TDBLookupListBox class

In unit DBCtrls

Implements a data-aware listbox control with database lookup capabilities.

Declaration

pascal

TDBLookupListBox = class(TCustomDBListBox)

Inheritance

Description

TDBLookupListBox is a TCustomDBListBox descendant which implements a data-aware listbox with database lookup capabilities.

TDBLookupListBox allows selection of a value from a list of items, and stores the value to a field in a linked dataset. The database lookup feature allows a separate dataset to be used which contains the values for the items available in the control. Individual fields can be specified for both the stored value and the associated display value. Internally, it uses a TDBLookup component to enable the database lookup feature.

In addition, the control can be used in an unbound mode where either the DataSource or the DataField is not defined for the control. This allows the lookup dataset to synchronized when the current selection in the control is changed, but prevents the selected value from being stored in the linked dataset.

Use ListSource to provide access to the lookup dataset used in the control. Use ListField or ListFieldIndex to specify the field name or ordinal position in the lookup dataset displayed in the listbox. Use KeyField to specify the field name in the lookup dataset with the value stored in the DataField for the control. Use KeyValue to read or write the value for the KeyField in the lookup dataset.

Properties

`KeyValue`	public	Accesses the value for the KeyField in the lookup dataset.
`Align`	published	Specifies the placement of the control on its Parent control.
`Anchors`	published	The set of anchor definitions for this control.
`BiDiMode`	published	Indicates whether text controls use in bi-directional reading.
`BorderSpacing`	published	Determines the inner and outer border spacing for this control.
`BorderStyle`	published	Indicates the border style displayed around the control.
`Color`	published	The background color for the control.
`Constraints`	published	Contains the minimum and maximum Width and Height for the control.
`DataField`	published	Name for the field in the linked dataset used in the control.
`DataSource`	published	Provides access to the linked dataset for the control.
`DoubleBuffered`	published	When enabled, it reduces flicker when the control is painted.
`DragCursor`	published	The cursor shape shown during a drag operation.
`DragKind`	published	Indicates the action performed for a drag operation: drag-and-drop or drag-and-dock.
`DragMode`	published	Determines how a drag operation is started for the control.
`Enabled`	published	Determines whether the control responds to mouse or keyboard input.
`Font`	published	The font to be used for text display in this control.
`KeyField`	published	Field name in the lookup dataset with the value for the control.
`ListField`	published	Field name with the descriptive value displayed in the listbox.
`ListFieldIndex`	published	Ordinal position of the field in the lookup dataset with the descriptive value displayed in the control.
`ListSource`	published	Datasource with the lookup dataset for the control.
`LookupCache`	published	Indicates if caching is enabled for fields in the lookup dataset.
`NullValueKey`	published	Keyboard shortcut used to assign the empty key value to the control.
`EmptyValue`	published	Value used as the empty field value in the DataField for the control.
`DisplayEmpty`	published	Descriptive text displayed for the EmptyValue in the control.
`Options`	published	Contains options enabled for the list box control.
`ParentBiDiMode`	published	Indicates whether the BiDiMode settings in the Parent control are used.
`ParentDoubleBuffered`	published	Value for the DoubleBuffered property in a Parent control.
`ParentShowHint`	published	If True, the value of ShowHint for the control will be the same as the one from the Parent. Default is True.
`PopupMenu`	published	A context-sensitive menu that pops up when the right mouse button is clicked over this control.
`ReadOnly`	published	Indicates if the linked dataset for the control cannot be modified.
`ScrollListDataset`	published	Indicates if the look-up data set is scrolled for a new value in the control.
`ShowHint`	published	Enables Hint display for the control.
`Sorted`	published	Determines whether the list entries are sorted in alphanumeric order.
`TabOrder`	published	Indicates the navigation order for the control when the user presses the Tab or Shift+Tab key.
`TabStop`	published	Allows the user to navigate to / from the control by pressing the Tab or Shift+Tab keys.
`TopIndex`	published	Index of the first visible (or top-most) item.
`Visible`	published	Allows the control, and all of its children, to be displayed or hidden.

Methods

`DataChange`	protected	Performs actions needed when a new DataField value is selected using the lookup dataset.
`DoSelectionChange`	protected	Performs actions needed when the selected item in the listbox is changed.
`InitializeWnd`	protected	Initializes the window handle for the control.
`DestroyWnd`	protected	Frees the window handle and updates the address used for the Items in the controls.
`KeyDown`	protected	Applies the specified virtual key code to the control.
`Loaded`	protected	Performs actions needed when the control has loaded using the LCL streaming mechanism.
`UpdateData`	protected	Updates the data in the lookup dataset for the control.
`IsUnbound`	protected	Indicates if the control is being used in the "unbound" mode.
`Create`	public	Constructor for the class instance.

Events

`OnClick`	published	Notification handler for mouse clicks.
`OnContextPopup`	published	Invoked when a context-sensitive pop-up menu is requested.
`OnDblClick`	published	Event handler signalled when a mouse double click occurs in the control.
`OnDragDrop`	published	Event handler signalled when an object is dropped onto the control.
`OnDragOver`	published	Event handler signalled when a control is dragged over the control instance.
`OnEditingDone`	published	Event handler signalled when editing is completed for the control.
`OnEndDrag`	published	Event handler signalled for the end of a drag-drop operation.
`OnEnter`	published	Event handler signalled when the control receives focus.
`OnExit`	published	Event handler signalled when the control loses focus.
`OnKeyPress`	published	Event handler signalled for character data entered by the user.
`OnKeyDown`	published	Event handler signalled for key down keyboard events.
`OnKeyUp`	published	Event handler signalled when a key up event has occurred for the control.
`OnMouseDown`	published	Event handler signalled when a mouse down event is handled for the control.
`OnMouseEnter`	published	Event handler signalled when the mouse pointer has entered the control.
`OnMouseLeave`	published	Event handler signalled when the mouse pointer has left the control.
`OnMouseMove`	published	Event handler signalled when the mouse pointer is moved in the control.
`OnMouseUp`	published	Event handler signalled when a mouse up event is handled for the control.
`OnMouseWheel`	published	Event handler for mouse wheel turned.
`OnMouseWheelDown`	published	Event handler signalled for a downward movement of the mouse wheel.
`OnMouseWheelUp`	published	Event handler signalled for an upward movement of the mouse wheel.
`OnResize`	published	Notification handler for a resize of the control.
`OnStartDrag`	published	Event handler signalled for the start of a dragging operation.
`OnUTF8KeyPress`	published	Handler for a character entered by the user.