Using Reporting Services GetReportParameters web method

A question today on how to get the valid values for a report parameter via the web service API when a query specifies the valid values. (Whew - clunky sentence).

To do this you can use the GetReportParameters web method. First, be wary of a small bug in the documentation where the order of parameters are incorrect. Not a big problem with intellisense, though.

Example:

ReportingService rService = new ReportingService();
rService.Credentials = 
            System.Net.CredentialCache.DefaultCredentials;
 
string historyID = null;
bool forRendering = true;
ParameterValue[] values = null;                                  
DataSourceCredentials[] credentials = null;
ReportParameter[] parameters;
 
parameters = rService.GetReportParameters
            (
                        "/Northwind Reports/Report2",
                        historyID,
                        forRendering,
                        values,
                        credentials                                           
            );

This will give you back an array of ReportParameter objects. If a ReportParameter object has a set of valid values defined by a query, reporting services will run the query and populate the ValidValues property with ValidValue objects (only when ForRendering == true). If we wanted to dump the valid values for parameter[0]:

foreach(ValidValue v in parameters[0].ValidValues)
{
    Console.WriteLine(v.Label + " " + v.Value);
}

Note, if you have hierarchical parameters, where, for example, the set of valid values for parameters[1] depends on the value selected for parameters[0], you’ll need to initialize the ParameterValue array to get the valid values for parameters[1]. If you are doing this all from scratch this may mean multiple calls to GetReportParameters.