Question

在阅读了文档的Relations页后，我可以使用这样的多对多关系：

@Entity
public class Product {
    @Id private Long id;

    @ToMany
    @JoinEntity(
            entity = JoinProductsWithOrders.class,
            sourceProperty = "productId",
            targetProperty = "orderId"
    )
    private List<Order> ordersWithThisProduct;
}

@Entity
public class JoinProductsWithOrders {
    @Id private Long id;
    private Long productId;
    private Long orderId;
}

@Entity
public class Order {
    @Id private Long id;
}

现在，使用此代码，我是否可以拥有双向关系并从订单访问与之关联的产品列表？或者我应该在Order类中添加产品列表吗？像这样：

...
@Entity
public class Order {
    @Id private Long id;

    @ToMany //I don't know if this is corect btw.
    private List<Product>  productsForThisOrder;
}

Answer 1

这是你应该怎么做的：

@Entity
public class Order {
    @Id private Long id;

    @ToMany
    @JoinEntity(
        entity = JoinProductsWithOrders.class,
        sourceProperty = "orderId",
        targetProperty = "productId"
    )
    private List<Product>  productsForThisOrder;
}

如何与GreenDAO使用双向多对多关系？

1 个答案: