TcxDBComboBox Class
A data-aware combo box.
Declaration
TcxDBComboBox = class(
TcxCustomComboBox
)Remarks
A data-aware combo box allows you to display and edit values stored in a database. A combo box editor combines a single-line text editor and a drop-down menu. The drop-down menu displays a list of text strings accessible through the Properties.Items property. If user input in the text edit box matches initial characters in a menu string, the combo box allows a user to autocomplete the current input with the full string.
End-User Input Options
Up and Down arrow keys allow users to switch between combo box items, even when the drop-down menu is closed. Ctrl+PageUp and Ctrl+PageDown keystrokes select first and last items, respectively.
Drop-Down Menu Interaction
Users can do the following to open or close the drop-down combo box menu:
- Click the drop-down button.
- Focus the combo box and press the Alt+Up Arrow or Alt+Down Arrow key combination.
- Focus the combo box and press the F4 key.
Note
You can invoke the drop-down menu only if it contains at least one value.
Main API Members
The list below outlines key members of the TcxComboBox class that allow you to configure combo boxes and manage combo box items.
Appearance and Behavior Settings
- BeepOnEnter
- Specifies if the combo box plays the default system sound when a user confirms input.
- Style | StyleDisabled | StyleFocused | StyleHot | StyleReadOnly
Allow you to define individual appearance settings for different editor states.
Tip
To apply the same style settings to multiple editors, use a TcxEditStyleController component. If you need to apply the same style settings to all editors in your application, you can use a TcxDefaultEditStyleController component.
- Styles
- Provides access to individual styles applied to the combo box in different states.
Content-Related APIs
- Clear | EditingValue | EditValue | EditingText | EditText | ResetEditValue
- Manage the edit value.
- CopyToClipboard | CutToClipboard | PasteFromClipboard
- Allow you to perform clipboard operations.
- CanDropDown | DroppedDown | CloseUp
- Manage the drop-down menu.
- ItemIndex
- Specifies the active combo box item.
- OnEditing
- Allows you to prevent users from activating the combo box.
- PopupWindow
- Allows you to access and customize the drop-down menu.
- ResetEditValue
- Restores the previous edit value before the pending change is applied.
- SelectAll
- Selects editor content.
- SelStart | SelLength | SelText | SetSelection | SelectAll | ClearSelection
- Manage content selection.
- TextHint
- Specifies a text hint for the combo box when it has no assigned edit value.
- Undo
- Discards the last content change when the combo box has focus.
- ValidateEdit
- Validates the display value.
Data-Related APIs
- CanPostEditValue
- Identifies if the data-aware combo box can post its edit value to the bound data storage.
- DataBinding
- Allows you to bind the combo box to data.
- OnPostEditValue
- Executes custom code when the editor posts its value to the bound data storage.
- PostEditValue
- Posts the edit value to the bound data storage.
Combo Box Settings and Repository Items
- ActiveProperties
- Provides access to the current combo box settings regardless of their source. This property set does not allow you to customize combo box settings.
- GetPropertiesClass
- Returns the actual editor settings type.
- Properties
- Allows you to customize combo box settings directly if the combo box does not have an assigned repository item.
- RepositoryItem
- Specifies a repository item as an external source of combo box settings. A repository item has priority over other combo box settings.
General-Purpose API Members
- Enabled
- Specifies if the combo box is enabled.
- CanModify
- Identifies if the combo box is in read-only mode.
- IsEditValidating | IsHiding | IsPosting
- Allow you to identify the current operation in the combo box.
- Width | Height
- Allow you to explicitly define combo box dimensions.
Repository Item Class
You can create a TcxEditRepositoryComboBoxItem component in an edit repository to store combo box settings and share them between multiple combo boxes.
Limitations
The data-aware combo box is designed as a standalone editor. You cannot use a TcxDBComboBox class instance as an in-place editor in container controls.