[dba-VB] C#: Raising events

I got lost in the middle, John, but did you add a handler for the class object event to the object where you're sinking the event?

Charlotte Foust 

-----Original Message-----
From: dba-vb-bounces at databaseadvisors.com [mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of jwcolby
Sent: Monday, January 25, 2010 8:50 AM
To: VBA
Subject: [dba-VB] C#: Raising events

Silly me, I thought that events would be easy in C#.  I guess once you figure them out they probably
are, but coming from VBA where all the behind the scenes stuff is done for you, it is kinda confusing.

What I want to do is execute stored procedures, and publish status information about each SP
executed on my form starts a process running.

I have a class which encapsulates my stored procedure stuff for creating the command object,
capturing the parameters and eventually executing the stored procedure.

I assume that this object might raise an event when the stored procedure returns i.e.
sCmd.ExecuteNonQuery() returns control to C# ?

OTOH, I have other classes which USE the SP class.  These are the classes that actually call
specific stored procedures, pass parameters, and control the program flow depending on whether the
called SP succeeds or fails etc.  THESE classes should raise an event, sunk on the form, which
passes up the SP class instance just executed, IOW I just executed a "Create index" stored procedure
and want to display on the form the name of the sp and whether it completed satisfactorily, how long
it took and so forth.

I am going to go with the classes which execute sequences of SPs being the class that raises the
event.  I am looking at this as an example:

http://www.codeproject.com/KB/cs/csevents01.aspx

clsStoredProc creates the command object, packages the parameters, and executes the stored procedure.

clsAZExport uses a sequence of stored procedures to perform an export process.

So... I create an event delegate definition which defines the event I will raise.  Where do I place
this?  For the moment I have placed it inside of the container where clsStoredProc is defined.

I now have to create evargStoredProcedure - a public class for the argument that this event will
pass up to the form.  The argument is going to be the current instance of the clsStoredProc.  Where
is this class created?  Do I just define a new class at the project level for this event argument.
It seems that it is part and parcel of using clsStoredProcedure (which is in its own project) so
placing it in the code container for that class seems appropriate.  For the moment I have placed it
inside of the container where clsStoredProc is defined.


Now, in every method of clsAZExport I add two lines:

	evargStoredProcedure svargSP = new evargStoredProcedure(sp);
	evStoredProc(this, svargSP);

This apparently creates the arguments object and then raises the event.

Man oh man, is this a PITA (after VBA).  I haven't even begun to sink the event yet.

So... back in the form which uses clsAZExport to export data from SQL Server...

At this point their example breaks down entirely.  I am not writing to the debug window, I am trying 
to write to a control on a form.  While the debug window can be written to from anywhere, a control 
on a specific form is decidedly specific.  Thus the form has to somehow sink the evStoredProc.

And I grind to a halt, unable to figure out what to do next.  It seems that my clsAZExport declared 
in the form has an event evStoredProc, and that I need to wire that.  I kind of figured that once I 
did all this I would click on any object that raises an event and I would see a list of their 
events, but I do not, or I do not know how to see them.  As an example if I have a text box, it has 
events.  If I click on that I can see its events, select one and voila, a place to say what to do. 
How do I do that for an event raised by my class dimensioned and used in my form?

If anyone is following this and knows what I am trying to do and what to do next, please speak up.

-- 
John W. Colby
www.ColbyConsulting.com

_______________________________________________
dba-VB mailing list
dba-VB at databaseadvisors.com
http://databaseadvisors.com/mailman/listinfo/dba-vb
http://www.databaseadvisors.com