Data Rest Repository 自定义注释查询

Question

我正在阅读 Spring Data-Rest 指南并努力编写自定义带注释的查询，但不确定是否可行，代码如下：

CategoryRepository

package com.example.repositories

import org.springframework.data.domain.Page
import org.springframework.data.domain.Pageable
import org.springframework.data.jpa.repository.JpaRepository
import org.springframework.data.jpa.repository.Query
import org.springframework.data.repository.query.Param
import org.springframework.data.rest.core.annotation.RepositoryRestResource
import org.springframework.data.rest.core.annotation.RestResource

import com.example.entities.Category
import com.example.entities.InventoryDetail

@RepositoryRestResource(collectionResourceRel="categories", path="categories")
interface CategoryRepository extends JpaRepository<Category, Long> {

    @RestResource(path="inventoryByCategory",rel="inventoryByCategory")
    @Query("select new com.example.entities.InventoryDetail(i.id, i.item, c.name) from Category c join c.inventory i where upper(c.name) like upper(:name+'%')")
    Page<InventoryDetail> queryByCategoryStartsWithIgnoreCase(@Param("name") String name, Pageable pageable)

}

上面的查询是我正在努力解决的问题，不知道如何正确执行此操作。我搜索了几个小时寻找解决方案，但找不到。

类别实体

package com.example.entities

import javax.persistence.Column
import javax.persistence.Entity
import javax.persistence.FetchType
import javax.persistence.GeneratedValue
import javax.persistence.GenerationType
import javax.persistence.Id
import javax.persistence.JoinColumn
import javax.persistence.OneToMany
import javax.persistence.Table

@Entity
@Table(name="categories")
class Category implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    long id

    @Column
    String name

    @Column
    String description

    @OneToMany(targetEntity=Inventory.class, fetch=FetchType.LAZY)
    @JoinColumn(name="category")
    List<Inventory> inventory

}

库存实体

package com.example.entities

import javax.persistence.Column
import javax.persistence.Entity
import javax.persistence.GeneratedValue
import javax.persistence.GenerationType
import javax.persistence.Id
import javax.persistence.Index
import javax.persistence.Table

@Entity
@Table(name="inventory", indexes=[ @Index(columnList="category", unique=false) ])
class Inventory implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    long id

    @Column
    long category

    @Column
    String item

    @Column
    String description

    @Column
    long price

    @Column
    long onHand
}

库存详情

package com.example.entities

import javax.persistence.Column;

class InventoryDetail {

    long id

    String item

    String name

    InventoryDetail(long id, String item, String name) {
        this.id = id
        this.item = item
        this.name = name
    }

}

如果我想从两个实体中选择特定字段，我是否需要像上面的那样有一个自定义 DTO？是否可以只使用new map(...)？无论哪种方式，查询都会运行并且我在控制台中看到它，但是在 HAL 浏览器中它给了我一个 500 错误，我确定我忽略了某些东西，但不确定它是什么。

提前感谢您的帮助！

编辑

这是 Hibernate 查询的输出：

Hibernate: select count(category0_.id) as col_0_0_ from categories category0_ inner join inventory inventory1_ on category0_.id=inventory1_.category where upper(category0_.name) like upper(?+'%')
Hibernate: select inventory1_.id as col_0_0_, inventory1_.item as col_1_0_, category0_.name as col_2_0_ from categories category0_ inner join inventory inventory1_ on category0_.id=inventory1_.category where upper(category0_.name) like upper(?+'%') limit ?

Answer 1

经过无数小时的测试，我决定将代码放入控制器中并通过 EntityManager 访问它，它成功了。从控制器开始工作后，我意识到 JPA/Hibernate 期望的是实体而不是对象/DTO。

我能够做到这一点......

List<Object> list(String name) {
    def qry = "select new map(i.id as id, i.item as item, c.name as category) from Category c join c.inventory i where upper(c.name) like upper(:name+'%')"
    List<Object> results = em.createQuery(qry).setParameter('name',name).getResultList()
    return results
}

Answer 2

您的查询：

@Query("select new com.example.entities.InventoryDetail(i.id, i.item, c.name) from Category c join c.inventory i where upper(c.name) like upper(:name+'%')")

在您的自定义查询中，类别和库存没有连接映射。通过以下方式替换这行代码：Category 和 Inventory 在 join 中由它们的 id 映射：

 @Query("select new com.example.entities.InventoryDetail(i.id, i.item, c.name) from Category c join c.inventory i where c.id=i.category upper(c.name) like upper(:name+'%')")

注意：jpql 默认join 表示inner join

Answer 3

我不确定这是否是您的 500 错误的原因，但我发现您的查询有问题，尤其是您如何将参数 name 与通配符 % 连接起来。

@Query("select new com.example.entities.InventoryDetail(i.id, i.item, c.name) from Category c join c.inventory i where upper(c.name) like upper(:name+'%')")

您必须删除加号和单引号。

@Query("select new com.example.entities.InventoryDetail(i.id, i.item, c.name) from Category c join c.inventory i where upper(c.name) like upper(:name%)")

查看示例实现here。