delphi: update project code (fixup before merging)

Co-authored-by: Nick Volynkin <nikolay.volynkin@devexpress.com>
Co-authored-by: Ilia Nenashev <ilia.nenashev@devexpress.com>

Author: NickVolynkin

Delphi/PDFReportGenerator.dpr

@@ -8,79 +8,80 @@ uses
   System.SysUtils,
   System.Classes,
   System.IniFiles,
-  dxBackend,
+  dxBackend,                     // DevExpress Reports and Dashboards backend
   dxBackend.Bundled,
   dxBackend.ConnectionString.SQL,
-  dxReport;
+  dxReport,                      // DevExpress Reports frontend
+  dxReport.Parameters; 
 
 procedure ExportReportToPdf;
 var
-  AManager: TdxBackendDataConnectionManager;
+  AConfig: TIniFile;
   AConnection: TdxBackendDatabaseSQLConnection;
   AReport: TdxReport;
-
+  AReportParameter: TdxReportParameter;
   AStream: TMemoryStream;
-
-  AIni: TIniFile;
-
-  AParamName: string;
-  AKeys: TStringList;
-  I: Integer;
 begin
-  TdxBackend.Instance.Start; // Start the backend
+  // Start the DevExpress backend.
+  TdxBackend.Instance.Start;
 
-  AManager := TdxBackendDataConnectionManager.Create(nil);
-  AIni := TIniFile.Create('..\PDFReportGenerator.ini');
+  // Read the configuration file.
+  AConfig := TIniFile.Create('..\PDFReportGenerator.ini');
   try
-    AConnection := TdxBackendDatabaseSQLConnection(AManager.DataConnections.
-      Add(TdxBackendDatabaseSQLConnection));
-
-    AConnection.DisplayName := AIni.ReadString('Connection', 'Name', '');
-    AConnection.ConnectionString :=
-      AIni.ReadString('Connection', 'ConnectionString', '');
-    AConnection.Active := True;
-
-    AReport := TdxReport.Create(nil);
+    // Create a database connection.
+    AConnection := TdxBackendDatabaseSQLConnection.Create(nil);
     try
-      AReport.Layout.LoadFromFile(AIni.ReadString('Report', 'LayoutFileName', ''));
-      AReport.ReportName := 'Report';
-
-      AReport.LoadParametersFromReport;
+      // Assign the name "MS SQL Connection" to the database connection.
+      // As part of this operation, the connection manager registers the connection and makes it available to reports.
+      AConnection.DisplayName := AConfig.ReadString('Connection', 'Name', '');
+      // Assign the specified connection string to the database connection.
+      AConnection.ConnectionString := AConfig.ReadString('Connection', 'ConnectionString', '');
 
-      AKeys := TStringList.Create;
+      // Create a new DevExpress Report.
+      AReport := TdxReport.Create(nil);
       try
-        for I := 0 to AKeys.Count - 1 do
-        begin
-          AParamName := AKeys[I];
+        // Assign a name to the newly created report.
+        AReport.ReportName := 'Report';
+        // Load report layout from a `.repx` layout file.
+        // Report layout contains visual elements and data bindings:
+        // - List of parameters used to filter data obtained from a database and displayed in the report.
+        // - Database connection name and SQL query to obtain data from a database.
+        AReport.Layout.LoadFromFile(AConfig.ReadString('Report', 'LayoutFileName', ''));
+        
+        // Read a list of parameter names from the layout file.
+        // (Presented layout file has a single parameter named `CategoryNameReportParameter`.)
+        AReport.LoadParametersFromReport;
 
-          if AReport.Parameters.ParamByName[AParamName] <> nil then
-            AReport.Parameters
-              .ParamByName[AKeys[I]]
-              .Value := AIni.ReadString('Parameters', AParamName, '');
-        end;
-      finally
-        AKeys.Free;
-      end;
+        // For each parameter, read and assign its value from the configuration file.
+        // Parameter values are used to filter data obtained from a database.
+        // The presented technique allows you to produce various reports by filtering data with parameters.
+        for AReportParameter in AReport.Parameters do
+          AReportParameter.Value := AConfig.ReadString('Parameters', AReportParameter.Name, '');
 
-      AStream := TMemoryStream.Create;
-      try
-        AReport.ExportToPDF(AStream);
-        AStream.SaveToFile(AIni.ReadString('Report', 'OutputFileName', ''))
+        // Create a memory stream to hold the exported PDF data.
+        AStream := TMemoryStream.Create;
+        try
+          // Export the report to PDF format and save it to the memory stream.
+          AReport.ExportToPDF(AStream);
+          // Write the content of the memory stream to an output file.
+          // The file name is specified in the configuration file.
+          AStream.SaveToFile(AConfig.ReadString('Report', 'OutputFileName', ''));
+        finally
+          AStream.Free;
+        end;
       finally
-        AStream.Free;
+        AReport.Free;
       end;
     finally
-      AReport.Free;
+      AConnection.Free;
     end;
   finally
-    AManager.Free;
-    AIni.Free;
+    AConfig.Free;
   end;
 end;
 
 begin
   try
-    { TODO -oUser -cConsole Main : Insert code here }
     ExportReportToPdf;
   except
     on E: Exception do