...
when this page renders, the letter B will be selected because it is the object inside the drop down's model.
-Igor
\[Taken from a wicket-user posting - [Gwyn|User__Gwynevans] 22:57, 9 Apr 2006 (BST)\] Wiki Markup
Customizing the display of choices
...
Suppose you have an HTML snippet
...
Code Block |
---|
SelectOption[] options = new SelectOption[] {new SelectOption("&", "AND"), new SelectOption("|", "OR")};
ChoiceRenderer choiceRenderer = new ChoiceRenderer("value", "key");
add(new DropDownChoice("connective", model, Arrays.asList(options), choiceRenderer));
|
The ChoiceRenderer
will use the value of the 'key'
property of SelectOption object in the 'value' attribute in the rendered HTML (e. g. 'key' property value will be used as the option id). The 'value'
property will be used as a display value for the given option. Your backing model must use SelectOption as compared to String in the simple example.
...
Note |
---|
See also the JavaDoc for the ChoiceRenderer. Another example of custom ChoiceRenderer can be found in the DropDownChoice component reference in the Wicket Library. |
...
Code Block | ||||
---|---|---|---|---|
| ||||
<form wicket:id="form"> <select name="PhoneVendor" wicket:id="phoneVendor"></select> <select name="PhoneModel" wicket:id="phoneModel"></select> </form> |
...
Update with FormComponentUpdatingBehavior
Code Block |
---|
private DropDownChoice _phoneModelDDC; private MyModel _myModel = new MyModel(); public MyPage(PageParameters parameters) { Form form = new Form("form", new CompoundPropertyModel(_myModel)); add(form); addPhoneVendor(form); _phoneModelDDC = addPhoneModel(form); } private void addPhoneVendor(final Form form) { ArrayList phoneVendors = new ArrayList(getMySession().getTerminalVendors()); form.add(new DropDownChoice("phoneVendor", phoneVendors) { /** * Whether this component's onSelectionChanged event handler should called using * javascript if the selection changes. * * @return True if this component's onSelectionChanged event handler should * called using javascript if the selection changes */ protected boolean wantOnSelectionChangedNotifications() { return true; .add(new FormComponentUpdatingBehavior() { } /** * Called when a option is selected of a dropdown list that wants to be * notified of this event. * * @param newSelection The newly selected object of the backing model */ protected void onSelectionChangedonUpdate(final Object newSelection) { String phoneVendor = (String) newSelectiongetFormComponent().getModelObject(); _myModel.setPhoneModel(null); // Reset the phone model when the vendor changes phoneModelDDC.setChoices(getTerminalsByVendor(phoneVendor)); } })); } private DropDownChoice addPhoneModel(Form form) { List list = Collections.EMPTY_LIST; String phoneVendor = _myModel.getPhoneVendor(); if (phoneVendor != null) { list = getTerminalsByVendor(phoneVendor); } DropDownChoice phoneModelDDC = new DropDownChoice("phoneModel", list) { protected boolean wantOnSelectionChangedNotifications() { return true; } }; form.add(phoneModelDDC); return phoneModelDDC; } |
...
Update using Ajax
Code Block |
---|
private DropDownChoice _phoneVendorDDC, _phoneModelDDC; private MyModel _myModel = new MyModel(); public MyPage(PageParameters parameters) { Form form = new Form("form", new CompoundPropertyModel(_myModel)); add(form); _phoneVendorDDC = getPhoneVendorDDC(form); _phoneModelDDC = getPhoneModelDDC(form); form.add(_phoneVendorDDC); form.add(_phoneModelDDC); } private DropDownChoice getPhoneVendorDDC(final Form form) { ArrayList phoneVendors = new ArrayList(getMySession().getTerminalVendors()); DropDownChoice phoneVendorDDC = new DropDownChoice("phoneVendor", phoneVendors); // Add Ajax Behaviour... phoneVendorDDC.add(new AjaxFormComponentUpdatingBehavior("onchange") { protected void onUpdate(AjaxRequestTarget target) { // Reset the phone model dropdown when the vendor changes _myModel.setPhoneModel(null); _phoneModelDDC.setChoices(getTerminalsByVendor(_myModel.getPhoneVendor())); target.addComponent(_phoneModelDDC); } }); return phoneVendorDDC; } private DropDownChoice getPhoneModelDDC(Form form) { List list = Collections.EMPTY_LIST; String phoneVendor = _myModel.getPhoneVendor(); if (phoneVendor != null) { list = getTerminalsByVendor(phoneVendor); } DropDownChoice phoneModelDDC = new DropDownChoice("phoneModel", list); phoneModelDDC.setOutputMarkupId(true); // Needed for Ajax to update it return phoneModelDDC; } |
...
Donohoe Digital example - Good example of how to use DropDownChoice. Includes complete code for a key/value select choice and a select choice list that acts as IChoiceRenderer.
Binding Map to DropDownChoice
Binding Map example - Code sample binding a Map to DropDownChoice to persist an Integer using JPA.
[Cássio Landim post in wordpress 12:00, 5 Feb 2010 (BST)].