Clientdataset 'index not found' error in nested dataset - delphi

Question

I am attempting to find a subset of records in a clientdataset by using a clone cursor to seek a records using an indexdef. In the example below I have created a button to implement the clone creation. The code works fine for a clientdataset named cdsData. However if I nest cdsData in another dataset (cdsMaster) then the button code fails to find the indexDef.
The Form: (including both clientdatasets showing both datasources and clientdatasets. Omit dsMaster & cdsMAster in first unit example below)
object Form1: TForm1
Left = 0
Top = 0
Caption = 'Form1'
ClientHeight = 289
ClientWidth = 554
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
OldCreateOrder = False
OnCreate = FormCreate
PixelsPerInch = 96
TextHeight = 13
object Button1: TButton
Left = 32
Top = 24
Width = 75
Height = 25
Caption = 'Clone'
TabOrder = 0
OnClick = Button1Click
end
object dsMaster: TDataSource
DataSet = cdsMaster
Left = 56
Top = 80
end
object cdsMaster: TClientDataSet
Aggregates = <>
Params = <>
Left = 56
Top = 144
end
object dsData: TDataSource
DataSet = cdsData
Left = 152
Top = 88
end
object cdsData: TClientDataSet
Aggregates = <>
Params = <>
Left = 152
Top = 144
end
end
The successful cdsData unit:
unit IndexFindTest;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Data.DB, Datasnap.DBClient;
type
TForm1 = class(TForm)
dsData: TDataSource;
cdsData: TClientDataSet;
Button1: TButton;
procedure FormCreate(Sender: TObject);
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
Disp, Lbl : string;
implementation
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
var
Clone: TClientDataset;
begin
Clone := TClientDataset.Create(nil);
try
Clone.CloneCursor(cdsData,false);
cdsData.IndexDefs.Update;
clone.IndexName := cdsData.IndexDefs.find ('Lbl').Name;
//..added code to select a range of records using the IndexDef
finally
clone.free;
end;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
disp := 'Item 1';
lbl := 'a';
with TStringField.Create(Self) do begin
Name := 'MstrDisplays';
FieldKind := fkData;
FieldName := 'Displays';
Size := 10;
DataSet := cdsData;
end;
with TStringField.Create(Self) do begin
Name := 'MstrLabel';
FieldKind := fkData;
FieldName := 'Label';
Size := 10;
DataSet := cdsData;
end;
with cdsData.IndexDefs.AddIndexDef do begin
Name := 'Lbl';
Fields := 'Displays;Label';
Options := [ixCaseInsensitive];
end;
cdsData.CreateDataSet;
end;
end.
The nested version that fails:
unit IndexFindTest2;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Data.DB, Datasnap.DBClient;
type
TForm1 = class(TForm)
dsMaster: TDataSource;
cdsMaster: TClientDataSet;
Button1: TButton;
dsData: TDataSource;
cdsData: TClientDataSet;
procedure FormCreate(Sender: TObject);
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
Disp, Lbl : string;
implementation
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
var
Clone: TClientDataset;
begin
Clone := TClientDataset.Create(nil);
try
Clone.CloneCursor(cdsData,false);
cdsData.IndexDefs.Update;
//Error generated in next line
clone.IndexName := cdsData.IndexDefs.find ('Lbl').Name;
//..added code to select a range of records using the IndexDef
finally
clone.free;
end;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
disp := 'Item 1';
lbl := 'a';
with TStringField.Create(Self) do begin
Name := 'MstrTitle';
FieldKind := fkData;
FieldName := 'Title';
Size := 10;
DataSet := cdsMaster;
end;
with TDataSetField.Create(Self) do
begin
Name := 'MstrDisplay';
FieldName := 'Displays';
DataSet := cdsMaster;
end;
cdsData.DataSetField := TDataSetField(cdsMaster.FieldByName('Displays'));
with TStringField.Create(Self) do begin
Name := 'ClientNested';
FieldKind := fkData;
FieldName := 'Notes';
Size := 10;
DataSet := cdsData;
end;
with TStringField.Create(Self) do begin
Name := 'kntLabel';
FieldKind := fkData;
FieldName := 'Label';
Size := 10;
DataSet := cdsData;
end;
cdsData.IndexDefs.Update;
with cdsData.IndexDefs.AddIndexDef do begin
Name := 'Lbl';
Fields := 'Notes;Label';
Options := [ixCaseInsensitive];
end;
cdsMaster.CreateDataSet;
end;
end.
When running the second program I receive the error
cdsData: index 'Lbl' not found.
The only difference I can identify between the two programs is the fact that cdsData is nested in the second version. I found a note in CaryJensen's Delphi in Depth:clientDatasets 2nd edition (pg128) stating that the erro may occur and can be fixed using update, but no matter where in the sequence I apply the update, it does not work in this situation.
Can anyone shed light on this problem? Are there additional steps with a nested dataset?