求助!! treeview

[CNNO01]

我现在要从数据库中生成树,部分代码如下
type
PTreeNodePnt = ^TTreeNodePnt;
TTreeNodePnt = record
T_Id: string;
T_Value: string;
end;

procedure TMainForm.FormCreate(Sender: TObject);
var
PTree: PTreeNodePnt;
TemQ: TADOQuery;
TempNode:　TreeNode;
begin
with TreeQ do
begin
Close;
SQL.Clear;
SQL.Add('select * from T_SYS_PARAMETER');
Open;
while not eof do
begin
New(PTree);
PTree^.T_Id := FieldByName('CONTENT_ID').asstring;
PTree^.T_Value := FieldByName('CONTENT').AsString;
if TreeQ.FieldByName('ROOT_ID').AsInteger = id1 then
begin
TempNode:= TreeView1.Items.AddChildObject(Treeview1.Items[0],Ptree^.T_Value,PTree);
GetNxtNode(FieldByName('CONTENT_ID').AsInteger,TempNode);
end;
Next;
end;
end;

procedure TMainForm.TreeView1Change(Sender: TObject; Node: TTreeNode);
var
id: string;
begin
if Treeview1.Selected.Level = 1 then
id := TTreeNodePnt(Treeview1.selected.data^).T_id; //正确;
if Treeview1.Selected.Level = 2 then
id := TTreeNodePnt(Treeview1.selected.data^).T_id; // 在这里就出错了,这是最后一个节点
......
end;

初学D不久,请问为什么在这里会出错, access iolation at address 004c07a6
in module 'project1.exe'

[risman]

关注一下

[CNNO01]

顶一下

[zuoansuifeng]

你调试进去的时候有没有查它结点的id值啊~` 而且Treeview1.Selected.Level 选择哪个结点之前要判断结点是否为空~~~

[CNNO01]

应该不会为空,我这个事件是在 treeview 的onchang事件中的啊

[CNNO01]

帮帮忙啊 !

[CNNO01]

ding

[王集鹄]

//move TreeView1Changing->TreeView1Change

procedure TForm1.TreeView1Change(Sender: TObject; Node: TTreeNode);
var
id: string;
begin
if not Assigned(TreeView1.Selected) then Exit; // insert

if TreeView1.Selected.Level = 1 then
id := TTreeNodePnt(TreeView1.Selected.Data^).T_id; //正确;
if TreeView1.Selected.Level = 2 then
id := TTreeNodePnt(TreeView1.Selected.Data^).T_id; // 在这里就出错了,这是最后一个节点
Caption := id;
end;