Delphi Using Locate function in data source in memory table

I need to check given value is already exists in the memory table, so i have tried following method.

function TForm4.findValueExists(id: Integer): Boolean; var state: Boolean; begin state := DBGrid1.DataSource.DataSet.Locate('code', id, []); end; 

here is the Search button procedure

procedure TForm4.butSearchClick(Sender: TObject); var id: Integer; Name: String; Sell: Double; Qty: Integer; Amount: Double; OldQty: Integer; RecordExist: Boolean; begin if txtprocode.Text <> '' then begin FDQuery1.Params.ParamByName('ID').Value := txtprocode.Text; if FDQuery1.Active then FDQuery1.Close; FDQuery1.Open(); try FDQuery1.First; if not FDQuery1.Eof then begin id := FDQuery1.FieldByName('Id').AsInteger; Name := FDQuery1.FieldByName('name').AsString; Sell := FDQuery1.FieldByName('selling').AsFloat; Qty := 1; Amount := Sell * Qty; if Form4.findValueExists(id) then begin FDMemTable1.Edit; OldQty := DBGrid1.Fields[3].Value; FDMemTable1.FieldByName('Qty').AsInteger := (OldQty + 1); FDMemTable1.FieldByName('amount').AsFloat := (Sell * (OldQty + 1)); FDMemTable1.Post; end else begin FDMemTable1.InsertRecord([id, Name, Sell, Qty, Amount]); end; end; finally end; end; end; 

unfortunately this method always gives me result as 'false'. but physically i can found matched result for given id. here is UI

Guys i`m new to Delphi language.

1 Answer

You're not returning a value from your FindValueExists function, so you have absolutely no way of knowing if it locates the record or not. If you'd turn on compiler hints and warnings, the compiler would have pointed that fact out to you. (It would have informed you function findValueExists might not return a value, and also that Value assigned to 'state' is never used.)

Change your findValueExists so that it actually returns the result of the Locate call.

function TForm4.findValueExists(id: Integer): Boolean; begin Result := DBGrid1.DataSource.DataSet.Locate('code', id, []); end;