Activator.CreateInstance problem

[Guest]

Hi all, when trying to load and create an instance from an assembly I'm getting InvalidCastException. Here's a chunk of code

Assembly cAssembly = Assembly.LoadFrom("d:\\DAOTest.dll")
object cDAOInstance = null
foreach (Type cType in cAssembly.GetTypes()

if ((cType.IsClass == true) && (cType.FullName == "DAOTest.CustomerRowSet")

cDAOInstance = Activator.CreateInstance(cType)

// this line generates the InvalidCastExceptio
//((DAOTest.CustomerRowSet)cDAOInstance).getTraderList()

CustomerRowSet rs = new CustomerRowSet()
Type t1 = cDAOInstance.GetType()
Type t2 = rs.GetType()
Console.WriteLine(t1.ToString())
Console.WriteLine(t2.ToString())



Strangely, the result in the console for the ToString calls is

DAOTest.CustomerRowSe
DAOTest.CustomerRowSe

Any info/advice on resolving this problem ? Many thanks in advance

Chris

 

[Ian Frawley]

Hi,

Is it possible that when you try to cast to (DAOTest.CustomerRowSet) the
compiler doesn't know what one of these is so it bombs.

Ian

Hi all, when trying to load and create an instance from an assembly I'm

getting InvalidCastException. Here's a chunk of code:

 

[Guest]

Not sure... possibly. I can create an instance of CustomerRowSet which resides in DAOTest so I would assume, possibly invalidly, that the assembly (DAOTest) and the class (CustomerRowSet) is in scope

 

[Ian Frawley]

Just out of interest does this line:

--> //((DAOTest.CustomerRowSet)cDAOInstance).getTraderList();

Return anything?

Not sure... possibly. I can create an instance of CustomerRowSet which

resides in DAOTest so I would assume, possibly invalidly, that the assembly
(DAOTest) and the class (CustomerRowSet) is in scope.

 

[Guest]

Currently it's a void function which simply makes a Console WriteLine call.

 

[Ian Frawley]

I might be misreading this somewhere and if I am the I appologise but if
Console.WriteLine(t1.ToString()); Prints DAOTest.CustomerRowSet
Then can you not just go:

cDAOInstance.getTraderList();

Ian

 

[Guest]

Just checked, to be on the safe side, doesn't compile as cDAOInstance is of type object

 

[Ian Frawley]

It looks like you are having a similar problem to me. Have you debugged your
code to see if cDAOInstanceis actually an instance of something and not
undefined.

 

[Guest]

When debugging the cDAOInstance variable (type object) shows as being of typ
DAOTest.CustomerRowSet. To clarify, CustomerRowSet is an extension o
RowSet (one of my classes) which is an extension of BaseDAO (again, one of mine
which is an extension of DataTable (.NET class). I'm checking if this has an
relevance on the problem by creating a simple class heirarchy which doesn'
chain from DataTable

 

[Ian Frawley]

Try this:

Assembly cAssembly = Assembly.LoadFrom("d:\\DAOTest.dll");
foreach (Type cType in cAssembly.GetTypes())
{
if ((cType.IsClass == true) && (cType.FullName ==
"DAOTest.CustomerRowSet"))
{
DAOTest.CustomerRowSet cDAOInstance =
(DAOTest.CustomerRowSet)Activator.CreateInstance(cType);

cDAOInstance.getTraderList();
}
}

Regards

Ian

 

[Guest]

Ian, that worked a treat. Thank you very much. Just have to figure out how I
cast to the dynamic type in my generic class loader now

Thanks again.

 

[Ian Frawley]

No probs Chris.

Ian