实体框架4错误：无法更新EntitySet，因为它具有DefiningQuery [英] Entity Framework 4 Error: Unable to update the EntitySet because it has a DefiningQuery

问题描述

好吧，这是这个场景。我有3张桌子一个叫做aspnet_Users，一个叫做Categories，一个称为User_Categories的链接表。 aspnet_Users和Categories都有主键（分别为UserId和ID）。链接表只有两列：CategoryID和UserId，并且每个列都有外键关系设置，我有一个唯一的密钥设置，用于User_Categories上的两列。这将建立aspnet_Users表和Categories表之间的多对多关系。我从这个数据库设置生成了我的实体edmx文件，一切看起来都很完美，适用于几乎所有的操作。

我想做的是从一个表单中添加一个新的类别（其本身完美地工作），同时，将特定用户与新提交的类别相关联。当我尝试这样做，我得到错误在我的主题行。这是我用来尝试这个的代码（ctx是我的实体上下文对象）：

  public ActionResult Create（Category category ，Guid userId）
 {
 aspnet_Users user = ctx.aspnet_Users.SingleOrDefault（x => x.UserId == userId）; 
 ctx.Categories.AddObject（category）; 
 user.Categories.Add（category）; 
 ctx.SaveChanges（）;; 
 return RedirectToAction（Index）; 
} 
  

为什么这不工作？

解决方案

我假设完整的异常消息类似于：

更新EntitySet YourTableName ，因为它有一个DefiningQuery，而且在ModificationFunctionMapping元素中不存在InsertFunction元素以支持当前操作。

如果您的DB表没有定义主键，则会发生这种情况。

将主键添加到表中（使用SQL Server Management Studio或任何），并从数据库更新您的 .edmx 模型。

Okay, here's the scenario. I have 3 tables. One called aspnet_Users one called Categories and a linking table called User_Categories. aspnet_Users and Categories both have primary keys (UserId and ID respectively). The linking table has only two columns: CategoryID and UserId, and there are foreign key relationships setup for each column AND I have a unique key setup for the two columns on User_Categories. This sets up a many-to-many relationship between the aspnet_Users table and the Categories table. I generated my entities edmx file from this database setup, and everything looks perfect and works for almost all operations.

What I want to do is add a new category from a form (which works perfecly by itself), and also, at the same time, associate a specific user with that newly submitted category. When I try to do this I get the error in my subject line. Here is the code I'm using to try this (ctx is my entities context object):

public ActionResult Create(Category category, Guid userId)
{
    aspnet_Users user = ctx.aspnet_Users.SingleOrDefault(x => x.UserId == userId);
    ctx.Categories.AddObject(category);
    user.Categories.Add(category);
    ctx.SaveChanges();;
    return RedirectToAction("Index");
}

Why doesn't this work?

解决方案

I assume the full exception message is something similar to:

Unable to update the EntitySet YourTableName because it has a DefiningQuery and no InsertFunction element exists in the ModificationFunctionMapping element to support the current operation.

This will occur if your DB's table doesn't have a primary key defined.

Add a primary key to your table (using SQL Server Management Studio or whatever), and update your .edmx model from the database.

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