无法插入NULL值插入列在ASP.NET MVC实体框架 [英] Cannot insert the value NULL into column in ASP.NET MVC Entity Framework

问题描述

当尝试使用此code：

When trying to use this code:

var model = new MasterEntities();

var customer = new Customers();
customer.Sessionid = 25641;

model.Customers.Add(customer);
model.SaveChanges();

我得到：

{无法插入NULL值插入列'SESSIONID'，表
  master.dbo.Column';列不允许空值。插
  失败。\\ r \\ n此语句已终止。}

{"Cannot insert the value NULL into column 'Sessionid', table 'master.dbo.Column'; column does not allow nulls. INSERT fails.\r\nThe statement has been terminated."}

列的SessionID其实是主键，标有[KEY]是这样的：

The column "Sessionid" is actually the primary key and is marked with [KEY] like this:

 public class Customers
    {   
        [Key]
        public long Sessionid { get; set; }
        public long? Pers { get; set; }
    }

所以，根据<一个href=\"http://stackoverflow.com/questions/18470736/cannot-insert-the-value-null-into-column-roleid-mvc4-simple-membership\">this问题，它好像当属性被标记 [KEY] ，EF忽略了我自己的SessionID的声明，因为它期望的数据库分配的值。

So according to this question, it seems as if when the property is marked with [KEY], EF ignores my own declaration of Sessionid since it expects the database to assign the value.

所以，我怎么能解决这个问题？如果我删除 [KEY] 我得到的实体类型没有定义键例外...

So how can I solve this? If I remove [KEY] I get the "entity type has no key defined" exception...

推荐答案

我解决它通过添加 [DatabaseGenerated（DatabaseGeneratedOption.None）] 是这样的：

I solved it by adding [DatabaseGenerated(DatabaseGeneratedOption.None)] like this:

public class Customers
    {   
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.None)]
        public long Sessionid { get; set; }
        public long? Pers { get; set; }
    }

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