VST und ADO

[ucor]

Hallo,
seit einiger Zeit benutze ich Delphi und beschäftige mich zur Zeit mit dem VirtualStringTree.
Im Internet habe ich ein interresantes Beispiel gefunden, das mit dem ClientDataSet arbeitet.
Ich würde gern eine Accessdatenbankverbindung über AdoConnection und BetterADODataSet herstellen.
Das Problem liegt in der Methode FindKey, die nicht unterstützt wird. Mit Seek habe ich leider keinen
Erfolg gehabt. Ich poste mal den Sourcecode.

Code:

unit VTDBExample;

interface

   uses
      Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
      VirtualTrees, StdCtrls, ExtCtrls, Provider, DB, DBClient,
      Menus,  ImgList, Grids, DBGrids, ADODB, BetterADODataSet;
  type

      TBasicNode =
      class
         protected
         FCaption    : shortstring;
         FID         : longint;
         FImageIndex : longint;
         FHasChanged : boolean;

         public
         constructor Create( const sCaption : shortstring; const iID, iIndex: longint);

         property Caption     : shortstring  read FCaption     write FCaption;
         property ID          : longint      read FID          write FID;
         property ImageIndex  : longint      read FImageIndex  write FImageIndex;
         property HasChanged  : boolean      read FHasChanged  write FHasChanged;
      end;

      TBasicNodeAdd =
      class(TBasicNode)
         protected
         FJobTitle   : shortstring;
         FAdd1       : shortstring;
         FAdd2       : shortstring;
         FAdd3       : shortstring;
                                                               
         public
         property Add1 : shortstring  read FAdd1 write FAdd1;
         property Add2 : shortstring  read FAdd2 write FAdd2;
         property Add3 : shortstring  read FAdd3 write FAdd3;
         property JobTitle    : shortstring  read FJobTitle    write FJobTitle;
      end;             

      PTreeData = ^TTreeData;
      TTreeData = record
      FObject : TBasicNode;
      end;


   type
      TfrmVTDBExample =
      class(TForm)
         Label1: TLabel;
         cds: TClientDataSet;
         Panel1: TPanel;
         VT: TVirtualStringTree;
         imgMaster: TImageList;
         cds3: TBetterADODataSet;
         ADOConnection1: TADOConnection;
         
         procedure FormClose(Sender: TObject; var Action: TCloseAction);
         procedure VTGetText(Sender: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType;
         var Text: WideString);
         procedure VTFreeNode(Sender: TBaseVirtualTree; Node: PVirtualNode);
         procedure VTInitNode(Sender: TBaseVirtualTree; ParentNode, Node: PVirtualNode;
         var InitialStates: TVirtualNodeInitStates);
         procedure FormActivate(Sender: TObject);
         procedure VTGetImageIndex(Sender: TBaseVirtualTree;
         Node: PVirtualNode; Kind: TVTImageKind; Column: TColumnIndex;
         var Ghosted: Boolean; var ImageIndex: Integer);
         procedure VTCompareNodes(Sender: TBaseVirtualTree; Node1,
         Node2: PVirtualNode; Column: TColumnIndex; var Result: Integer);
         procedure VTGetNodeDataSize(Sender: TBaseVirtualTree; var NodeDataSize: Integer);
         procedure VTInitChildren(Sender: TBaseVirtualTree; Node: PVirtualNode; var ChildCount: Cardinal);


         private
         procedure LoadCDS;

      end;
   
implementation
{$R *.DFM}

constructor TBasicNode.Create( const sCaption : shortstring; const iID, iIndex: longint);
   begin
      inherited Create;
      FCaption    := sCaption;
      FID         := iID;
      FImageIndex := iIndex;
   end;

   const
      FLDN_CustNo             = 0;
      FLDN_Company            = 1;
      FLDN_Addr1              = 2;
      FLDN_Addr2              = 3;
      FLDN_City               = 4;
      FLDN_State              = 5;
      FLDN_Zip                = 6;
      FLDN_Country            = 7;
      FLDN_Phone              = 8;
      FLDN_FAX                = 9;
      FLDN_TaxRate            = 10;
      FLDN_Contact            = 11;
      FLDN_LastInvoiceDate    = 12;

   procedure TfrmVTDBExample.FormActivate(Sender: TObject);
   var
      r  : TRect;
   begin
      SystemParametersInfo(SPI_GETWORKAREA, 0, @r, 0);
      Height := r.Bottom-Top;
      Width  := r.Right-Left;
      Application.ProcessMessages;
      LoadCDS;
   end;

   procedure TfrmVTDBExample.FormClose(Sender: TObject; var Action: TCloseAction);
   begin
      Action := caFree;
   end;

