Fixed Delphi 2009 TClientDataSet locate method (filter) at widestring problem

I have fixed "Clientdataset can't locate TWideStringField" problem!

I find then problem at TExprParser! You solve the problem Step by Step .

• Add a new class inheritance from TClienDataSet

• override Locate Method!

function TBearClientDataSet.Locate(const KeyFields: string; const KeyValues: Variant; Options: TLocateOptions): Boolean;
begin
　DoBeforeScroll;
　Result := LocateRecord2(KeyFields, KeyValues, Options, True);
　if Result then
　begin
　　Resync([rmExact, rmCenter]);
　　DoAfterScroll;
　end;
end;

• Add private LocateRecord2--Copy From LocateRecord and Change TExprParser to TExprParser2
• Write TExprParser2

Some Code..

function TFilterExpr2.PutConstant(Node: PExprNode): Integer;
begin
　Result := 0;
　case Node^.FDataType of
　　ftString, ftFixedChar, ftGuid: Result := PutConstAnsiStr(AnsiString(Node^.FData));
　　ftWideString, ftFixedWideChar: Result := PutConstUnicodeStr(UnicodeString(Node^.FData));
..
end.


function TFilterExpr2.PutConstAnsiStr(const Value: AnsiString): Integer;
var
Str: AnsiString;
Buffer: array[0..255] of Byte;
begin
　if Length(Value) >= SizeOf(Buffer) then Str := Copy(Value, 1, SizeOf(Buffer) - 1)
　else Str := Value;
　FDataSet.Translate(PAnsiChar(Str), PAnsiChar(@Buffer), True);
　Result := PutConstNode(ftString, @Buffer, Length(Str) + 1);
end;

function TFilterExpr2.PutConstUnicodeStr(const Value: UnicodeString): Integer;
var buffer: array of word; Len : Integer;
begin
　 Len := Length(Value);
　SetLength(buffer, Len + 1);
　buffer[0] := Len * 2;
　if Value <> '' then Move(Value[1], Buffer[1], Len*2);
　Result := PutConstNode(TFieldType(ftUnknown), @buffer[0], (Len+1)*2);
　SetNodeOp(Result, 0, $1007);
end;