代码第一 - 无法将值NULL插入列'Id' [英] Code first - Cannot insert the value NULL into column 'Id'

问题描述

这是我的代码，非常简单...

This is my code, very simple...

 var newUser = new User();
        newUser.Id=id;
        newUser.Email = email;
       this.DataContext.Set<User>().Add(newUser);
        this.DataContext.SaveChanges();

我得到的错误是在 this.DataContext.SaveChanges（） ; 表示：

The error I get is a sqlexception at this.DataContext.SaveChanges(); stating that:

无法将值NULL插入列Id，表
' xxxxx.dbo.Users';列不允许为空。 INSERT failed。

Cannot insert the value NULL into column 'Id', table 'xxxxx.dbo.Users'; column does not allow nulls. INSERT fails.

我已调试，发现Id&电子邮件在newUser
this.DataContext.Set< User>（）。Add（newUser）;

I have debugged and found that there is value in Id & Email in newUser at this.DataContext.Set<User>().Add(newUser);

如果是这种情况，值如何变为null？

If this is the case, how is the value becoming null?

错误堆栈跟踪：

[DbUpdateException: An error occurred while updating the entries. See the inner exception for details.]
   System.Data.Entity.Internal.InternalContext.SaveChanges() +204
   System.Data.Entity.Internal.LazyInternalContext.SaveChanges() +23
   System.Data.Entity.DbContext.SaveChanges() +20

我无法理解或解决这个问题....

I have not been able to understand or solve this....

真诚感谢任何帮助...

Would sincerely appreciate any help in this...

Regards
Arnab

Regards Arnab

解决方案

好的，谢谢Ladislav指点我正确的方向：
添加属性 [DatabaseGenerated（DatabaseGeneratedOption.None）] 解决了问题。

Ok, thanks to Ladislav to point me in the right direction: Adding the attribute [DatabaseGenerated(DatabaseGeneratedOption.None)] solved the problem.

推荐答案

参考这篇文章似乎实体框架预计默认插入到标识列。

Referring to this post it seems that entity framework expects by default that you insert into identity column.

要解决这个问题：

modelBuilder.Entity<BOB>()
    .HasKey(p => p.Id)
    .Property(p => p.Id)
    .StoreGeneratedPattern = StoreGeneratedPattern.None;

builder.Entity<BOB>().MapSingleType().ToTable("BOB");

或在POCO中装饰您的密钥：

or decorate your key in the POCO with:

[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)] //Fixed typo
public Int64 PolicyID { get; set; }

这篇关于代码第一 - 无法将值NULL插入列'Id'的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！