Object of type 'System.Reflection.ParameterInfo' cannot be converted to type 'System.Int32'

Question

I'm trying to write an extension method for objects that will dump the structure of the object to the debug output. I'm running in to a problem when the propertyInfo is indexed (GetIndexParameters().Length >0).

I've tried using the following:

object value = propInfo.GetValue(myObject, propInfo.GetIndexParameteres());

this results in the following runtime error:

• Object of type 'System.Reflection.ParameterInfo' cannot be converted to type 'System.Int32'

Anyone got any ideas? The full code for the method is below:

[System.Diagnostics.Conditional("DEBUG")]
public static void DebugObject(this object debugObject)
{
    System.Diagnostics.Debug.WriteLine("Debugging object: " + debugObject.GetType().Namespace);
    System.Diagnostics.Debug.WriteLine(String.Format("> {0}", debugObject.GetType()));
    System.Diagnostics.Debug.Indent();
    try
    {
        if (debugObject.GetType().IsArray)
        {
            object[] array = ((object[])debugObject);

            for (int index = 0; index < array.Length; index++)
            {
                System.Diagnostics.Debug.WriteLine(String.Format("- {{0}} = [{1}]", index, array[index]));
            }
            return;
        }

        object value = null;
        foreach (System.Reflection.PropertyInfo propInfo in debugObject.GetType().GetProperties())
        {
            try
            {
                if (propInfo.IsIndexed())
                {
                    System.Diagnostics.Debug.WriteLine(propInfo.ReflectedType.IsArray + " is indexed");
                    // THIS IS WHERE IT CHOKES.  As an example, try sending in something of type System.Net.Mail.MailMessage;
                    value = propInfo.GetValue(debugObject, propInfo.GetIndexParameters());
                }
                else
                {
                    value = propInfo.GetValue(debugObject, null);
                }

                if (value != null)
                {
                    System.Diagnostics.Debug.WriteLine(String.Format("> {0} = [{1}]", propInfo.Name, value));

                    if (
                            (value.GetType() != typeof(string))
                            &&
                            (value.GetType() != typeof(int))
                        )
                    {
                        value.DebugObject();
                    }
                }
            }
            catch (System.Reflection.TargetParameterCountException tpce)
            {
                System.Diagnostics.Debug.WriteLine(
                    String.Format(
                        "> Could not run GetValue for {1} (type '{0}', '{2}') because of incorrect prarmeters", 
                        propInfo.GetType().ToString(),
                        propInfo.Name,
                        propInfo.PropertyType.Namespace
                        )
                    );
            }
        }
    }
    finally
    {
        System.Diagnostics.Debug.Unindent();
    }
}

Answer 1

You are essentially trying to access SomeProp[foo, bar...]... so; what are sensible index values? For integers, maybe 0,0,0... is safe - maybe not. It depends on the context. Personally, I'm not sure that this is the best way to go; I might look at IList on the main object, but other than that - just look at regular properties...

Answer 2

It's bad idea to dump indexer properties. It's similar to "dump method". It's just imposible.

Also consider using PropertyInfo.CanRead before trying to get value.