[SOLVED] Multi Delete from a TRxDBGrid
lazarus / 16-Databases

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donnie · 2016-03-22 09:47

Hi there,
I've got a TRxDBGrid(almost the same with DBGrid just has much more
functions) connected to a datasource (which is connected to a
tzquery.dataset). The TRxDBGrid Options allow me to have multi
selection to rows(Options->dgMultiselect ->True). Can I have multi
delete from this TRxDBGrid ? I have connected this TRxDBGrid  with a
TDBnavigator and when I select more than one row and press the delete
button(-) from navigator no multi delete happens.  It just deletes the
first selected row. I don't want to use TDBnavigator  if possible. in
order to delete only one row I use the following code:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  index :=
FindColumnIndex(TRxDBGrid1  , 'NUM');//FindColumnIndex finds the index
of the column NUM from the  TRxDBGrid1    TRxDBGrid1.SelectedIndex :=
index;  deletednum:= TRxDBGrid1.Columns.Items[index].Field.Value;  if
MessageDlg('Delete Number', 'Do you wish to Delete this NUM ?',
mtConfirmation, [mbYes, mbNo], 0) = mrYes then  begin     
DbModule.GeneralQuery.Close;      DbModule.GeneralQuery.Connection :=
DbModule.ZConnection1;      DbModule.GeneralQuery.SQL.Clear;     
DbModule.GeneralQuery.SQL.Text := 'DELETE FROM TABLE WHERE NUM= ' +
InttoStr(deletednum);      DbModule.GeneralQuery.ExecSQL;     
TRxDBGrid1.DataSource.DataSet.Refresh; (I have posted the same topic
at the category databases but I believe this is the right path
Programming»Databases)
Any help if possible .
Thank you.

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mangakissa · 2016-03-22 12:27

Normally only the selected record will be deleted. the deletebutton on
your navigator doesn't know the multiple records are selected. You
have to override de navigator post button with a procedure that tells
if your records are selected or not.
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.DBNavigator1Click(Sender: TObject; Button:
TDBNavButtonType);begin  if Button = nbPost then  begin    if
DBGrid1.SelectedRows.Count > 0 then    begin      with
DBGrid1.DataSource.DataSet do      begin        for i := 0 to
DBGrid1.SelectedRows.Count-1 do        begin         
GotoBookmark(Pointer(DBGrid1.SelectedRows.Items[i]));         
Deleterecordprocedure        end;      end;    end else     
DBGrid1.DataSource.DataSet.post;  end;end; The only thing I'm not sure
if other navigator buttons are working if you overide the onclick
procedure. In that case you have to program each button.

You also can use this procedure without TNavigator.

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rvk · 2016-03-22 12:33

Quote from: nek on March 22, 2016, 10:47:37 amI don't want to use
TDBnavigator  if possible.
mangakissa beat me to it... you do indeed need to use SelectedRows
(TBookmarks for the TDataset) to delete all records.

But because you said you wanted to avoid the TDBNavigator here is a
method of using the Ctrl+Delete in the DBGrid. You can use this for
rxDBGrid too. Just add this in the OnKeyDown event:

It works for single and multiple selected records. It "overrides" the
normal Ctrl+Delete and in case multiple records are selected, it loops
through all of them and deletes them. In case 1 record is selected the
it passes through and the normal Ctrl+Delete is executed.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i uses
LCLType, LCLStrConsts; procedure TForm1.DBGrid1KeyDown(Sender:
TObject; var Key: word; Shift: TShiftState);var  idx: integer; 
myGrid: TDBGrid;  myDataset: TDataset;begin  if (Key = VK_DELETE) and
(ssCtrl in Shift) then  begin    if Sender.InheritsFrom(TDBGrid) then 
  begin      myGrid := TDBGrid(Sender);      myDataset :=
myGrid.DataSource.DataSet;      if (myGrid.SelectedRows.Count > 1)
then      begin        Key := 0; // ONLY in case of > 1, otherwise do
the default Ctrl+Delete        if MessageDlg(format('Delete %d
records?', [myGrid.SelectedRows.Count]),          mtConfirmation,
mbOKCancel, 0) <> mrCancel then        begin          for idx := 0 to
myGrid.SelectedRows.Count - 1 do            if
myDataset.BookmarkValid(TBookmark(myGrid.SelectedRows.Items[idx]))
then            begin             
myDataset.GotoBookMark(Pointer(myGrid.SelectedRows.Items[idx]));     
       myDataset.Delete;            end;        end;      end;   
end;  end;end;

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marcov · 2016-03-22 16:37

Bookmark handling varies wildly with Delphi version too. D2006, D2007
and D2009+ are all different.

Still afaik FPC 3.0 should be ok, since it is a TBytes. It might go
wrong already at the point where items[] is filled. Or maybe if you
change the gotobookmark cast to TBookmark()

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rvk · 2016-03-22 16:43

Argh... I can't reproduce it anymore. It was with Laz1.7/FPC 3.1.1
(trunk) and I kept having memory-leaks multiple times 75 bytes. But I
just tested it again and now it works fine.

(Either way... FreeBookmark did nothing because the define
noautomatedbookmark was on)

(I removed the FreeBookmark from my snippet)

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donnie · 2016-03-23 09:18

Excellent!!!
You've been more than helpful.
I used rvk's solution as it helped me a lot.
Both solutions mangakissa and rvk will help me in other commands that
I want to execute in multi selected rows, not only the delete
procedure.
Thank you, once again.