How to get the value that caused the TDBGridInplaceEdit error?

Question

I'm trying to write an exception handler that displays user friendly messages. I don't know how to get the "Newly Entered" data value that caused the TDBGridInplaceEdit error.

For example:
I have a DBGrid loaded with data. When I intentionally change the PartNo field of row #1 to a non numeric value to cause a TDBGridInplaceEdit error... (From: 1313.3 To: 1313..3) ... I trap the error and display a message but I can't figure out how to get the bad '1313..3' value.

Original PartNo: 1313.3


Changed PartNo: 1313..3 (two decimal points)


Displayed Error Message from the Application onException

procedure TMain.ApplicationEvents1Exception(Sender: TObject; E: Exception);
var
  str : string;
begin
  str := sender.ToString;
  str := str + #10;
  str := str + RzDBGrid2.SelectedField.FieldName;
  str := str + #10;
  str := str + VarToStr(RzDBGrid2.SelectedField.Value);
  str := str + #10;
  str := str + e.Message;
  showmessage(str);
  //Application.ShowException(E);
end;

I'd like to format my own message using the bad '1313..3' value that was entered. How do you get this value?

Answer 1

If you are persisting the fields of your dataset, you can define an OnSetText Method on your fields.(Doubleclick on the dataset and choose add fields).

The Method could look like this:

procedure TForm1.ADataSetAFloatFieldSetText(Sender: TField; const Text: string);
var
 f:Double;
begin
  if not TryStrToFloat(Text,f) then
      begin
       raise Exception.Create(
                              'Error on: '
                              + #13#10'Dataset: '   + Sender.DataSet.Name 
                              + #13#10'Field: '     + Sender.FieldName 
                              + #13#10'Old Value: ' + Sender.AsString 
                              + #13#10'New Value: ' + Text
                             );
      end;
end;

If you want to avoid persisting your fields you can dynamically assign the Method to the field, e.g. after opening the Dataset.

procedure TForm1.ADataSetAfterOpen(DataSet: TDataSet);
Var
 i:Integer;
begin
  for I := 0 to Dataset.FieldCount - 1 do
      begin
        if Dataset.Fields[i].DataType in [ftFloat, ftCurrency, ftBCD] then
           Dataset.Fields[i].OnSetText := ADataSetAFloatFieldSetText;            
      end;
end;