PropertyInfo SetValue and nulls

Question

If I have something like:

object value = null;
Foo foo = new Foo();

PropertyInfo property = Foo.GetProperties().Single(p => p.Name == \"IntProperty\");
prope         


        

Answer 1

You can use PropertyInfo.PropertyType.IsAssignableFrom(value.GetType()) expression to determine whether specified value can be written into property. But you need to handle case when value is null, so in this case you can assign it to property only if property type is nullable or property type is reference type:

public bool CanAssignValueToProperty(PropertyInfo propertyInfo, object value)
{
    if (value == null)
        return Nullable.GetUnderlyingType(propertyInfo.PropertyType) != null ||
               !propertyInfo.IsValueType;
    else
        return propertyInfo.PropertyType.IsAssignableFrom(value.GetType());
}

Also, you may find useful Convert.ChangeType method to write convertible values to property.

Answer 2

If you have the PropertyInfo, you can check the .PropertyType; if .IsValueType is true, and if Nullable.GetUnderlyingType(property.PropertyType) is null, then it is a non-nullable value-type:

        if (value == null && property.PropertyType.IsValueType &&
            Nullable.GetUnderlyingType(property.PropertyType) == null)
        {
            throw new InvalidCastException ();
        }