[Overview][Constants][Types][Classes][Procedures and functions][Variables][Index] Reference for unit 'DB' (#fcl)


[Properties (by Name)] [Methods (by Name)] [Events (by Name)]

Data event handling agent for controls


Source position: db.pas line 1785

type TDataLink = class(TPersistent)


  constructor Create;


Initialize a new instance of TDataLink

  destructor Destroy; override;


Remove an instance of TDatalink from memory

  function Edit;


Set the dataset in edit mode, if possible

  procedure UpdateRecord;


Called when the data in the dataset must be updated

  function ExecuteAction(); virtual;


Execute action

  function UpdateAction(); virtual;


Update handler for actions

  property Active: Boolean; [r]


Is the link active

  property ActiveRecord: Integer; [rw]


Currently active record

  property BOF: Boolean; [r]


Is the dataset at the first record

  property BufferCount: Integer; [rw]


Set to the number of record buffers this datalink needs.

  property DataSet: TDataSet; [r]


Dataset this datalink is connected to

  property DataSource: TDataSource; [rw]


Datasource this datalink is connected to

  property DataSourceFixed: Boolean; [rw]


Can the datasource be changed

  property Editing: Boolean; [r]


Is the dataset in edit mode

  property Eof: Boolean; [r]


  property ReadOnly: Boolean; [rw]


Is the link readonly

  property RecordCount: Integer; [r]


Number of records in the buffer of the dataset





Data event handling agent for controls






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 .

See also



Base class for records-based data-access



Component representing the link between a local (GUI) component and a dataset



Represents the link between a detail data source and a master datasource.



Datalink for Master-Detail relationships between datasets.

Documentation generated on: May 14 2021