TDataLink class

In unit DB

Data event handling agent for controls.

Declaration

pascal

TDataLink = class(TPersistent)

Inheritance

TDataLink
TPersistent
TObject

Descends from it: TComponentDataLink TDBNavDataLink TDetailDataLink TFieldDataLink

Description

TDataLink is used by GUI controls or datasets in a master-detail relationship to handle data events coming from a TDatasource instance. It is a class that exists for component programmers, application coders should never need to use TDataLink or one of it's descendents.

DB-Aware Component coders must use a TDatalink instance to handle all communication with a TDataset instance, rather than communicating directly with the dataset. TDataLink contains methods which are called by the various events triggered by the dataset. Inversely, it has some methods to trigger actions in the dataset.

TDatalink is an abstract class; it is never used directly. Instead, a descendent class is used which overrides the various methods that are called in response to the events triggered by the dataset. Examples are .

Properties

`VisualControl`	protected
`FirstRecord`	protected
`Active`	public	Is the link active.
`ActiveRecord`	public	Currently active record.
`BOF`	public	Is the dataset at the first record.
`BufferCount`	public	Set to the number of record buffers this datalink needs.
`DataSet`	public	Dataset this datalink is connected to.
`DataSource`	public	Datasource this datalink is connected to.
`DataSourceFixed`	public	Can the datasource be changed.
`Editing`	public	Is the dataset in edit mode.
`Eof`	public
`ReadOnly`	public	Is the link readonly.
`RecordCount`	public	Number of records in the buffer of the dataset.

Methods

`ActiveChanged`	protected
`CheckBrowseMode`	protected
`DataEvent`	protected
`DataSetChanged`	protected
`DataSetScrolled`	protected
`EditingChanged`	protected
`FocusControl`	protected
`GetActiveRecord`	protected
`GetBOF`	protected
`GetBufferCount`	protected
`GetEOF`	protected
`GetRecordCount`	protected
`LayoutChanged`	protected
`MoveBy`	protected
`RecordChanged`	protected
`SetActiveRecord`	protected
`SetBufferCount`	protected
`UpdateData`	protected
`Create`	public	Initialize a new instance of TDataLink.
`Destroy`	public	Remove an instance of TDatalink from memory.
`Edit`	public	Set the dataset in edit mode, if possible.
`UpdateRecord`	public	Called when the data in the dataset must be updated.
`ExecuteAction`	public	Execute action.
`UpdateAction`	public	Update handler for actions.

Inherited

From TPersistent (8)

Assign AssignTo DefineProperties FPOAttachObserver FPODetachObserver FPONotifyObservers GetNamePath GetOwner

From TObject (40)

AfterConstruction BeforeDestruction CheckDisposed ClassInfo ClassName ClassNameIs ClassParent ClassType CleanupInstance DefaultHandler DefaultHandlerStr Dispatch DispatchStr Disposed DisposeOf Equals FieldAddress Free FreeInstance GetDisposed GetHashCode GetInterface GetInterfaceByStr GetInterfaceEntry GetInterfaceEntryByStr GetInterfaceTable GetInterfaceWeak GetLastCastErrorInfo InheritsFrom InitInstance InstanceSize MethodAddress MethodName newinstance QualifiedClassName SafeCallException StringMessageTable SystemHasExtendedRTTI ToString UnitName

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.