我的DBTreeView--TreeView直接连接数据表

认真研究如下代码：DBTreeView--TreeView直接连接数据表

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, DB, DBTables, ComCtrls, Grids, DBGrids, ExtCtrls,
  DBCtrls, Mask, ImgList;

type
  TForm1 = class(TForm)
    TreeView1: TTreeView;
    ImageList1: TImageList;
    DataSource1: TDataSource;
    DBEdit1: TDBEdit;
    Label1: TLabel;
    Label2: TLabel;
    DBEdit2: TDBEdit;
    Table1: TTable;
    Label3: TLabel;
    DBNavigator1: TDBNavigator;
    Label4: TLabel;
    DBEdit3: TDBEdit;
    DBEdit4: TDBEdit;

    procedure FormCreate(Sender: TObject);
    procedure TreeView1Change(Sender: TObject; Node: TTreeNode);
    procedure DataSource1StateChange(Sender: TObject);
    procedure Table1AfterInsert(DataSet: TDataSet);
    procedure Table1BeforeDelete(DataSet: TDataSet);
    procedure Table1BeforeEdit(DataSet: TDataSet);
    procedure Table1AfterDelete(DataSet: TDataSet);
    procedure Table1AfterPost(DataSet: TDataSet);
  private
    function  GetFieldList: TStringList;
    { Private-Declarationen }
  public
    { Public-Declarationen }
  end;

var
  Form1: TForm1;
  FieldList: TStringList;

implementation
uses TreeFunc;

{$R *.DFM}

function TForm1.GetFieldList: TStringList;
begin
     FieldList.clear;
     FieldList.add(Table1.fieldbyname('Country').asstring);
     FieldList.add(Table1.fieldbyname('city').asstring);
     FieldList.add(Table1.fieldbyname('Company').asstring);
     Result := FieldList;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
     FieldList := TStringList.create;
     TreeView1.items.BeginUpdate;//forbid treeview update
     Table1.first;
     while not Table1.eof do
       begin
          TreeAddItem(TreeView1, GetFieldList, Table1.getBookmark, false);//生成结点
          Table1.next;
       end;
     FieldList.clear;
     TreeView1.Alphasort;
     TreeView1.items.Endupdate;

//make first record selected:
     TreeView1.items[2].selected := true;
end;

procedure TForm1.TreeView1Change(Sender: TObject; Node: TTreeNode);
begin
     Datasource1.enabled := Node.data <> nil;
     if DataSource1.enabled then Table1.Gotobookmark(node.data);
end;

procedure TForm1.DataSource1StateChange(Sender: TObject);
var
   ItemList: TStringList;
   Node: TTreeNode;
begin
end;

procedure TForm1.Table1AfterInsert(DataSet: TDataSet);
begin
     FieldList.clear;
end;

procedure TForm1.Table1BeforeDelete(DataSet: TDataSet);
begin
     GetFieldList;
end;

procedure TForm1.Table1BeforeEdit(DataSet: TDataSet);
begin
     GetFieldList;
end;

procedure TForm1.Table1AfterDelete(DataSet: TDataSet);
var
   CascadeDeleteLevel: Integer;
begin
     CascadeDeleteLevel := 0;
     TreeDeleteItem(TreeView1, FieldList, CascadeDeleteLevel);
end;

procedure TForm1.Table1AfterPost(DataSet: TDataSet);
begin
     TreeView1.items.beginUpdate;

     if FieldList.count > 0 then TreeDeleteItem(TreeView1, Fieldlist, 0);
     TreeView1.selected := TreeAddItem(TreeView1, GetFieldlist, Table1.getbookmark, True);

     TreeView1.items.endUpdate;
end;

end.
///------------------------
unit TreeFunc;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, ComCtrls, DB, Forms, Dialogs;

function  TreeFindItem(Sender: TTreeView; NodeItem: TTreeNode; Name: String): TTreeNode;
function  TreeAddItem(Sender: TTreeView; ItemList: TStrings; Bookmark: TBookmark; Resort: Boolean): TTreeNode;
function  TreeGetItem(Sender: TTreeView; ItemList: TStrings): TTreeNode;
procedure TreeDeleteItem(Sender: TTreeView; ItemList: TStrings; Level: Integer);

implementation

function TreeAddItem(Sender: TTreeView; ItemList: TStrings; Bookmark: TBookmark; Resort: Boolean): TTreeNode;
var
   ThisNode, Node: TTreeNode;
   I: Integer;
begin
     Node := nil;   //nil = level 0 has no parent node
                    //this is checked by TreeFindItem
     for I := 0 to Itemlist.count -1 do
        begin //for
          ThisNode := TreeFindItem(Sender, node, Itemlist[i]);
          if ThisNode <> nil then
            Node := ThisNode
          else
            begin
               if I < Itemlist.count -1 then
                 begin
                    if I = 0 then
                      Node := Sender.items.Add(Node, Itemlist[i])
                    else
                      Node := Sender.items.AddChild(Node, Itemlist[i]);
                 end
               else
                 begin
                    if I = 0 then
                      Node := Sender.items.AddObject(Node, Itemlist[i], Bookmark)
                    else
                      Node := Sender.items.AddChildObject(Node, Itemlist[i], Bookmark);
                 end;
               Node.stateIndex := Node.level + 1;
               if Resort and (Node.parent <> nil) then Node.parent.alphasort;
            end;
        end; //for
     Result := Node;
end;

function TreeFindItem(Sender: TTreeView; NodeItem: TTreeNode; Name: String): TTreeNode;
begin
     if NodeItem = nil then NodeItem := Sender.items.getfirstnode
     else NodeItem := NodeItem.getfirstchild;
//NodeItem is now the first item of the desired level
//if this level has no items, NodeItem is nil

     if (NodeItem <> nil) and (NodeItem.text <> Name) then
     repeat
           NodeItem := NodeItem.getnextsibling;
     until (NodeItem = nil) or (NodeItem.text = Name);
     Result := NodeItem;
end;

function TreeGetItem(Sender: TTreeView; ItemList: TStrings): TTreeNode;
begin
     Result := TreeAddItem(Sender, Itemlist, nil, false);
end;

procedure TreeDeleteItem(Sender: TTreeView; ItemList: TStrings; Level: Integer);
var
   Node, Parent: TTreeNode;
begin
     Node := TreeGetItem(Sender, ItemList);
     while Node.level >= Level do
     begin
          Parent := Node.parent;
          Node.delete;
          if (Parent = nil) or (Parent.hasChildren) then break;
          Node := Parent;
     end;
end;

end.

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