疯狂VS设计师错误

重命名一个类后，我的一个表单开始给我设计师的错误，拒绝打开。有趣的是，当我运行程序时，表单工作得很好。

我开始恢复我的更改以推导出问题。我现在已完全恢复到最后一次提交 - 其中知道表单在设计器中工作 - 清理解决方案，并删除bin /和obj /文件夹，以及* .suo文件以获得更好的度量。

窗体仍然不显示在设计器中。

下面是它给人的错误：

Could not find 'MyNamespace.MyControl'. Please make sure that the assembly that contains this type is referenced. If this type is a part of your development project, make sure that the project has been successfully built.

The variable 'myControl1' is either undeclared or was never assigned.

的变量都宣布和分配，以及MyControl建立精细（再次，窗体时程序实际运行正常工作）。更奇怪的是，如果我尝试创建一个新的形式，并将一个MyControl到它，我得到这个实体框架错误：

Failed to create component 'MyControl'. The error message follows: 'System.ArgumentException: The specified named connection is either not found in the configuration, not intended to be used with the EntityClient provider, or not valid. at System.Data.EntityClient.EntityConnection.ChangeConnectionString(String newConnectionString) at System.Data.EntityClient.EntityConnection..ctor(String connectionString) at System.Data.Objects.ObjectContect.CreateEntityConnection(String connectionString) etc. etc.

有什么错我的连接字符串：它的工作之前，并再次， 它在我实际运行程序（该控件已经存在于上一次提交的旧窗体上）时起作用。

任何想法任何？我完全不知所措。

[编辑] 唯一显著代码：

MyControl.cs 
public MyControl() 
{ 
    _entities = new MyEFEntities(); //Entity-framework generated class 
} 

MyForm.Designer.cs 
private void InitializeComponent() 
{ 
    this.myControl1 = new MyNamespace.MyControl(); 
    ... 
    this.Controls.Add(this.myControl1); 
} 

MyEFDatabase.Designer.cs 
public MyEFEntities() : base("name=MyEFEntities", "MyEFEntities") { ... } 

App.Config 
<connectionStrings> 
    <add name="MyEFEntities" connectionString="metadata=res://*/MyEFDatabase.csdl|res://*/MyEFDatabase.ssdl|res://*/MyEFDatabase.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=MyDatabaseServer;Initial Catalog=MyDatabase;Integrated Security=True;MultipleActiveResultSets=True&quot;" providerName="System.Data.EntityClient" /> 
</connectionStrings>

我已经试过“替换"与'”绝招 - 没有帮助。

[EDIT2]这是发生在新项目也有，但是不会立即进行。只有在摆弄了一下之后（这与添加EF自己无法解决的多对一关系有关），但我无法弄清楚重现的确切步骤。

来源

2010-03-16 BlueRaja - Danny Pflughoeft

通常遇到这种情况时我只需重新启动VS和错误随风 – Luiscencio 2010-03-16 17:31:26

没有运气走开 - 刚刚完成重新启动我的电脑，它仍然发生。 – 2010-03-16 17:36:56

mmmm my next guess = P .... are namespaces OK？ – Luiscencio 2010-03-16 17:39:45

我发布了一个错误报告，以及一个解决方法here。

The only workaround is to create the EF_Entities within the form, and pass it in as a parameter to the control.

This workaround no longer works if the parameter is a member of a parent of the control ie. MyChildControl : MyParentControl, MyParentControl : UserControl, EF_EntitiesParameter member of MyParentControl. The designer crashes with the error "Object reference not set to an instance of an object"; futher inspection shows that the designer is running code that requires EF_EntitiesParameter, which for some reason is set to null (it is being correctly set in the form's constructor, and works fine when actually running).

The workaround to this problem is to prevent all code that requires the use of EF_EntitiesParameter from running in the designer (See workarounds here)

来源

2010-04-05 17:03:58