Question

See i have a situation like this…

object myRoledata  = List<Roles>() --> (some list or Ienumerable type)

Now i have a generic method which creates an XML object from List<T> –
Something like this..

public string GetXML<T>(object listdata)  
{  
    List<T> objLists = (List<T>)Convert.ChangeType(listData, typeof(List<T>));  
    foreach(var obj in listdata)   
    {  
        //logic to create xml  
    }  
}

Now in order to run this method I have to do like this:

string xml = GetXML<Roles>(myRoledata);

Now i dont know what Type may come to me to be passed to GetXML method. I have a method which will call GetXML for different Types e.g. Roles, Users etc

now i can get the Type within the List<> like this

Type genericType = obj.GetType().GetGenericArguments()[0];

but cannot pass it like this

string xml = GetXML<genericType>(myRoledata);

Is there anyway in which i can pass any genericTypes to GetXML method?

Answer 1

This is a problem you probably want to avoid solving. It is possible, via reflection, to call methods dynamically without statically resolving them – but it kind of defeats the whole point of the type-annotations.

Either do this:

public string GetXML(IEnumerable listdata) {  
    foreach(object obj in listdata)   
        //logic to create xml  
}

… which you now can call with any IEnumerable, or write it the “modern” way as:

public string GetXML(IEnumerable<object> listdata) {  
    foreach(object obj in listdata)   
        //logic to create xml  
}

… which you can call with any IEnumerable via GetXML(someEnumerable.Cast<object>()) and in C# 4.0 even directly by covariance.

If you need the type of an element runtime, you can get it using .GetType() on each element, or you can just pass it in as a parameter (and provide an override for backwards-compatibility):

public string GetXML(Type elementType, IEnumerable<object> listdata) {  
    foreach(object obj in listdata)   
        //logic to create xml  
}

public string GetXML<T>(IEnumerable<T> listdata) {
    return GetXML(typeof(T),listdata.Cast<object>());
}

Incidentally, if you’re constructing XML, a string is probably a less robust return-type choice: if possible, you could work with something like an XElement instead – and get xml-validity guarantee’s to boot.