Solved

Delete a Treeview node

Posted on 2009-07-14
4
324 Views
Last Modified: 2012-05-07
Dear Experts,

I have made a little programm that has a Treeview, a RichEdit.
and 4 buttons on a Panel. 2 buttons are for loading and saving
the treeview nodes with its associating text on the RichtEdit
to a database. The other 2 buttons are for creating a Folder-node
and a File-node in the Treeview. Everything works perfect.

Now I want to make a fifth button on the panel for deleting
a Treeview node. Who can help me with this procedure:

procedure TItem.Delete;
begin
//
end;

I have put the example on my site:
http://members.home.nl/peterkiers/
You see a floppy disc.

I also found this! I dont know if its usable:

procedure TForm1.TreeView1Deletion(Sender: TObject; Node: TTreeNode);
begin
  if node.Data<>nil then
  begin
    TItem(node.data).free;
    node.data:=nil;
  end;
end;

Greetings, Peter Kiers
0
Comment
Question by:peterkiers
  • 3
4 Comments
 
LVL 18

Accepted Solution

by:
Johnjces earned 500 total points
ID: 24850830
Same as previous post just use

TreeView1.Items[X].Delete;
0
 
LVL 1

Author Comment

by:peterkiers
ID: 24850905
In the example I have a treeview build from TObject called TItem
My question was, what to put in the TItem.Delete procedure
and what to put in the procedure of the Delete-button.
0
 
LVL 1

Author Comment

by:peterkiers
ID: 24857542
I have this procedure for deleting a file-node or a folder node.
And it works perfect:

procedure TForm1.DeleteItemClick(Sender: TObject);
var
   node : TTreeNode;
   mess, str : string;
   key_stat : integer;
begin
    Node := Treeview.Selected;
    if Assigned(Node) then
       begin
       str := Node.Text;
       mess := 'Are you sure that you want to delete the';
       Case Node.Level of
         0 : mess := mess + ' folder : ' +#13+#13 + str + '   ???' +#13+
                    'All folders, subfolders, items and subitems' +#13+ 'will be permanently deleted !!' +#13;
         1 : mess := mess + ' item : ' +#13+#13 + str + '   ???' + #13;
       end;
       with Application do
         begin
         NormalizeTopMosts;
         key_stat := MessageBox(pchar(mess), '         Confirmation', MB_YESNO);
         RestoreTopMosts;
       end;
       if key_stat = 7 then  Exit;         // 6 - YES ; 7 - N0
       TreeView.Items.Delete(Treeview.Selected);
       end
    else ShowMessage('Select a folder in the treeview first.');
end;

ACCEPT for one thing: The deleted node is still available in the database!!!
And it should be erased too. That's because the DeleteItemClick should call
for this procedure:

procedure TItem.Delete;
begin
//
end;

Greetings, Peter Kiers
0
 
LVL 1

Author Comment

by:peterkiers
ID: 24860666
I guess no one will download the example. So i have put the code in the code-section.

unit Unit1;
 

interface
 

uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, DB, ADODB, ComCtrls, StdCtrls, ImgList, ExtCtrls;
 

type

  TForm1 = class(TForm)

    TreeView1: TTreeView;

    Splitter1: TSplitter;

    Panel1: TPanel;

    Button1: TButton;

    Button2: TButton;

    ADOQuery1: TADOQuery;

    ADOConnection1: TADOConnection;

    FolderBtn: TButton;

    FileBtn: TButton;

    ImageList1: TImageList;

    RichEdit1: TRichEdit;

    Button3: TButton;

    procedure Button3Click(Sender: TObject);

    procedure RichEdit1KeyUp(Sender: TObject; var Key: Word;

      Shift: TShiftState);

    procedure FolderBtnClick(Sender: TObject);

    procedure FileBtnClick(Sender: TObject);

    procedure TreeView1Change(Sender: TObject; Node: TTreeNode);

    procedure FormCreate(Sender: TObject);

    procedure Button2Click(Sender: TObject);

    procedure Button1Click(Sender: TObject);

