TdxReportParameter Class

A report parameter.

Declaration

TdxReportParameter = class(
    TdxBackendCustomParameter
)

Remarks

Report parameters allow you and your end users to filter report data dynamically. You can define a parameter and reference it in a report’s query, filter criteria, or expressions (including calculated fields) at runtime instead of hard-coded values.

A TdxReportParameter object implements an individual parameter within a report’s Parameters collection.

API Members

The following members allow you to configure report parameters:

AllowNull

Specifies whether Null can be assigned as the dashboard parameter value.

DataType

Returns the parameter data type.

Description

Returns the parameter label displayed in the UI.

Enabled

Specifies if users can change the parameter value in the UI.

IsMultiValueParameter

Indicates if the parameter has multiple values.

IsRangeParameter

Indicates whether the parameter defines a date/time range.

Name

Returns the unique parameter identifier.

Value | Values

Specify the default parameter value.

Visible

Specifies whether the parameter editor is visible in the UI.

Code Example: List Report Parameters

Delphi

uses
  dxReport.Control,      // Declares the TdxReportControl class
  dxReport.Parameters,   // Declares the TdxReportParameter class
  dxMessageDialog,       // Declares the TdxMessageDialogForm class
  System.StrUtils;       // Provides advanced string management routines

procedure TForm1.cxButton1Click(Sender: TObject);
var
  AList: TStringList;
  AParameter: TdxReportParameter;
begin
  // Create a TStringList instance
  AList := TStringList.Create;
  try
    // Iterate through report parameters
    for AParameter in dxReportControl1.Parameters do
      AList.Add(Format('- %s', [
        // Use the parameter Name if Description is missing
        IfThen(AParameter.Description <> '', AParameter.Description, AParameter.Name)
      ]));
    // Display the parameter list or a notification message if the list is empty
    if AList.Count > 0 then
      dxShowMessage(AList.Text)
    else
      dxShowMessage('The report has no parameters.');
  finally
    AList.Free;
  end;
end;

C++

#include "dxReport.Control.hpp"      // Declares the TdxReportControl class
#include "dxReport.Parameters.hpp"   // Declares the TdxReportParameter class
#include "dxMessageDialog.hpp"       // Declares the TdxMessageDialogForm class

// Add the following linker directives to the corresponding CPP source file:
#pragma link "dxReport.Control"   // Required to use dxReport.Control.hpp declarations

void __fastcall TForm1::cxButton1Click(TObject* Sender) {
  TStringList* AList = new TStringList();
  try {
    // Iterate through report parameters
    for (int i = 0; i < dxReportControl1->Parameters->Count; i++) {
      TdxReportParameter* AParameter = dxReportControl1->Parameters->Items[i];
      UnicodeString ALabel;
      // Use the parameter Name if Description is missing
      if (AParameter->Description.IsEmpty())
        ALabel = AParameter->Name;
      else
        ALabel = AParameter->Description;
      AList->Add(Format(L"- %s", ARRAYOFCONST((ALabel))));
    }
    // Display the parameter list or a notification message if the list is empty
    if (AList->Count > 0)
      dxShowMessage(AList->Text);
    else
      dxShowMessage(L"The report has no parameters.");
  }
  __finally {
    delete AList;
  }
}

Direct TdxReportParameter Class References

The following public API members reference a TdxReportParameter object:

TdxReportParameters.FindParam

Returns the stored parameter with the specified name.

TdxReportParameters.Items

Provides indexed access to all parameters stored in the collection.

TdxReportParameters.ParamByName

Returns the stored parameter with the specified name.

Inheritance

TObject

TPersistent

TCollectionItem

TdxBackendCustomParameter

TdxReportParameter