QueryUtils.java:542)
at org.springframework.data.jpa.repository.query.QueryUtils.toOrders(QueryUtils.java:496)
at org.springframework.data.jpa.repository.query.JpaQueryCreator.complete(JpaQueryCreator.java:195)
at org.springframework.data.jpa.repository.query.JpaQueryCreator.complete(JpaQueryCreator.java:143)
at org.springframework.data.jpa.repository.query.JpaQueryCreator.complete(JpaQueryCreator.java:52)
at org.springframework.data.repository.query.parser.AbstractQueryCreator.createQuery(AbstractQueryCreator.java:88)
at org.springframework.data.jpa.repository.query.PartTreeJpaQuery$QueryPreparer.createQuery(PartTreeJpaQuery.java:144)
at org.springframework.data.jpa.repository.query.PartTreeJpaQuery.doCreateQuery(PartTreeJpaQuery.java:79)
at org.springframework.data.jpa.repository.query.AbstractJpaQuery.createQuery(AbstractJpaQuery.java:190)
at org.springframework.data.jpa.repository.query.JpaQueryExecution$PagedExecution.doExecute(JpaQueryExecution.java:184)
at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:85)
at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:116)
at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:106)
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:483)
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:461)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:61)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:133)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:57)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
at com.sun.proxy.$Proxy143.findAllByIsDeleted(Unknown Source)
at x.y.z.image.ImageService.get(ImageService.java:120)
at x.y.z.image.ImageService$$FastClassBySpringCGLIB$$6d3a7999.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:652)
at x.y.z.image.ImageService$$EnhancerBySpringCGLIB$$21037cfe.get(<generated>)
at x.y.z.controller.image.ImageController.list(ImageController.java:132)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)

WAHImage模型类的相关部分。

@Entity
@Table(name = "image")
public class WAHImage extends PersistentImpl {
    private WACensusImpl census = new WACensusImpl();
    private SpecimenImpl specimen = new SpecimenImpl();
    private boolean isDeleted = Boolean.FALSE;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "census_id", nullable = true)
    public WACensusImpl getCensus() {
        return census;
    }

    public void setCensus(WACensusImpl census) {
        this.census = census;
    }

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "specimen_id", nullable = true)
    public SpecimenImpl getSpecimen() {
        return specimen;
    }

    public void setSpecimen(SpecimenImpl specimen) {
        this.specimen = specimen;
    }

    @Column(name = "is_deleted")
    public boolean getIsDeleted() {
        return isDeleted;
    }

    public void setIsDeleted(boolean isDeleted) {
        this.isDeleted = isDeleted;
    }

}

QWAHImage QueryDSL类的相关部分。

/**
 * QWAHImage is a Querydsl query type for WAHImage
 */
@Generated("com.querydsl.codegen.EntitySerializer")
public class QWAHImage extends EntityPathBase<WAHImage> {

    public static final QWAHImage wAHImage = new QWAHImage("wAHImage");

    public final x.y.z.db.impl.QPersistentImpl _super = new x.y.z.db.impl.QPersistentImpl(this);

    public final x.y.z.reference.census.impl.QWACensusImpl census;

    //inherited
    public final NumberPath<Long> id = _super.id;

    public final BooleanPath isDeleted = createBoolean("isDeleted");

    public final x.y.z.reference.specimen.impl.QSpecimenImpl specimen;
}

QWACensusImpl的相关部分：

/**
 * QWACensusImpl is a Querydsl query type for WACensusImpl
 */
@Generated("com.querydsl.codegen.EntitySerializer")
public class QWACensusImpl extends EntityPathBase<WACensusImpl> {

    public static final QWACensusImpl wACensusImpl = new QWACensusImpl("wACensusImpl");

    public final x.y.z.db.impl.QPersistentWithIDImpl _super = new x.y.z.db.impl.QPersistentWithIDImpl(this);

    //inherited
    public final NumberPath<Long> id = _super.id;

    public final StringPath name1 = createString("name1");

    public final StringPath name2 = createString("name2");

    public final StringPath name3 = createString("name3");

    public final StringPath name4 = createString("name4");

    // extraneous parts omitted.
}

1 个答案:

答案 0 :(得分：0)

经过一些广泛的背景调查后，我的用例似乎有a long history，仍然是common one。

要解决此问题，我可以{（3）} get access to the EntityManager Spring Data JPA，然后使用LEFT JOINs构建查询，之后我应该可以使用COALESCE ImagePredicates.orderByName(Pageable)中的关键字。

或者，（以及我决定使用的方法）我在ImageRepository.findAllByIsDeleted(boolean, Pageable)上使用Spring Data @Query：

public interface ImageRepository extends JpaRepository<WAHImage, Long>,
        QueryDslPredicateExecutor<WAHImage> {
    @Query("select i from WAHImage i " +
            "left join i.specimen s " +
            "left join i.census c " +
            "left join i.author a " +
            "left join i.copyright co " +
            "left join i.allowedUse au " +
            "where i.isDeleted = ?1 " +
            "order by coalesce(s.genus, c.name1) asc, " +
            "coalesce(s.species, c.name2) asc, " +
            "coalesce(s.infraspecies, c.name4, c.name3) asc")
    Page<WAHImage> findAllByIsDeleted(boolean isDeleted, Pageable page);
}
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