ProviderBeforeGetRecords (Delphi)

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Description

 can create instances of the class. }
 RDMFactory: TComponentFactory;

implementation

{$R *.dfm}

{ Since this is a stateless server, before records are fetched, the query needs

 to be positioned to the correct location. The client passes the query and the
 value of the first field for the last record it fetched. If you are fetching
 all records, then you do not need to locate the last record. If the query
 is not changing, then you do not need to pass the query to the server.}

Code

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  ComServ, ComObj, VCLCom, StdVcl, ActiveX, DataBkr, Server_TLB,
  Db, DBTables, Provider, Variants;

type
  TPooledRDM = class(TRemoteDataModule, IPooledRDM)
    Session1: TSession;
    Database1: TDatabase;
    Query1: TQuery;
    DataSetProvider1: TDataSetProvider;
    procedure DataSetProvider1BeforeGetRecords(Sender: TObject;
      var OwnerData: OleVariant);
  protected
    class procedure UpdateRegistry(Register: Boolean; const ClassID, ProgID: string); override;
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
{
This example shows the implementation of a provider BeforeGetRecords
event handler and a RemoteDataModule UpdateRegistry method. The
complete project using this code example is in
Demos/DelphiWin32/VCLWin32/MIDAS/Pooler.
procedure TPooledRDM.DataSetProvider1BeforeGetRecords(Sender: TObject;
  var OwnerData: OleVariant);
begin
  try
    Query1.Close;
    Query1.SQL.Text := OwnerData[0];
    if not VarIsNull(OwnerData[1]) and not VarIsEmpty(OwnerData[1]) then
    begin
      Query1.Open;
      if not Query1.Locate(Query1.Fields[0].FieldName, OwnerData[1], []) then
        raise Exception.Create('Record not found');
      Query1.Next;
    end;
  finally
    OwnerData := NULL;
  end;
end;

Uses

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