Extracting Parameter values from a Custom Data Processing Extension

I've created a custom Data Processing Extension and I've implemented the IDBCommandAnalysis interface so that my reports can enter parameters and pass them to my Data Processing Extension.

My question is, how do I extract the value from the Parameters coming from the report? Where do the parameters get passed off from the report? I can query the Parameters collection and my report gets prompted in Preview mode to enter something for the parameter but I can't find the spot where it gets passed for processing.

The IDBCommand interface contains a method CreateParameter(...).

For every query parameter, RS will call CreateParameter to add the parameter to the Parameters collection.

See also: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/RSPROG/htm/rsp_ref_clr_dataproc_2a4a.asp

-- Robert

|||Where is the proper place to initialize the Parameter collection? I keep getting a "Collection was modified" when I try to tell my Command object was parameters it has.
|||

Robert Bruckner MSFT wrote:

For every query parameter, RS will call CreateParameter to add the parameter to the Parameters collection.

Sorry for pullig out this old thread, but it's exactly the problem I have right now.
At the moment my CreateParameter()-Function looks like this (like in the FSI example)

Code Snippet

Return CType(New DataParameter, IDataParameter)

nothing more. As an extra, I am searching for parameters everytime the command-text is set. I am pullig out the parameters from the text with a regExp and add them to the collection.
Is this the right way?

In technet it says: "The CreateParameter method is called by the report server to set the name and value for each query parameter in the command text. The parameter is then added to the Parameters collection prior to the ExecuteReader method being called."

Right now, I am doing all of that in my cde manually:
set command-text? then get parameters from string -> add all of them to the collection.

without this extra-step after setting the command-text, the collection gets called later and would be empty. There is no call from report-server to CreateParameter. (I put traces in every function/sub)
|||Ok, I worked it out:

"Public ReadOnly Property Parameters() As IDataParameterCollection Implements IDbCommand.Parameters"
This one is used by the server to access and build up the parameterCollection.

"Public Function GetParameters() As IDataParameterCollection Implements IDbCommandAnalysis.GetParameters"
This one has to parse out all parameters from the query, so the dataset preview can list them.
http://technet.microsoft.com/en-us/library/aa256673(SQL.80).aspx