why Type.GetType() return null

Question

I have a class named "Criteria", a Repository named CriteriaReposiroty.

CriteriaReposiroty reads a xml file and returns a list of Criteria

       public static Func<XElement, Criteria> BuildObjectFromXElement(string typeName)
    {
        ParameterExpression element = Expression.Parameter(typeof(XElement), "element");

        List<MemberBinding> bindings = new List<MemberBinding>();

        foreach (PropertyInfo prop in GetWritableProperties(Type.GetType(typeName)))
        {
            MethodCallExpression propertyValue = Expression.Call(
                typeof(XElementAttributeHelper).GetMethod("GetAttributeValue").MakeGenericMethod(prop.PropertyType), element,
                Expression.Constant(prop.Name));

            MemberBinding binding = Expression.Bind(prop, propertyValue);

            bindings.Add(binding);
        }

        Expression initializer = Expression.MemberInit(Expression.New(Type.GetType(typeName)), bindings);

        return Expression.Lambda<Func<XElement, Criteria>>(initializer, element).Compile();

    }

    public static IEnumerable<PropertyInfo> GetWritableProperties(Type t)
    {
        foreach (PropertyInfo property in t.GetProperties())
        {
            if (property.CanWrite)
                yield return property;
        }
    }
public static T GetAttributeValue<T>(this XElement element, string attrName)
    {
        foreach (XAttribute attribute in element.Attributes())
        {
            if (string.Compare(attribute.Name.ToString(), attrName, true, CultureInfo.InvariantCulture) == 0)
            {
                if (string.IsNullOrEmpty(attribute.Value))
                    return default(T);

                TypeConverter converter = TypeDescriptor.GetConverter(typeof(T));
                return (T)converter.ConvertFromString(attribute.Value);

            }
        }

        return default(T);
    }

when I call Type.GetType("Criteria"), it always returns null.

can anyone help?

Thanks in Advance

Answer 1

You have to include the namespace:

Type type = Type.GetType("YourNamespace.Criteria");

This will only work if your class is within the executing assembly. If it's from another assembly, you'll have to use a qualified assembly name. It looks like you should be able to just use the Type name prefixed with the namespace though in your scenario.

Answer 2

You should probably include the namespace as well:

namespace SomeNamespace
{
    class TheClass { } 
}


Type.GetType("TheClass"); // returns null
Type.GetType("SomeNamespace.TheClass"); // returns a Type object

Answer 3

I found the bug, it's a miserable typo error.