cxGrid - Footer summary of checked records

Question

In cxGrid,I have a column that is boolean (properties : checkbox). How can I do a footer summary (SUM) of such a column i.e to sum how many records are checked.

Right now, if I set it to SUM, my footer summary displays negative numbers for the items checked.How can I avoid these negative numbers?

edit : I have found a would be solution on their site with :

procedure TForm1.cxGrid1DBTableView1DataControllerSummaryFooterSummaryItemsSummary(
  ASender: TcxDataSummaryItems; Arguments: TcxSummaryEventArguments;
  var OutArguments: TcxSummaryEventOutArguments);
var
  si: TcxGridDBTableSummaryItem;
begin
  si := Arguments.SummaryItem as TcxGridDBTableSummaryItem;
  if si.Column = cxGrid1DBTableView1Sonda then
    OutArguments.Done := not OutArguments.Value;
end;

However I am getting the error : Could not convert variant of type (Null) into type (Boolean).

Dont understand this. Field is boolean type (bit).

edit2:

The problem is that sql server by default sets boolean type to NULL. That is why the conversion error.

I'd ask [here](https://www.devexpress.com/Support/Center/Question/List/1). — Uli Gerhardt, May 16 '17 at 07:08
Unfortunately there is no answer : https://www.devexpress.com/Support/Center/Question/Details/S136683 — user763539, May 16 '17 at 07:12
DevExpress always extensively updates their products and their support has greatly improved. That question you linked is 7 years old and migrated from their old support system. You should just ask it yourself again. — R-D, May 16 '17 at 07:33
Regarding your edit: I guess you have to decide if you want `Null`s counted as checked or not and work with `VarIsNull` accordingly. — Uli Gerhardt, May 16 '17 at 08:47
OK, then I'd try handling it that way - probably using `VarIsNull`, as written above. :-) — Uli Gerhardt, May 16 '17 at 09:00
What database do you use? what is type of that column in database? — mikia, May 16 '17 at 10:06

Marc Guillot · Answer 1 · 2017-05-17T06:55:29.620

You can also just set your grid to calculate that summary using a different field , for example a calculated field where you assign the exact value you want to add each time.

Add a calculated field to your dataset, with the desired value. MyHiddenField.Value := -1 * YourCheckingField.AsInteger;
Go to the Summaries Tab on the CxGrid dialog, and add a new Summary:
1. Set the Column property to the Grid Column where you want it to appear
2. Set the FieldName to your calculated field
3. And finally set Kind to skSum

score 1 · Answer 2 · answered May 16 '17 at 10:22

It is better to send such questions to DevExpress support team. You can customize footer:

assign Kind=skNone to footer summary item
use OnGetText event to show what you want

Quick example (shows number of chars in all records as footer value):

procedure TForm54.cxGrid1DBTableView1TcxGridDBDataControllerTcxDataSummaryFooterSummaryItems0GetText(
  Sender: TcxDataSummaryItem; const AValue: Variant; AIsFooter: Boolean;
  var AText: string);
var i,j: integer;
begin
  j := 0;
  for i := 0 to cxGrid1DBTableView1.DataController.RecordCount-1 do
    j := j + Length(String(cxGrid1DBTableView1.DataController.Values[i, cxGrid1DBTableView1c.Index]));
  AText := IntToStr(j);
end;

score 0 · Answer 3 · answered May 16 '17 at 11:29

0

I think that you can resolve that problem in SQL component. Use typecasting and your cxGrid will work with Integer values.

SELECT CAS(Bit_Column AS int) AS Int_Column
FROM YourTable

answered May 16 '17 at 11:29

mikia

454
1
4
14

score 0 · Answer 4 · answered May 16 '17 at 15:31

You can try this :

procedure TForm1.cxGrid1DBTableView1DataControllerSummaryAfterSummary(
  ASender: TcxDataSummary);
var i, j, Imp:integer;
    Item: TcxGridDBTableSummaryItem;
begin
  DBTableView1.DataController.BeginLocate;
  for j:=0 to ASender.FooterSummaryItems.Count-1 do ASender.FooterSummaryValues[j]:=0;
  try
    for i:=0 to DBTableView1.DataController.RowCount-1 do
    begin
      if (DBTableView1.DataController.Values[i,cxGrid1DBTableView1Sonda.Index]<>null) then
        for j:=0 to ASender.FooterSummaryItems.Count-1 do
        begin
          Item:=TcxGridDBTableSummaryItem(ASender.FooterSummaryItems[j]);
          Imp:= DBTableView1.DataController.Values[i, cxGrid1DBTableView1Sonda.Index];
          if (Imp= 1) or ((Imp= 2) 
          then ASender.FooterSummaryValues[j]:= ASender.FooterSummaryValues[j]+1;
        end;
    end;
  finally
    DBTableView1.DataController.EndLocate;
  end;
end;

score 0 · Answer 5 · answered May 17 '17 at 01:05

procedure cxGrid1DBTableView1DataControllerSummaryFooterSummaryItemsSummary(
  ASender: TcxDataSummaryItems; Arguments: TcxSummaryEventArguments;
  var OutArguments: TcxSummaryEventOutArguments);

    var
      AValue: Variant;
      AItem: TcxGridTableSummaryItem;
    begin
      AItem := TcxGridTableSummaryItem(Arguments.SummaryItem);

      // считаем проверенные
      if (AItem.Column = tvCompareisCorrect) and (AItem.Kind = skCount) and (AItem.Position = spFooter) then begin
        AValue := tvCompare.DataController.Values[ Arguments.RecordIndex, tvCompareisCorrect.Index];
        if not VarIsNull(AValue) then
          if not VarAsType(AValue, varBoolean) then Dec(OutArguments.CountValue);
      end;

This answer needs some explanation as to what you have changed and how this fixes the problem — Jayden Meyer, May 17 '17 at 02:27

cxGrid - Footer summary of checked records

5 Answers5