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Oracle® HTML DB
Release 2.0 |
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A list of values (LOV) is a static or dynamic set of values used to display a specific type of page item, such as popup lists of values, a select list, a check box, a radio group, or multiple select lists.
Topics:
You define named (or shared) LOVs at the application level by running the Create LOV Wizard and adding them to the List of Values repository. All LOVs can be defined as static or dynamic. Static lists are based on predefined pairs of display values and return values. Dynamic lists are based on a SQL query you write that selects values from a table.
To create a named LOV:
Navigate to the Workspace home page.
Click the Application Builder icon.
Select an application.
The Application home page appears.
Click the Shared Components icon.
Under User Interface, select Lists of Values.
To create a new LOV, click Create.
Follow the on-screen instructions.
New named LOVs are added to the List of Values repository.
Once you create a LOV, it appears on the List of Values page. You control how the page displays by making a selection from the View list. Available options include:
Icons (the default) displays each LOV as a large icon. To edit a LOV, click the appropriate icon.
Details displays each LOV as a line in a report. To edit a LOV, click the name.
Static LOVs are based on a static list of display values and return values you specify when you run the Create LOV Wizard. To create a static LOV, you run the Create LOV Wizard and select the LOV type Static. Oracle HTML DB stores the display values, return values, and sort sequence you specify in the List of Values repository. Once you add a static LOV to the repository, you can create an item and display it as a check box, radio group, select list, or popup list based on this definition.
To edit an existing LOV, select the LOV on the Lists of Values page.
To edit a LOV:
Navigate to the Workspace home page.
Click the Application Builder icon.
Select an application.
Click Shared Components.
Under User Interface, select Lists of Values.
Select an LOV.
The Edit List of Values page appears.
Edit the appropriate attributes and click Apply Changes.
You can edit the display values of all static LOVs by clicking the Grid Edit button on the Edit List of Values page.
To perform a bulk edit of static LOVs:
Navigate to the Workspace home page.
Click the Application Builder icon.
Select an application.
Click Shared Components.
Under User Interface, select Lists of Values.
By default, LOVs display as icons.
Change the default display. Select Details from the View list and click Go.
Locate Static LOV and select the LOV name.
Click the Grid Edit button located under Subscription.
Edit the appropriate display values and click Apply Changes.
You can reference session state by using bind variables. In the following example, this LOV only works if the item called my_deptno contains a valid department number.
SELECT ename, empno FROM emp WHERE deptno = :my_deptno
When you derive an item's source from an LOV and select a null value, if the null value specified by the developer in the item attributes is not a visible non-null text value, the value POSTed when the page is submitted is often the string %null% and not an Oracle null value.
Be aware of this behavior when writing code to evaluate submitted values. For example, suppose a page evaluates the submitted item P1_X and you need to use the PL/SQL expression replace(:P1_X,'%'||'null%',null) to prepare the item for permanent storage in session state or for passing to DML or other APIs.
To avoid problems, be aware of the appropriate way to code %null% in expressions that occur in page computations, processes, and validations. You must break up the string so that the application does not replace %null% with a null value in the page metadata when it is saved. Consider the following example:
'%'||'null%'
Application Builder includes a number of reports designed to help you better manage LOVs.
To access LOV reports:
Navigate to the Workspace home page.
Click the Application Builder icon.
Select an application.
When Application Builder appears, click Shared Components.
Under User Interface, select Lists of Values.
Select one of the following tabs at the top of the page:
Search
Subscription
Utilization
History
Follow the on-screen instructions.
Click Search to display the Search Dynamic Lists of Values page. Use this page to search the queries that makes up dynamic LOVs. Enter a query in the Query Contains field and click Go.
Click Subscription to display the List of Values Subscription page. This page displays all subscribed LOVs in your application.