[SOLVED} Virtual Strint Tree Load Error

[Pe3s]

Hello, I have a code that saves and loads data into a Virtual String Tree, I have a question why the code causes an access violation error with more than 2 columns

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button2Click(Sender: TObject);
2. var
3.   FS: TStream;
4.   CNT, I: Integer;
5.   Node: PVirtualNode;
6.   Data: PData;
7. begin
8.   VST.Clear;
9.   FS := TFileStream.Create(Application.Location + 'baza.vst', fmOpenRead or fmShareDenyNone);
10.   try
11.     CNT := FS.ReadWord;
12.     if CNT > 0 then
13.     begin
14.       I := 1;
15.       while I <= CNT do
16.       begin
17.         Node := VST.AddChild(nil);
18.         Data := VST.GetNodeData(Node);
19.         FS.Read(Data^, SizeOf(TData) -2*SizeOf(String));
20.         Data^.Imie := FS.ReadAnsiString;
21.         Data^.Nazwisko := FS.ReadAnsiString;
22.         Inc(I);
23.       end;
24.     end;
25.   finally
26.     FS.Free;
27.   end;
28. end;
29.  
30. procedure TForm1.Button3Click(Sender: TObject);
31. var
32.   FS: TStream;
33.   Node: PVirtualNode;
34.   Data: PData;
35. begin
36.   FS := TFileStream.Create(Application.Location + 'baza.vst', fmCreate or fmShareDenyWrite);
37.   try
38.     FS.WriteWord(VST.RootNodeCount);
39.     Node := VST.GetFirst;
40.     while Assigned(Node) do
41.   begin
42.     Data := VST.GetNodeData(Node);
43.     FS.Write(Data^, SizeOf(TData) -2*SizeOf(String));
44.     FS.WriteAnsiString(Data^.Imie);
45.     FS.WriteAnsiString(Data^.Nazwisko);
46.     Node := VST.GetNext(Node);
47.   end;
48.   finally
49.     FS.Free;
50.   end;
51. end;
52.  

[Ericktux]

Hello friend, I currently use this code, I hope it helps you.

Code: Pascal  [Select][+][-]

1. procedure TForm1.VSTGetNodeDataSize(Sender: TBaseVirtualTree;
2.   var NodeDataSize: Integer);
3. begin
4.   NodeDataSize := SizeOf(TData);  // important to put if error exception appears
5. end;
6.  
7. procedure TForm1.VSTLoadNode(Sender: TBaseVirtualTree; Node: PVirtualNode;
8.   Stream: TStream);
9.   var
10.     Data: Pdata;
11.     Len: Integer;
12.   begin
13.     Data := VST.GetNodeData(Node);
14.     //NewNode:=Sender.GetNodeData(Node);
15.  
16.         Stream.Read(Len, SizeOf(Len));
17.   SetLength(Data^.Fnombre, Len);
18.   Stream.Read(PChar(Data^.Fnombre)^, Len * SizeOf(Data^.Fnombre[1]));
19.  
20.       Stream.Read(Len, SizeOf(Len));
21.   SetLength(Data^.Fapellido, Len);
22.   Stream.Read(PChar(Data^.Fapellido)^, Len * SizeOf(Data^.Fapellido[1]));
23.  
24.       Stream.Read(Len, SizeOf(Len));
25.   SetLength(Data^.Fedad, Len);
26.   Stream.Read(PChar(Data^.Fedad)^, Len * SizeOf(Data^.Fedad[1]));
27.  
28.       Stream.Read(Len, SizeOf(Len));
29.   SetLength(Data^.Ftrabajando, Len);
30.   Stream.Read(PChar(Data^.Ftrabajando)^, Len * SizeOf(Data^.Ftrabajando[1]));
31.  
32.      //FImageIndex
33.    //Stream.Read(PChar(Data^.FImageIndex)^, SizeOf(Data^.FImageIndex));
34.  
35.      // load cImageIndex
36.   Stream.Read(Data^.FImageIndex, SizeOf(Data^.FImageIndex));
37.   end;
38.  
39. procedure TForm1.VSTSaveNode(Sender: TBaseVirtualTree; Node: PVirtualNode;
40.   Stream: TStream);
41.   var
42.      data: Pdata;
43.      len: Integer;
44.   begin
45.   Data := VST.GetNodeData(Node);
46.  
47. Len := Length(Data^.Fnombre);
48. Stream.Write(Len, SizeOf(Len));
49. Stream.Write(PChar(Data^.Fnombre)^, Length(Data^.Fnombre) * SizeOf(Data^.Fnombre[1]));
50.  
51. Len := Length(Data^.Fapellido);
52. Stream.Write(Len, SizeOf(Len));
53. Stream.Write(PChar(Data^.Fapellido)^, Length(Data^.Fapellido) * SizeOf(Data^.Fapellido[1]));
54.  
55. Len := Length(Data^.Fedad);
56. Stream.Write(Len, SizeOf(Len));
57. Stream.Write(PChar(Data^.Fedad)^, Length(Data^.Fedad) * SizeOf(Data^.Fedad[1]));
58.  
59. Len := Length(Data^.Ftrabajando);
60. Stream.Write(Len, SizeOf(Len));
61. Stream.Write(PChar(Data^.Ftrabajando)^, Length(Data^.Ftrabajando) * SizeOf(Data^.Ftrabajando[1]));
62.  
63. //FImageIndex
64. //Stream.Write(Data^.FImageIndex, SizeOf(Data^.FImageIndex));
65. //Stream.Write(Data^.FImageIndex, SizeOf(Data^.FImageIndex));
66.  
67. // store cImageIndex
68.   Stream.Write(Data^.FImageIndex, SizeOf(Data^.FImageIndex));
69.   end;
70.  
71. procedure TForm1.Button2Click(Sender: TObject);  // botón para guardar
72. begin
73.   VST.SaveToFile('filename.dat');
74.  
75. end;
76.  
77. procedure TForm1.Button3Click(Sender: TObject);  // botón para abrir
78. begin
79.   VST.LoadFromFile('filename.dat');
80. end;

[Pe3s]

@Ericktux Thank you friend, I will check

[Pe3s]

@Ericktux The code works, I can ask for read and write hints of such types as Integer, float, TTime