    

  private

    { Private declarations }

    procedure savetree(t: ttreeview);

    procedure loadtree(t: TTreeView);

    procedure saveNode(n: TTreeNode);

    function findNode(t:TTreeView; id: integer): TTreeNode;

    procedure AddItem(aText: string; aIndex: Integer; aParent: TTreeNode);

  public

    { Public declarations }

  end;
 

var

  Form1: TForm1;
 

implementation
 

{$R *.dfm}
 

type

  TItem = class(TObject)

  private

    fStatus: byte;

    fParentID: integer;

    fNodeText: string;

    fID: integer;

    fData: string;

    fSaver: TAdoQuery;

    fChanged: Boolean;        

    fSaveImmediate: boolean;

    fIsNew: Boolean;

    fImageIndex: integer;

    procedure SetData(const Value: string);

    procedure SetNodeText(const Value: string);

    procedure SetParentID(const Value: integer);

    procedure SetStatus(const Value: byte);

    procedure SetImageIndex(const Value: integer);

  protected

    procedure Changed; dynamic;

  public

    constructor Create(aSaver: TAdoQuery; AId, AParentID: integer; AStatus: byte);

    constructor LoadFromDataset(aSaver: TAdoQuery);

    procedure BeginUpdate;

    procedure EndUpdate;

    procedure Delete;

    procedure Save;

  published

    property ID: integer read fID write fID;

    property ParentID: integer read fParentID write SetParentID;

    property ImageIndex: integer read fImageIndex write SetImageIndex;

    property Status: byte read FStatus write SetStatus;

    property Data: string read fData write SetData;

    property NodeText: string read fNodeText write SetNodeText;

  end;
 

{ TItem }
 

procedure TItem.BeginUpdate;

begin

  fSaveImmediate := false;                 

end;

(*---------------------------------------------------*)

procedure TItem.Changed;

begin

  fChanged := True;

  if fSaveImmediate then Save;

end;

(*---------------------------------------------------*)

constructor TItem.Create(aSaver: TAdoQuery; AId, AParentID: integer;

  AStatus: byte);

begin

  inherited Create;

  fChanged := False;

  fSaveImmediate := True;

  fIsNew := True;

  fSaver := aSaver;

  fID := AID;

  fParentID := AParentID;

  fStatus := AStatus;

  fNodeText := '';

  fData := '';

end;

(*---------------------------------------------------*)

procedure TItem.Delete;

begin

//

end;

(*---------------------------------------------------*)

procedure TItem.EndUpdate;

begin

  fSaveImmediate := True;

  if fChanged then Save;

end;

(*---------------------------------------------------*)

constructor TItem.LoadFromDataset(aSaver: TAdoQuery);

begin

  Create(aSaver, 0, 0, 0);

  if not aSaver.IsEmpty then

  begin

    fId := aSaver.FieldByName('ID').AsInteger;

    fParentID := aSaver.FieldByName('PARENT').AsInteger;

    fStatus := aSaver.FieldByName('STATUS').AsInteger;

    fNodeText := aSaver.FieldByName('NAME').AsString;

    if aSaver.FindField('DATA') <> nil then

      fData := aSaver.FieldByName('DATA').AsString;

    fImageIndex := aSaver.FieldByName('IMAGE_INDEX').AsInteger;

    fIsNew := False;

  end;

end;

(*---------------------------------------------------*)

procedure TItem.Save;

begin

  if fIsNew then

    fSaver.SQL.Text :=

      'insert into tree (parent, name, status, image_index, data) values (:v1, :v2, :v3, :v4, :v5)'

  else

    fSaver.SQL.Text :=

      'update tree set parent = :v1, name = :v2, status = :v3, image_index = :v4, data = :v5 where id = :v6';

  fSaver.Parameters.ParamByName('v1').Value := fparentID;

  fSaver.Parameters.ParamByName('v2').Value := fNodeText;

  fSaver.Parameters.ParamByName('v3').Value := fStatus;

  fSaver.Parameters.ParamByName('v4').Value := fImageIndex;

  fSaver.Parameters.ParamByName('v5').Value := fData;

  if not fIsNew then

    fSaver.Parameters.ParamByName('v6').Value := fId;

  fSaver.ExecSQL;

  if fIsNew then

  begin

    fSaver.SQL.Text :=

      'SELECT id from tree order by id desc';

    fSaver.Open;

    fId := fSaver.FieldByName('ID').asInteger;

    fSaver.Close;

    fIsNew := False;

  end;

  fChanged := False;

end;

