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add data to Tstrings

 
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Nathan
Guest
PostPosted: Mon Nov 24, 2003 11:31 pm    Post subject: add data to Tstrings Reply with quote


Hi everybody

I create a TComboBox with some data in the items when I add it to form I
got a ErrMsg "Control has no parent window" I debug it I see it stop when
it add the data to the items property

Here is the my code



TdsDateComboBox = class(TCustomComboBox);

....



constructor TdsDateComboBox.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
Style:= csDropDownList;
Items.Add('All');
Items.Add('Today');
Items.Add('This Week');
Items.Add('This Week-to-date');



Please reply thanks

Nathan


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Yorai Aminov (TeamB)
Guest
PostPosted: Tue Nov 25, 2003 12:22 am    Post subject: Re: add data to Tstrings Reply with quote


On Mon, 24 Nov 2003 18:31:45 -0500, "Nathan" <nerenthal (AT) hotmail (DOT) com>
wrote:

Quote:
I create a TComboBox with some data in the items when I add it to form I
got a ErrMsg "Control has no parent window"

You're trying to access the combo box items in the constructor.
Unfortunately, the items list is implemented as a wrapper around the
standard combo box messages. This means they are only accessible once
a window handle is created.

You can override the CreateWnd method and add your items then. Note
that the method is called whenever the window is recreated, so you'll
probably want to set a flag somewhere to avoid inserting the items
more than once.

---
Yorai Aminov (TeamB)
http://develop.shorterpath.com/yorai
(TeamB cannot answer questions received via email.)

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JED
Guest
PostPosted: Tue Nov 25, 2003 12:29 am    Post subject: Re: add data to Tstrings Reply with quote


Nathan wrote:

Quote:
Hi everybody

I create a TComboBox with some data in the items when I add it to
form I got a ErrMsg "Control has no parent window" I debug it I see
it stop when it add the data to the items property


You could override the Loaded method and add the items there.

HTH,

jed


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Peter Below (TeamB)
Guest
PostPosted: Tue Nov 25, 2003 6:46 pm    Post subject: Re: add data to Tstrings Reply with quote
In article <3fc294ba$1 (AT) newsgroups (DOT) borland.com>, Nathan wrote:
Quote:
I create a TComboBox with some data in the items when I add it to form I
got a ErrMsg "Control has no parent window" I debug it I see it stop when
it add the data to the items property

Here is the my code

TdsDateComboBox = class(TCustomComboBox);

constructor TdsDateComboBox.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
Style:= csDropDownList;
Items.Add('All');
Items.Add('Today');
Items.Add('This Week');
Items.Add('This Week-to-date');

As indicated by the other replies you cannot do things in the constructor
that require the controls window handle to exist. But using Items.Add should
work without the handle, the control will buffer the data into a temp
TStringlist instance. What does require the window handle, however, is an
attempt to set the ItemIndex. You should move that to an overriden CreateWnd
or SetParent method.

--
Peter Below (TeamB)
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