C#主表单引用异常

Question

我创建了一个UserControl并希望添加MainForm引用

  public partial class ConsolePage : UserControl
{
    public synForm mainForm = new synForm();

    public ConsolePage(synForm parentForm)
    {
        mainForm = parentForm();
        InitializeComponent();
    }

所以，问题是，只要我用C#代码创建UserControl（在哪里创建并不重要），它就可以很好地工作，但是当我试图从工具箱中从设计器中添加他时，我就会遇到一个异常。

我知道，我应该这样称呼他们

MyControl whatever = new MyControl(this); 

我知道如果我想从工具箱添加myControl,我应该在Form.Designer中纠正这个错误！

别恨我，我是编程和拼写方面的新手

编辑:<<<<<<

忘了写出我得到的错误：

System.ComponentModel.Design.Serialization.DesignerSerializationManager.CreateInstance(Type type, ICollection arguments, String name, Boolean addToContainer)

System.ComponentModel.Design.Serialization.DesignerSerializationManager.System.ComponentModel.Design.Serialization.IDesignerSerializationManager.CreateInstance(Type type, ICollection arguments, String name, Boolean addToContainer)

System.ComponentModel.Design.Serialization.CodeDomSerializerBase.DeserializeInstance(IDesignerSerializationManager manager, Type type, Object[] parameters, String name, Boolean addToContainer)

System.ComponentModel.Design.Serialization.ComponentCodeDomSerializer.DeserializeInstance(IDesignerSerializationManager manager, Type type, Object[] parameters, String name, Boolean addToContainer)

System.ComponentModel.Design.Serialization.CodeDomSerializerBase.DeserializeExpression(IDesignerSerializationManager manager, String name, CodeExpression expression)

System.ComponentModel.Design.Serialization.CodeDomSerializer.DeserializeStatementToInstance(IDesignerSerializationManager manager, CodeStatement statement)
 System.ComponentModel.Design.Serialization.CodeDomSerializer.Deserialize(IDesignerSerializationManager manager, Object codeObject)
bei System.Windows.Forms.Design.ControlCodeDomSerializer.Deserialize(IDesignerSerializationManager manager, Object codeObject)

System.ComponentModel.Design.Serialization.TypeCodeDomSerializer.DeserializeName(IDesignerSerializationManager manager, String name, CodeStatementCollection statements) 

Answer 1

如果不知道错误消息（您只提供了堆栈跟踪）和parentForm（）的内容，就不那么容易说了。但看起来parentForm（）正在做设计器中不可能做的事情。

因此，您可以通过检查DesignMode（https://docs.microsoft.com/en-us/dotnet/api/system.componentmodel.component.DesignMode？redirectedfrom=msdn&view=netframework-4.7.2#system_componentmodel_component_designMode）来尝试不在设计模式下执行parentForm（）。

public ConsolePage()
    {
        if (!DesignMode)
        {
            mainForm = parentForm();
        }
        InitializeComponent();
    }