(*---------------------------------------------------*)

procedure TItem.SetData(const Value: string);

begin

  if fData <> Value then

  begin

    fData := Value;

    Changed;

  end;

end;

(*---------------------------------------------------*)

procedure TItem.SetImageIndex(const Value: integer);

begin

  if fImageIndex <> Value then

  begin

    fImageIndex := Value;

    Changed;

  end;

end;

(*---------------------------------------------------*)

procedure TItem.SetNodeText(const Value: string);

begin

  if fNodeText <> Value then

  begin

    fNodeText := Value;

    Changed;

  end;

end;

(*---------------------------------------------------*)

procedure TItem.SetParentID(const Value: integer);

begin

  if fParentId <> Value then

  begin

    fParentID := Value;

    Changed;

  end;

end;

(*---------------------------------------------------*)

procedure TItem.SetStatus(const Value: byte);

begin

  if fStatus <> Value then

  begin

    FStatus := Value;

    Changed;

  end;

end;

(*---------------------------------------------------*)

procedure TForm1.AddItem(aText: string; aIndex: Integer; aParent: TTreeNode);

var n: TTreeNode;

  data: TItem;

  parentId: integer;

begin

  parentId := 0;

  if (aParent <> nil) and (TItem(aParent.Data) <> nil) then

    parentId := TItem(aParent.Data).ID;

  data := TItem.Create(AdoQuery1, -1, parentId, 0);

  data.NodeText := aText;

  data.ImageIndex := aIndex;

  n := TTreeNode.Create(TreeView1.Items);

  n.Text := data.NodeText;

  n.ImageIndex := data.ImageIndex;

  n.SelectedIndex := data.ImageIndex;

  TreeView1.Items.AddNode(n, aParent, aText, data, naAddChild);

end;

(*---------------------------------------------------*)

procedure TForm1.Button1Click(Sender: TObject);

begin

  loadTree(treeview1);

end;

(*---------------------------------------------------*)

procedure TForm1.Button2Click(Sender: TObject);

begin

  savetree(treeview1);

end;

procedure TForm1.Button3Click(Sender: TObject);

var

   node : TTreeNode;

   mess, str : string;

   key_stat : integer;

begin

    Node := Treeview1.Selected;

    if Assigned(Node) then

       begin

       str := Node.Text;

       mess := 'Are you sure that you want to delete the';

       Case Node.Level of

         0 : mess := mess + ' folder : ' +#13+#13 + str + '   ???' +#13+

                    'All folders, subfolders, items and subitems' +#13+ 'will be permanently deleted !!' +#13;

         1 : mess := mess + ' item : ' +#13+#13 + str + '   ???' + #13;

       end;

       with Application do

         begin

         NormalizeTopMosts;

         key_stat := MessageBox(pchar(mess), '         Confirmation', MB_YESNO);

         RestoreTopMosts;

       end;

       if key_stat = 7 then  Exit;         // 6 - YES ; 7 - N0

       TreeView1.Items.Delete(Treeview1.Selected);

       end

    else ShowMessage('Select a folder in the treeview first.');

end;

(*---------------------------------------------------*)

procedure TForm1.FileBtnClick(Sender: TObject);

var aText: string;

begin

  if (TreeView1.Selected <> nil) and (TreeView1.Selected.ImageIndex = 15) then

  begin

     if InputQuery('File', 'Enter a file name', aText) then

      AddItem(aText, 17, TreeView1.Selected);

  end else

    ShowMessage('Select a folder in the treeview first.');

end;

(*---------------------------------------------------*)

function TForm1.findNode(t: TTreeView; id: integer): TTreeNode;

var i:integer;

begin

  i:=0;

  while (i<t.items.count) and (TItem(t.items[i].data).ID<>id) do

    inc(i);

  if i<t.items.count then result:=t.items[i]

                     else result:=nil;

end;

(*---------------------------------------------------*)

procedure TForm1.FolderBtnClick(Sender: TObject);

var aText: string;

  aParent: TTreeNode;

begin

  aParent := nil;

  if TreeView1.Selected <> nil then

  begin

    if TreeView1.Selected.ImageIndex = 15 then

      aParent := TreeView1.Selected

    else

    begin

      ShowMessage('Select a folder first');

