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


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

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


Source position: db.pas line 1900

type TDataSource = class(TComponent)


  constructor Create(); override;


Create a new instance of TDatasource

  destructor Destroy; override;


Remove a TDatasource instance from memory

  procedure Edit;


Put the dataset in edit mode, if needed

  function IsLinkedTo();


Check if a dataset is linked to a certain dataset

  property State: TDataSetState; [r]


State of the dataset


  property AutoEdit: Boolean; [rw]


Should the dataset be put in edit mode automatically

  property DataSet: TDataSet; [rw]


Dataset this datasource is connected to

  property Enabled: Boolean; [rw]


Enable or disable sending of events

  property OnStateChange: TNotifyEvent; [rw]


Called whenever the state of the dataset changes

  property OnDataChange: TDataChangeEvent; [rw]


Called whenever data changes in the current record

  property OnUpdateData: TNotifyEvent; [rw]


Called whenever the data in the dataset must be updated





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








TDatasource is a mediating component: it handles communication between any DB-Aware component (often edit controls on a form) and a TDataset instance. Any database aware component should never communicate with a dataset directly. Instead, it should communicate with a TDatasource instance. The TDataset instance will communicate with the TDatasource instance, which will notify every component attached to it. Vice versa, any component that wishes to make changes to the dataset, will notify the TDatasource instance, which will then (if needed) notify the TDataset instance. The datasource can be disabled, in which case all communication between the dataset and the DB-AWare components is suspended until the datasource is again enabled.

See also



Base class for records-based data-access



Data event handling agent for controls

Documentation generated on: May 14 2021