确定是否可以为反射属性分配给定值

Question

What is the easiest way to determine if a reflected property can be assigned a given value ?

The method signature of what I need is :

public static bool IsAssignable(PropertyInfo property, object value)
{        
    throw new NotImplementedException();
}

This method should work for value type and reference type and weither value is null or not.

Thanks for you help guys.

Manitra.

Answer 1

您可能正在寻找Type.IsAssignableFrom

Answer 2

You can't determine the type of null which is passed as object . You only can say if the property is able to take null at all.

You could take the compile-time type for that reason:

public static bool IsAssignable<T>(PropertyInfo property, T value)
{        
    if (value != null)
    {
        return property.PropertyType.IsAssignableFrom(value.GetType());
    }
    return property.PropertyType.IsAssignableFrom(typeof(T));
}

Answer 3

Thanks to Stefan's and John responses, and the "Determine if a reflected property can be assigned null" question, here is the code I'll use :

public static bool IsAssignable(PropertyInfo property, object value)
{
    if (value == null && property.PropertyType.IsValueType && Nullable.GetUnderlyingType(property.PropertyType) == null)
        return false;
    if (value != null && !property.PropertyType.IsAssignableFrom(value.GetType()))
        return false;
    return true;
}

This works for all cases and in a pure loosely typed fashion.

Manitra.