单向Manytomany JPA规范
我有以下实体 StockItem，产品和productCategory。
stockitem与产品- 产品单向带有
productcategory
procem> process> product class class没有参考的参考productCategory，但是productCategory收集了product
我想使用JPS规范来查询给定的ProductCategory
类的概述，如下所示。
库存项目类看起来像是
@Entity
public class StockItem {
...
@ManyToOne
private Product product;
...
}
产品类骨骼
@Entity
public class Product {
...
private String productName;
...
}
产品类别的类别如下：
@Entity
public class ProductCategory {
...
@NotNull
private String categoryName;
@ManyToMany
@NotNull
private Set<Product> products = new HashSet<>();
...
}
我想根据ProductCategoryId查询SalelineItems。我尝试了一个，但我坚持以下代码。
public List<SaleLineItem> findAllByProductCategory(LongFilter productCategoryFilter,
Specification<SaleLineItem> specification) {
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<SaleLineItem> cq = cb.createQuery(SaleLineItem.class);
Root<ProductCategory> productCategoryRoot = cq.from(ProductCategory.class);
ListJoin<ProductCategory, Product> lj = productCategoryRoot.joinList(ProductCategory_.PRODUCTS);
Root<StockItem> stockItemRoot = cq.from(StockItem.class);
Join<StockItem, Product> kl = stockItemRoot.join(StockItem_.product);
// How to combine lj and kl :)
return null;
}
实现这一目标的方法是什么？
I have the following entitiesStockItem, Product and ProductCategory.
StockItemManyToOne withProductProductUnidirectional ManyToMany withProductCategory
Product class has no reference of ProductCategory, but ProductCategory has collection of Product
I wanted to use JPS specification to query StockItems for a given ProductCategory
Class outlines are as below.
STOCK ITEM class looks like
@Entity
public class StockItem {
...
@ManyToOne
private Product product;
...
}
PRODUCT class skeleton
@Entity
public class Product {
...
private String productName;
...
}
PRODUCT CATEGORY is as follows
@Entity
public class ProductCategory {
...
@NotNull
private String categoryName;
@ManyToMany
@NotNull
private Set<Product> products = new HashSet<>();
...
}
I wanted to query SaleLineItems based on productCategoryId. I made an attempt but am stuck with the following code.
public List<SaleLineItem> findAllByProductCategory(LongFilter productCategoryFilter,
Specification<SaleLineItem> specification) {
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<SaleLineItem> cq = cb.createQuery(SaleLineItem.class);
Root<ProductCategory> productCategoryRoot = cq.from(ProductCategory.class);
ListJoin<ProductCategory, Product> lj = productCategoryRoot.joinList(ProductCategory_.PRODUCTS);
Root<StockItem> stockItemRoot = cq.from(StockItem.class);
Join<StockItem, Product> kl = stockItemRoot.join(StockItem_.product);
// How to combine lj and kl :)
return null;
}
What would be the way to achieve this?
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将为您提供链接表所需的谓词，您可以将其作为谓词返回，以便使用方法。
另外，您可以使用它来定义LT上的JOIN语句：
但是如果您返回null，我不知道弹簧如何处理查询。
Will give you the predicate you need to link your tables which you can return as the predicate for your method to use.
Alternatively, you can use it to define the join statement on lt using:
but I don't know how Spring handles the query if you return null.