由于DbContext处理错误，操作无法完成 [英] The operation cannot be completed because the DbContext has been disposed error

问题描述

我是EF的新手，我试图使用一个扩展方法，它从我的数据库类型 User 转换到我的信息类 UserInfo 。

如果有差异，我先使用数据库？

我的代码如下给出错误

由于DbContext已被处理，操作无法完成。

  try 
 {
 IQueryable< User>用户; 
 using（var dataContext = new dataContext（））
 {
 users = dataContext.Users 
 .Where（x => x.AccountID == accountId&& x .IsAdmin == false）; 
 if（users.Any（）== false）
 {
 return null; 
} 
} 
 return users.Select（x => x.ToInfo（））ToList（）; //这行是问题
} 
 catch（Exception ex）
 {
 // ... 
} 
  

我可以看到为什么会这样做，但是我也不明白为什么where语句的结果没有被保存到用户对象？

所以我想我的主要问题是为什么它不工作，其次是什么是正确的方式使用扩展方法和EF？

解决方案

这个

  try 
 {
 IQueryable< User>用户; 
 
 using（var dataContext = new dataContext（））
 {
 users = dataContext.Users.Where（x => x.AccountID == accountId&& .IsAdmin == false）; 
 
 if（users.Any（）== false）
 {
 return null; 
} 
 else 
 {
 return users.Select（x => x.ToInfo（））ToList（）; //这行是问题
} 
} 
 
 
} 
 catch（Exception ex）
 {
 .. 
} 
  

I'm new to EF and I'm trying to use an extension method which converts from my Database type User to my info class UserInfo.
I'm using database first if that makes a difference?

My code below gives the error

The operation cannot be completed because the DbContext has been disposed.

try
{
    IQueryable<User> users;
    using (var dataContext = new dataContext())
    {
        users = dataContext.Users
                  .Where(x => x.AccountID == accountId && x.IsAdmin == false);
        if(users.Any() == false)
        {
            return null;
        }
    }
    return users.Select(x => x.ToInfo()).ToList(); // this line is the problem
}
catch (Exception ex)
{
    //...
}

I can see why it would do it, but I also don't understand why the result of the where statement isn't being saved into the users object?

So I guess my main question is why doesn't it work and secondly what's the right way of using extension methods and EF?

解决方案

This question & answer lead me to believe that IQueryable require an active context for its operation. That means you should try this instead:

try
{
    IQueryable<User> users;

    using (var dataContext = new dataContext())
    {
        users = dataContext.Users.Where(x => x.AccountID == accountId && x.IsAdmin == false);

        if(users.Any() == false)
        {
            return null;
        }
        else
        {
            return users.Select(x => x.ToInfo()).ToList(); // this line is the problem
        }
    }


}
catch (Exception ex)
{
    ...
}

这篇关于由于DbContext处理错误，操作无法完成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！