   procedure TfrmVTDBExample.LoadCDS;
   var
      Node  : PVirtualNode;
   begin
      with cds do
      begin
         VT.BeginUpdate;
         try
            FileName := 'customer.cds';
            Active := True;
            IndexFieldNames := 'CustNo';
             while not eof do
                begin
                  Node := VT.AddChild(nil);
                  VT.ValidateNode( Node, False );
                  Next;
                end;
         finally
            VT.EndUpdate;
         end;
      end;
   end;

   procedure TfrmVTDBExample.VTGetNodeDataSize(Sender: TBaseVirtualTree;  var NodeDataSize: Integer);
   begin
      NodeDataSize := SizeOf(TTreeData);
   end;

   procedure TfrmVTDBExample.VTInitNode(Sender: TBaseVirtualTree; ParentNode, Node: PVirtualNode;
             var InitialStates: TVirtualNodeInitStates);
   var
      Data     : PTreeData;
      iImage   : integer;
   begin
      Data := Sender.GetNodeData(Node);
      iImage   := -1;
      if Sender.GetNodeLevel( Node ) = 0 then
      begin
         iImage   := 3;
         if (Node.Index < 10) then
         begin
            iImage   := 31;
            InitialStates := InitialStates + [ivsHasChildren];
         end;
      end;   
      Data.FObject := TBasicNodeAdd.Create( cds.Fields[FLDN_Company].AsString, cds.Fields[FLDN_CustNo].AsInteger, iImage );
   end;                                                                            

   procedure TfrmVTDBExample.VTInitChildren(Sender: TBaseVirtualTree; Node: PVirtualNode; var ChildCount: Cardinal);
   begin
      ChildCount := 1;
   end;
   
   procedure TfrmVTDBExample.VTFreeNode(Sender: TBaseVirtualTree; Node: PVirtualNode);
   var
      Data: PTreeData;
   begin
      Data := Sender.GetNodeData(Node);
      Data.FObject.Free;
      Finalize( Data^ );
   end;

Hier die entscheidende Procedure

Code:

   
   procedure TfrmVTDBExample.VTGetText(Sender: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType; var Text: WideString);
   var
      Data     : PTreeData;
      FObject  : TBasicNodeAdd;
      iLevel   : integer;
   begin
      Text  := '';
      Data  := Sender.GetNodeData(Node);
      if Assigned(Data) and (Data.FObject <> nil) then with Data.FObject do
      begin
         iLevel := Sender.GetNodeLevel( Node );

         case Column of
         0:
            begin
               case TextType of
                  ttNormal:
                  begin
                     if iLevel = 0 then
                        begin
                           Text:=Caption
                        end
                     else
                       begin
                         if cds.FindKey([ID]) then with cds do
                           Text     := Trim( Fields[ FLDN_Addr1   ].AsString + ' ' +
                                       Fields[ FLDN_Addr2   ].AsString + ' ' +
                                       Fields[ FLDN_City    ].AsString + ' ' +
                                       Fields[ FLDN_State   ].AsString + ' ' +
                                       Fields[ FLDN_Zip     ].AsString + ' ' +
                                       Fields[ FLDN_Country ].AsString );
                       end;
                  end;
                  ttStatic:
                  begin
                     Text := '';
                  end;
               end;
            end;

            1:
            begin
               FObject := TBasicNodeAdd( Data.FObject );
               case TextType of
                  ttNormal:
                  begin
                     if (iLevel = 0)and cds.FindKey([ID])
                      then with cds do
                        Text := Fields[ FLDN_Contact ].AsString;
                  end;
               end;
            end;   

            2:
            begin
               if TextType = ttNormal then
                  Text := ' ';
            end;

         end;   
      end;
   end;

Code:

   procedure TfrmVTDBExample.VTGetImageIndex(Sender: TBaseVirtualTree; Node: PVirtualNode; Kind: TVTImageKind;
               Column: TColumnIndex; var Ghosted: Boolean; var ImageIndex: Integer);
   var
      Data  : PTreeData;
      iLevel: integer;
   begin
      ImageIndex := -1;
      Data  := Sender.GetNodeData(Node);
      iLevel:= Sender.GetNodeLevel( Node );

      if (Column = 2 ) then
      begin
         if ( Kind in [ ikNormal, ikSelected ] ) and (iLevel=0) then
            ImageIndex := 20
      end   
      else if Assigned(Data) and (Data.FObject <> nil) and (Column = 0) then
         ImageIndex := Data.FObject.ImageIndex;
   end;



   procedure TfrmVTDBExample.VTCompareNodes(Sender: TBaseVirtualTree; Node1,
     Node2: PVirtualNode; Column: TColumnIndex; var Result: Integer);
   var
      Data1  : PTreeData;
      Data2  : PTreeData;
   begin
      Data1 := Sender.GetNodeData(Node1);
      Data2 := Sender.GetNodeData(Node2);

      case Column of
         0: Result := CompareText( Data1.FObject.Caption, Data2.FObject.Caption )
      end;
   end;

end.