You can drag the Standard JavaServer Faces Dropdown List component
from
the Palette to the Visual Designer to create a Dropdown List (or combo
box) that enables the user to click a drop button and select
items from a list.
- This component is a JavaServer Faces reference implementation that cannot use themes. The Drop Down List component in the Basic category of the Palette does support themes and provides other features that improve ease of use.
A Dropdown List is a list of items that initially displays as a single item and, when clicked, drops down into a list of multiple items. Only one item can be selected at a time. Dropdown Lists are the same as combo boxes in Swing and Microsoft Windows, and are called select lists in HTML.
A Dropdown List is a composite component: the enclosing component (dropdown) manages the style and behavior of the list itself, and the inside component (dropdownSelectItems) is used to bind to the actual items in the list. A third, related component named dropdownDefaultItems is created for each Dropdown List component that you add to the page and contains an array of static default items for the list (item1, item2, item3). This last component is not one that you typically work with. You can see all these components in the Outline window after you add a Dropdown List to your page.
A Dropdown List renders as an HTML <select> tag with the size=1 attribute.
The value property of the Dropdown List is not rendered on the screen but is used when the form is submitted. The value property refers to the currently selected list element. The list displayed in the component is controlled by the dropdownSelectItems part of the component.
After adding a Dropdown List Component to a page, you can do a number of things with it:
- Select the component and drag it to another location on
the page.
- Drag a table from the Servers window and drop it on the
component, and then choose which data provider will fill the list with data from a column of the database table. You can refine this choice by right-clicking the component, choosing Bind to Data, and clicking the Bind to Data Provider tab in the dialog box that opens. For more information, see Binding a List Component to a Database.
- Select the component and edit its properties in the Dropdown
List property
sheet. Some typical properties you might set are:
- id. The name of the component. In the JSP file,
this name is the value of the component's id
attribute. In the page bean, this property's value is
the name of the HtmlSelectOneMenu object.
- value. You do not usually set this
property. The value property is not rendered on the screen,
but is used when the form is submitted to send the currently
selected list element. The list displayed in the component
is controlled by the dropdownSelectItems part
of the component, not by the value property. See Fill
List From Database below for a typical way to set the
dropdownSelectItems part of the component.
- id. The name of the component. In the JSP file,
this name is the value of the component's id
attribute. In the page bean, this property's value is
the name of the HtmlSelectOneMenu object.
- Right-click the component and choose one of the following
pop-up menu items:
- Edit Event Handler. Write code for one of the
following event handlers.
- validate. Opens the Java Editor with the
cursor positioned in the component's validate
method so you can insert code to validate the value
of the component.
- processValueChange. Opens the Java Editor
with the cursor positioned in the component's processValueChange
method so you can insert code that executes when the
value of this component changes (for example, the user
changes the value of another component that is controlling
the value of this component).
- validate. Opens the Java Editor with the
cursor positioned in the component's validate
method so you can insert code to validate the value
of the component.
- Bind to Data. Bind the component's
valueproperty to an object or to a data provider, as described in Bind to Data Dialog Box.
- Auto-submit on Change. Causes the form to be automatically submitted if the value of the component changes. Sets the component's JavaScript onclick property to
common_timeoutSubmitForm(this.form, 'component-id');. At runtime, this code causes the form to be automatically submitted if the user changes the component value. Once the form is submitted, conversion and validation occur on the server and any value change listener methods execute, and then the page is redisplayed.
A component configured to Auto-submit on Change can use virtual forms to limit the input fields that are processed when the form is submitted. If the auto-submit component is defined to submit a virtual form, only the participants in that virtual form will be processed when the auto-submit occurs.
- Configure Virtual Forms. Enables you to add the component to a virtual form.
- Property Bindings. Opens a dialog box that enables
you to bind the properties of the component to other objects
or properties that can update or evaluate this component's properties
automatically.
- Edit Event Handler. Write code for one of the
following event handlers.
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