      Exit;

    end;

  end;

  if InputQuery('Folder', 'Enter a folder name', aText) then

    AddItem(aText, 15, aParent);

end;

(*---------------------------------------------------*)

procedure TForm1.FormCreate(Sender: TObject);

var

  conn_str:string;

begin

  conn_str:='provider=Microsoft.Jet.OLEDB.4.0;Persist Security Info=False;Data Source=';

  conn_str:=conn_str+IncludeTrailingPathDelimiter(ExtractFilePath(Application.Exename));

  conn_str:=conn_str+'test.pkd;';

  ADOConnection1.Connected:=False;

  ADOConnection1.ConnectionString:=conn_str;

  ADOConnection1.Connected:=True;

  ADOConnection1.Open;

end;

(*---------------------------------------------------*)

procedure TForm1.loadtree(t: TTreeView);

var

  p, n: TTreeNode;

  data: TItem;

begin

  t.Items.Clear;

  ADOQuery1.SQL.Text := 'select * from tree order by parent asc';

  ADoQuery1.Open;

  while not ADoQuery1.Eof do

  begin

    data := TItem.LoadFromDataset(AdoQuery1);

    p := FindNode(t, data.ParentID);

    n := t.items.AddChildObject(p, data.NodeText, data);

    n.ImageIndex := data.ImageIndex;

    n.SelectedIndex := data.ImageIndex;

    AdoQuery1.Next;

  end;

  AdoQuery1.Close;

end;

(*---------------------------------------------------*)

procedure TForm1.saveNode(n: TTreeNode);

var i, aParent: integer;

  item: TItem;

begin

  item := TItem(n.Data);

  if item <> nil then

  begin

    item.BeginUpdate;

    try

      Item.NodeText := n.Text;

      aParent := 0;

      if (n.Parent <> nil) and (TItem(n.Parent.Data) <> nil) then

        aParent := TItem(n.Parent.Data).ID;

      Item.ParentID := aParent;

      Item.ImageIndex := n.ImageIndex;

    finally

      Item.EndUpdate;

    end;

  end;

  for i := 0 to n.Count-1 do SaveNode(n.Item[i]);

end;

(*---------------------------------------------------*)

procedure TForm1.savetree(t: ttreeview);

var n: TTreeNode;

begin

  n := t.items.getFirstNode;

  while n <> nil do

  begin

    SaveNode(n);

    n := n.getNextSibling;

  end;

end;

(*---------------------------------------------------*)

procedure TForm1.TreeView1Change(Sender: TObject; Node: TTreeNode);

begin

  RichEdit1.Text := '';

  if (Node <> nil) and (Node.ImageIndex = 15) then

    RichEdit1.Text := TItem(Node.Data).Data;

end;

(*---------------------------------------------------*)

procedure TForm1.RichEdit1KeyUp(Sender: TObject; var Key: Word;

  Shift: TShiftState);

  var n: TTreeNode;

begin

        n := TreeView1.Selected;

        if (n <> nil) and (n.ImageIndex = 15) then

        begin

        TItem(n.Data).fSaveImmediate := False;

         TItem(N.Data).Data := RichEdit1.Text;

         end;

end;

(*---------------------------------------------------*)

end.

Open in new window

0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Delphi OLE Error 8 95
URL for downloading Google Chrome for Win XP 2 125
Convert GUI app into console app for Win32 Env 5 81
How to renew a Delphi rad-studio licence? 5 49
The uses clause is one of those things that just tends to grow and grow. Most of the time this is in the main form, as it's from this form that all others are called. If you have a big application (including many forms), the uses clause in the in…
In my programming career I have only very rarely run into situations where operator overloading would be of any use in my work.  Normally those situations involved math with either overly large numbers (hundreds of thousands of digits or accuracy re…
This Micro Tutorial demonstrates using Microsoft Excel pivot tables, how to reverse engineer competitors' marketing strategies through backlinks.
Sending a Secure fax is easy with eFax Corporate (http://www.enterprise.efax.com). First, just open a new email message. In the To field, type your recipient's fax number @efaxsend.com. You can even send a secure international fax — just include t…

867 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

20 Experts available now in Live!

Get 1:1 Help Now