Asp.net mvc 未生成实体框架查询
我有以下对象模型:Asp.net mvc 未生成实体框架查询,asp.net-mvc,entity-framework,Asp.net Mvc,Entity Framework,我有以下对象模型: [Table("APA_QuestionProduct")] public class QuestionProduct { [Key, ForeignKey("Question"), Column(Order=0)] public int QuestionID { get; set; } [ForeignKey("QuestionID")] public Question Question { get; set; } [Key, Fo
[Table("APA_QuestionProduct")]
public class QuestionProduct
{
[Key, ForeignKey("Question"), Column(Order=0)]
public int QuestionID { get; set; }
[ForeignKey("QuestionID")]
public Question Question { get; set; }
[Key, ForeignKey("Product"), Column(Order=1)]
public int ProductID { get; set; }
[ForeignKey("ProductID")]
public Product Product { get; set; }
}
表:
USE [qbm]
GO
/****** Object: Table [dbo].[APA_QuestionProduct] Script Date: 5/21/2013 6:52:46 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[APA_QuestionProduct](
[QuestionID] [int] NOT NULL,
[ProductID] [int] NOT NULL,
CONSTRAINT [PK_APA_QuestionProduct] PRIMARY KEY CLUSTERED
(
[QuestionID] ASC,
[ProductID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[APA_QuestionProduct] WITH CHECK ADD CONSTRAINT [FK_APA_QuestionProduct_APA_Product] FOREIGN KEY([ProductID])
REFERENCES [dbo].[APA_Product] ([ProductID])
GO
ALTER TABLE [dbo].[APA_QuestionProduct] CHECK CONSTRAINT [FK_APA_QuestionProduct_APA_Product]
GO
ALTER TABLE [dbo].[APA_QuestionProduct] WITH CHECK ADD CONSTRAINT [FK_APA_QuestionProduct_APA_Question] FOREIGN KEY([QuestionID])
REFERENCES [dbo].[APA_Question] ([QuestionID])
GO
ALTER TABLE [dbo].[APA_QuestionProduct] CHECK CONSTRAINT [FK_APA_QuestionProduct_APA_Question]
GO
因此后面的表只有2个外键(也是主键)。我的问题对象有一个产品列表。当我更新ProductID外键并在上下文上调用“SaveChanges”时,数据库中不会生成任何查询/更新:
question.Products[1].ProductID = 4;
db.Entry(question.Products[1]).State = EntityState.Modified;
db.SaveChanges();
我查看了InteliTrace以检查查询,但即使我的QuestionProduct对象发生了更改,也不会对我的QuestionProduct表调用任何查询。为什么不更新该表?不会引发任何错误。您的实体
QuestionProduct
仅包含键属性,不包含其他标量属性。实体框架不允许更改(主)键属性
您必须删除旧的链接记录并创建新的链接记录以建立新关系,例如:
QuestionProduct oldProduct = question.Products[1];
QuestionProduct newProduct = new QuestionProduct
{
QuestionID = question.QuestionID,
ProductID = 4
};
db.QuestionProducts.Attach(oldProduct);
db.QuestionProducts.Remove(oldProduct);
db.QuestionProducts.Add(newProduct);
db.SaveChanges();
但你真的应该把它建模为多对多关系。您不需要QuestionProduct
实体,并且可以拥有直接从Question
引用到Product
的集合,反之亦然,而无需通过中间实体导航
例如,它显示了它是如何工作的