如何按实体的集合值查询实体 [英] How to query for entities by their collection value

问题描述

我使用jpa，我有以下实体：

I'm using jpa and I have the following entity:

@Entity
@Table(name="favorites_folders")
public class FavoritesFolder {

     private static final long serialVersionUID = 1L;

     @Id
     private String id;

     @NotNull
     @Size(min = 1, max = 50)
     public String name;

     @ElementCollection(fetch = FetchType.LAZY)
     @CollectionTable(
        name="favorites_products",
        joinColumns=@JoinColumn(name="folder_id")
        )
     @Column(name="product_id")
     @NotNull
     private Set<String> productsIds = new HashSet<String>();
}

我想要做的是获取一组 FavoritesFolder 在 productsIds 成员集中包含字符串favorite-id的实体。

What I want to do is to get a set of FavoritesFolder entities that contains the string "favorite-id" in their productsIds member set.

有没有人知道如何在 criteria api 中执行此操作？

Does anyone know how can it be done in criteria api?

更新：

我想以下sql应该做的伎俩，但我不知道如何在 JPQL 或 Criteria API 中执行：

select * from favorites_folders join favorites_products on favorites_folders.id = favorites_products.folder_id where favorites_products.product_id = 'favorite-id'

推荐答案

要获取一组FavoritesFolder实体，在其productsId成员集中使用条件api包含字符串favorite-id，您应该

To get a set of FavoritesFolder entities that contains the string "favorite-id" in their productsIds member set using criteria api you should do the following:

CriteriaBuilder cb = em.getCriteriaBuilder(); //em is EntityManager
CriteriaQuery<FavoritesFolder> cq = cb.createQuery(FavoritesFolder.class);
Root<FavoritesFolder> root = cq.from(FavoritesFolder.class);

Expression<Collection<String>> productIds = root.get("productsIds");
Predicate containsFavoritedProduct = cb.isMember("favorite-id", productIds);

cq.where(containsFavoritedProduct);

List<FavoritesFolder> favoritesFolders = em.createQuery(cq).getResultList();

有关 JPQL和条件查询中的集合。

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