CODEWITHSUNDEEP
delphidelphi-xe2
Sharpie
Sharpie

Reputation: 383

Cannot assign to a read only property

I have a form which has a TDBLookupComboBox on it.

The TDBLookupComboBox is displaying a list of records from within a database table.

At the point of the forms OnShow event I would like the TDBLookupComboBox to already display one of the strings in the list.

I have done this so far...

procedure TfrmMain.FormShow(Sender: TObject);
begin
  dblucbox.Text := Username;
end

Username is a string for one of the records already in the list.

At the point of compiling, I get an error saying

Cannot assign to a read only property

I'm a bit stuck with this so any help would be appreciated.

Upvotes: 1

Views: 2189

Answers (2)

David Schwartz
David Schwartz

Reputation: 1838

You're going about this backwards. To be more precise, the DBLookupCombo is reflecting the state of the database table. So you want to be manipulating the table, not the combobox.

In other words, the OnShow event needs to open the table that's the object of the DBLookupCombo (if it's not already open) and then position the current record to be the one you want displayed as the default.

Upvotes: 2

RRUZ
RRUZ

Reputation: 136391

Don't try to modify the Text property, instead if you want set the TDbLookUpComboBox in a particular item you must use the the KeyValue property which will try to locate the record in the underlying TDataSet.

So you if you have Key Value of the user you can use something like this 

 dblucbox.KeyValue := UserId;

Otherwise you can use the Locate method of the underlying TDataSet, to find the match and the LookUp control will be refreshed automatically

Upvotes: 3

Related Questions