Datasnap.DBClient.TCustomClientDataSet.SetOptionalParam

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Delphi

procedure SetOptionalParam(const ParamName: string; const Value: OleVariant;  IncludeInDelta: Boolean = False); virtual;

C++

virtual void __fastcall SetOptionalParam(const System::UnicodeString ParamName, const System::OleVariant &Value, bool IncludeInDelta = false);

Properties

Type Visibility Source Unit Parent
procedure
function
public
Datasnap.DBClient.pas
Datasnap.DBClient.hpp
Datasnap.DBClient TCustomClientDataSet

Description

Saves a custom parameter with the data packet.

You can add custom information to a data packet using the SetOptionalParam method. This information is saved with the data packet when it is saved to a file or stream, and copied with the value of the Data property. For example, by setting a parameter in the OnGetData event of the provider, application servers can include custom information with the data that is sent to client applications. Call GetOptionalParam to retrieve the custom information from the data packet.

The ParamName parameter specifies the name under which the custom information is stored. It can be any value except one of the following:


UNIQUE_KEY

DEFAULT_ORDER

CHANGE_LOG

SERVER_COL

CONSTRAINTS

DATASET_CONTEXT

DATASET_DELTA

LCID

BDERECORD_X

TABLE_NAME

MD_FIELDLINKS

UPDATEMODE


The Value parameter is an OleVariant that represents the custom information.

The IncludeInDelta parameter specifies whether the parameter is also stored with the Delta property. By including the parameter in the Delta property, it is sent along with updates to the provider. The provider can then retrieve this information using the GetOptionalParam method of the client dataset passed as a parameter to an OnUpdateData event handler.

Note: Do not confuse the optional data saved by this method with the Params property.

See Also