TDataSource¶
Component representing the link between a local (GUI) component and a dataset.
Declaration¶
Source position: db.pas line 2126
type
TDataSource = class(TComponent)
public
constructor Create;
destructor Destroy;
procedure Edit;
function IsLinkedTo : Boolean;
property State: TDataSetState; {r}
published
property AutoEdit: Boolean; {rwd}
property DataSet: TDataSet; {rw}
property Enabled: Boolean; {rwd}
property OnStateChange: TNotifyEvent; {rw}
property OnDataChange: TDataChangeEvent; {rw}
property OnUpdateData: TNotifyEvent; {rw}
end;
Inheritance¶
Description¶
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.
Properties¶
| Member | Visibility | Description |
|---|---|---|
| AutoEdit | published | Should the dataset be put in edit mode automatically. |
| DataSet | published | Dataset this datasource is connected to. |
| Enabled | published | Enable or disable sending of events. |
| State read only | public | State of the dataset. |
Methods¶
| Member | Visibility | Description |
|---|---|---|
| Create | public | Create a new instance of TDatasource. |
| Destroy | public | Remove a TDatasource instance from memory. |
| Edit | public | Put the dataset in edit mode, if needed. |
| IsLinkedTo | public | Check if a dataset is linked to a certain dataset. |
Events¶
| Member | Visibility | Description |
|---|---|---|
| OnDataChange | published | Called whenever data changes in the current record. |
| OnStateChange | published | Called whenever the state of the dataset changes. |
| OnUpdateData | published | Called whenever the data in the dataset must be updated. |