The designer must create an instance of…cannot because the type is declared abstract

Question

Visual Studio complains: Warning 1 The designer must create an instance of type \'RentalEase.CustomBindingNavForm\' but it cannot because the type is declared as abst

Answer 1

You can solve this using an attribute on your abstract class like the following

[TypeDescriptionProvider(typeof(AbstractControlDescriptionProvider))]

This will work for every case where you need it. The AbstractControlDescriptionProvider is below

public class AbstractControlDescriptionProvider : TypeDescriptionProvider
{
    public AbstractControlDescriptionProvider()
        : base(TypeDescriptor.GetProvider(typeof(TAbstract)))
    {
    }

    public override Type GetReflectionType(Type objectType, object instance)
    {
        if (objectType == typeof(TAbstract))
            return typeof(TBase);

        return base.GetReflectionType(objectType, instance);
    }

    public override object CreateInstance(IServiceProvider provider, Type objectType, Type[] argTypes, object[] args)
    {
        if (objectType == typeof(TAbstract))
            objectType = typeof(TBase);

        return base.CreateInstance(provider, objectType, argTypes, args);
    }
}