TdxBackendParameterValue Class

A parameter value.

Declaration

TdxBackendParameterValue = class(
    TCollectionItem
)

Remarks

Each parameter is stored as a Variant value accessible through the Value property.

You can use the parent parameter’s DataType property to switch between supported parameter value types (that is, Variant value interpretation options). Different data types use different editor types in the Parameters panel in the UI.

Direct TdxBackendParameterValue Class Reference

The following public API members reference a TdxBackendParameterValue object:

TdxBackendParameterValues.Add

Creates a new parameter value and adds it to the collection.

TdxBackendParameterValues.Items

Provides indexed access to all parameter values stored in the collection.

Code Examples

The following code snippets use the DataType property to ensure that the expected String type is defined for the orderID parameter and assigns a string value to it.

Note

The DataType property is common to report and dashboard parameters. These examples perform the same type check and value assignment but use component-specific APIs.

Check Report Parameter Type

Delphi

uses
  dxReport.Control,       // Declares the TdxReportControl class
  dxReport.Parameters,    // Declares the TdxReportParameter class
  dxBackend.Parameters;   // Declares the TdxBackendParameterDataType enum
  System.SysUtils;        // Declares exception classes

procedure TOrderReportForm.InitReport(const AOrderID: string);
var
  AParameter: TdxReportParameter;
begin
  // Find the report parameter with the specified name
  AParameter := dxReportControl1.Parameters.FindParam('orderID');
  // Check if the parameter exists and has the String type
  if (AParameter = nil) or (AParameter.DataType <> TdxBackendParameterDataType.rptString) then
    raise Exception.Create('Missing the required parameter "orderID" of type "String".');
  AParameter.Value := AOrderID;
end;

C++

#include "dxReport.Control.hpp"       // Declares the TdxReportControl class
#include "dxReport.Parameters.hpp"    // Declares the TdxReportParameter class
#include "dxBackend.Parameters.hpp"   // Declares the TdxBackendParameterDataType enum
#include <System.SysUtils.hpp>        // Declares exception classes

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

void __fastcall TOrderReportForm::InitReport(const UnicodeString &AOrderID) {
  // Find the report parameter with the specified name
  TdxReportParameter* AParameter = dxReportControl1->Parameters->FindParam(L"orderID");
  // Check if the parameter exists and has the String type
  if ((AParameter == nullptr) || (AParameter->DataType != TdxBackendParameterDataType::rptString))
    throw Exception(L"Missing the required parameter \"orderID\" of type \"String\".");
  AParameter->Value = AOrderID;
}

Check Dashboard Parameter Type

Delphi

uses
  dxDashboard.Control,      // Declares the TdxDashboardControl class
  dxDashboard.Parameters,   // Declares the TdxDashboardParameter class
  dxBackend.Parameters;     // Declares the TdxBackendParameterDataType enum
  System.SysUtils;        // Declares exception classes

procedure TDashboardForm.InitDashboard(const AOrderID: string);
var
  AParameter: TdxDashboardParameter;
begin
  // Find the dashboard parameter with the specified name
  AParameter := dxDashboardControl1.Parameters.FindParam('orderID');
  // Check if the parameter exists and has the String type
  if (AParameter = nil) or (AParameter.DataType <> TdxBackendParameterDataType.rptString) then
    raise Exception.Create('Missing the required parameter "orderID" of type "String".');
  AParameter.Value := AOrderID;
end;

C++

#include "dxDashboard.Control.hpp"      // Declares the TdxDashboardControl class
#include "dxDashboard.Parameters.hpp"   // Declares the TdxDashboardParameter class
#include "dxBackend.Parameters.hpp"     // Declares the TdxBackendParameterDataType enum
#include <System.SysUtils.hpp>        // Declares exception classes

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

void __fastcall TDashboardForm::InitDashboard(const UnicodeString &AOrderID) {
  // Find the dashboard parameter with the specified name
  TdxDashboardParameter* AParameter = dxDashboardControl1->Parameters->FindParam(L"orderID");
  // Check if the parameter exists and has the String type
  if ((AParameter == nullptr) || (AParameter->DataType != TdxBackendParameterDataType::rptString))
    throw Exception(L"Missing the required parameter \"orderID\" of type \"String\".");
  AParameter->Value = AOrderID;
}

Inheritance

TObject

TPersistent

TCollectionItem

TdxBackendParameterValue