Datasnap.DBClient.TCustomClientDataSet.BeforeGetParams
Delphi
property BeforeGetParams: TRemoteEvent read FBeforeGetParams write FBeforeGetParams;
C++
__property TRemoteEvent BeforeGetParams = {read=FBeforeGetParams, write=FBeforeGetParams};
Properties
| Type | Visibility | Source | Unit | Parent |
|---|---|---|---|---|
| event | protected | Datasnap.DBClient.pas Datasnap.DBClient.hpp |
Datasnap.DBClient | TCustomClientDataSet |
Description
Occurs before the client dataset fetches parameter values from the provider.
Write a BeforeGetParams event handler to send custom information to the client dataset's provider. BeforeGetParams is part of the mechanism by which a client dataset and a provider communicate information when passing parameter values from the provider's dataset. When working with a provider on a stateless application server, this mechanism allows the client dataset and the provider to communicate persistent state information.
When the application calls the client dataset's FetchParams method, the following events occur:
- The client dataset receives a BeforeGetParams event, where it can encode custom information into an OleVariant that is passed to the provider as the
OwnerDataparameter. - The provider receives a BeforeGetParams event, where it can respond to or change that information before it retrieves parameter values.
- The provider encodes all of its dataset's current parameter values into an OleVariant.
- The provider receives an AfterGetParams event, where it can encode custom information into its
OwnerDataparameter or respond to information from the BeforeGetParams event handler. - The client dataset unpacks the parameters from the provider into the Params property and then receives an AfterGetParams event, where it can respond to the custom information returned by the provider's AfterGetParams event handler.
BeforeGetParams is an event handler of type Datasnap.DBClient.TRemoteEvent.