Cast object to T

c# generics casting
Kasper Holdum picture Kasper Holdum · May 22, 2009 · Viewed 136k times · Source

I'm parsing an XML file with the XmlReader class in .NET and I thought it would be smart to write a generic parse function to read different attributes generically. I came up with the following function:

private static T ReadData<T>(XmlReader reader, string value)
{
    reader.MoveToAttribute(value);
    object readData = reader.ReadContentAsObject();
    return (T)readData;
}

As I came to realise, this does not work entirely as I have planned; it throws an error with primitive types such as int or double, since a cast cannot convert from a string to a numeric type. Is there any way for my function to prevail in modified form?

Answer

Bob picture Bob · May 22, 2009

First check to see if it can be cast.

if (readData is T) {
    return (T)readData;
} 
try {
   return (T)Convert.ChangeType(readData, typeof(T));
} 
catch (InvalidCastException) {
   return default(T);
}

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