RAD Studio VCL Reference
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Shares the data belonging to another client dataset.
procedure CloneCursor(Source: TCustomClientDataSet; Reset: Boolean; KeepSettings: Boolean = False); virtual;
virtual __fastcall CloneCursor(TCustomClientDataSet Source, Boolean Reset, Boolean KeepSettings = False);
Call CloneCursor to share the data belonging to another client dataset. Source indicates another client dataset whose data is to be shared.
Reset and KeepSettings determine how to set the values of the following properties and events:
Filter, Filtered, FilterOptions, and OnFilterRecord
If Reset and KeepSettings are both false, the values of the properties listed above are all set to match the source dataset.
If Reset is true, the properties listed above are all cleared.
If Reset is false and KeepSettings is true, the properties listed above are not changed. In this case, the application must ensure that existing indexes, providers, and so on are compatible with the cloned data.
After calling CloneCursor, the data for the client dataset is the same as the data for Source. Edits performed by either client dataset are reflected in the data of both datasets.
Delphi Examples:
{ This example shows how to use the BeforeGetRecords event handler (a TRemoteEventType value) to send the provider information it needs for incremental data fetching. Before fetching the next data packet, the client dataset packages up the key value of the last record so that the provider knows where to begin the next data packet. It also sends some application-specific information, which is stored in Memo1. This method is used to pass the sql statement and the value of the first field for the last record to the server so that the server can return the correct records. The complete project using this code example is in Demos/DelphiWin32/VCLWin32/MIDAS/Pooler. } procedure TForm1.ClientDataSet1BeforeGetRecords(Sender: TObject; var OwnerData: OleVariant); var LastValue: OleVariant; CDSClone: TClientDataSet; begin if ClientDataSet1.Active then begin CDSClone := TClientDataSet.Create(Form1); try CDSClone.CloneCursor(ClientDataSet1, True); { turn off FetchOnDemand so that the clone only fetches the last LOCAL record } CDSClone.FetchOnDemand := False; CDSClone.Last; LastValue := CDSClone.Fields[0].AsString; CDSClone.Close; finally CDSClone.Free; end; end else LastValue := NULL; OwnerData := VarArrayOf([Memo1.Lines.Text, LastValue]); end; procedure TForm1.Button2Click(Sender: TObject); begin ClientDataSet1.PacketRecords := StrToInt(Edit1.Text); ClientDataSet1.GetNextPacket; end;
Copyright(C) 2008 CodeGear(TM). All Rights Reserved.
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