Datasnap.Provider.TCustomProvider.BeforeRowRequest
Delphi
property BeforeRowRequest: TRemoteEvent read FBeforeRowRequest write FBeforeRowRequest;
C++
__property Datasnap::Dbclient::TRemoteEvent BeforeRowRequest = {read=FBeforeRowRequest, write=FBeforeRowRequest};
Properties
| Type | Visibility | Source | Unit | Parent |
|---|---|---|---|---|
| event | protected | Datasnap.Provider.pas Datasnap.Provider.hpp |
Datasnap.Provider | TCustomProvider |
Description
Occurs before the provider creates a delta packet with information about the current record.
Write a BeforeRowRequest event handler to respond to custom information from a client dataset. BeforeRowRequest is part of the mechanism by which a provider and a client dataset communicate information about data fetching. When the provider is part of a stateless application server, this mechanism allows the provider and the client dataset to communicate persistent state information.
When the client dataset fetches detail information about the current record or refreshes the current record, the following events occur:
1.The client dataset receives a BeforeRowRequest event, where it can encode custom information into an OleVariant.
2.The provider receives a BeforeRowRequest event, where the custom information appears as the OwnerData parameter. The provider can respond to or change that information before it looks up the requested information.
3.The provider creates a delta packet that contains the requested information.
4.The provider receives an AfterRowRequest event, where it can encode custom information into its OwnerData parameter or respond to information from the BeforeRowRequest event handler.
5.The client dataset receives an AfterRowRequest event, where it can respond to the custom information returned by the provider in its AfterRowRequest event handler.
BeforeRowRequest is of type Datasnap.DBClient.TRemoteEvent.