为什么EF尝试在id列中插入NULL？ [英] Why is EF trying to insert NULL in id-column?

问题描述

我正在使用Entity Framework 4.0（Model First）编写我的项目。
在项目开始时，我遇到这个问题：我试图将填充的对象插入到数据库中，但我得到一个例外：

无法将值NULL插入列CategoryId，表ForumDB.dbo.Categories;列不允许为空INSERT failed。该语句已被终止。

  Category usingCategory = new Category（Using Forums，\"forforum，0）; 
 using（Context）
 {
 Context.Categories.AddObject（usingCategory）; 
 Context.SaveChanges（）; 
} 
  

我检查了这个对象，我确定它已经被填充了。 p>

以防万一：

  public Category（string name，string urlName， int index）
 {
 CategoryId = Guid.NewGuid（）; 
 Name = name; 
 UrlName = urlName; 
 CategoryIndex = index; 
} 
  

请告诉我发生了什么？
感谢任何帮助！

解决方案

看看这个： https://stackoverflow.com/a/5338384/171703 - 实体框架可能假设您的CategoryId字段是一个身份，因此传递给数据库，期望它填写给你。

Sorry for my English.

I am writing my project using Entity Framework 4.0 (Model first). At the beginning of the project, I faced with this problem: I am trying to insert the filled object in the database, but I get an exeption:

"Cannot insert the value NULL into column 'CategoryId', table 'ForumDB.dbo.Categories'; column does not allow nulls. INSERT fails. The statement has been terminated."

    Category usingCategory = new Category("Using Forums", "usingforums", 0);
    using (Context)
    {
        Context.Categories.AddObject(usingCategory);
        Context.SaveChanges();
    }

I checked this object, and I am sure that it is filled.

Just in case:

public Category(string name, string urlName, int index)
{
    CategoryId = Guid.NewGuid();
    Name = name;
    UrlName = urlName;
    CategoryIndex = index;
}

Please tell me what is going on? Thanks for any help!

解决方案

Have a look at this: https://stackoverflow.com/a/5338384/171703 - entity framework might be assuming that your CategoryId field is an identity and therefore passing null to the database expecting it to fill it for you.

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