| title | description | author | ms.author | ms.date | ms.service | ms.subservice | ms.topic | ms.custom | helpviewer_keywords | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Implementing a Command Class for a Data Processing Extension |
Learn how to implement a Command class for a data processing extension so that the extension can formulate requests and pass them on to the data source. |
maggiesMSFT |
maggies |
03/06/2017 |
reporting-services |
extensions |
reference |
updatefrequency5 |
|
The Command object formulates a request and passes it on to the data source. The command text can take many different syntactical forms, including text and XML. If results are returned, the Command object returns results as a DataReader object.
To create a Command class, implement xref:Microsoft.ReportingServices.DataProcessing.IDbCommand. Implement the xref:Microsoft.ReportingServices.DataProcessing.IDbCommand.ExecuteReader%2A method to return a result set as a DataReader object. The xref:Microsoft.ReportingServices.DataProcessing.IDbCommand.ExecuteReader%2A method of your Command class should include an implementation that takes a xref:Microsoft.ReportingServices.DataProcessing.CommandBehavior enumeration as an argument. If you deploy your data processing extension to Report Designer, provide an implementation that handles a xref:Microsoft.ReportingServices.DataProcessing.CommandBehavior.SchemaOnly case in the xref:Microsoft.ReportingServices.DataProcessing.IDbCommand.ExecuteReader%2A method. A schema-only implementation is used to supply Report Designer with a fields list. The DataReader object returned by the xref:Microsoft.ReportingServices.DataProcessing.IDbCommand.ExecuteReader%2A method needs to contain type and name information for the fields, or columns, in your result set.
Optionally, your Command class can implement xref:Microsoft.ReportingServices.DataProcessing.IDbCommandAnalysis. This interface enables an implementing class to analyze a query and return a list of parameters in the query. The functionality of the xref:Microsoft.ReportingServices.DataProcessing.IDbCommandAnalysis interface is only used in Report Designer. When you implement xref:Microsoft.ReportingServices.DataProcessing.IDbCommandAnalysis, you enable users of Report Designer to be prompted for parameters whenever a report is run in preview mode. In addition, you can view the parameters in the Parameters tab of the Data Set dialog.
Note
You should not implement xref:Microsoft.ReportingServices.DataProcessing.IDbCommandAnalysis if your custom data processing extension does not support parameters.
For a sample Command class implementation, see SQL Server Reporting Services Product Samples.
Reporting Services Extensions
Implementing a Data Processing Extension
Reporting Services Extension Library