Creating a Databound Drop Down List in Oracle JDeveloper 10g
Written by Duncan Mills, Oracle Corporation
April 2004
Introduction
In a Struts / JSP application JDeveloper 10g provides a simple way
of creating bound input forms, allowing you to drag the basic form from the relevant
collection in the data control palette. Furthermore you can render individual
input fields in a variety of ways, in this case we'll look at creating a databound
drop down list step by step.
In this example we'll be using a screen created with a basic input form based
on the Employees table from the Oracle standard HR demo schema. The model project
for this example uses ADF Business Components to expose record collections for
the Employees (the basis of the form), and a second record collection containing
all Departments which will be used to populate the pop-list.
So in this tip we'll go through the steps required to replace the circled Department
ID number field with a bound drop down list that contains the names of all the Departments and populates the underlying attribute in the employees table.
Steps to Create the Databound Pop List
Delete the existing field (This can just be done in the JSP visual editor).
Open the Data Control palette, expand the EmployeesView collection
and select the DepartmentId attribute. In the Drag and Drop
As selection list at the bottom of the Data Control Palette select the
control type Single Select List.
Drag the selected DepartmentId attribute from the palette into the
space vacated by the DepartmentID field that you have just deleted. You
should see it dropped as a pop-list widget.
Now click on the UI Model Tab ( )
of the Structure Pane on the page you will see the following structure:
Notice the DepartmentId1 attribute at the bottom of this list - this is
the binding for new list item that you just created.
Double click (or choose Edit from the context menu) on this new binding.
The List Binding Editor will appear:
Use the List Binding Mode: list at the top of the dialog
to change the mode to LOV Mode:
This dialog has a Source Data Collection which will be a record collection
(e.g. a Business Components View Object) which will provide the valid list
of values. The Target Data Collection is pre selected and represents
the data collection that the input form is based on.
So the next task is to create a source iterator on the source collection
for the list. Expand the data control and select the correct collection. In
this case there is a View Object DepartmentsListView already set up:
Press the New button to create a new LOV Source iterator, accept
the default name:
Set the Select LOV Source Iterator drop down to this new
iterator (DepartmentsListViewIterator), the Add button on the dialog will
then enable. Press the Add button and set the join attributes (i.e.
DepartmentId = DepartmentId). Your dialog should now look like this:
The next step is to define what data the pop-list should display, click
the LOV Display Attributes tab on the dialog and shuttle
the DepartmentName field into the Attributes to Display list:
The drop down list is now ready to run, but if you do so you will notice that only the first 10 records in the department list are shown. This is default iterator range size used when you created the DepartmentsListViewIterator. In most cases you'll want to change this range size to cause all records to appear in the list. To make this change, click on the UI Model Tab ( ) of the Structure Pane again and select the DepartmentsListViewIterator in the structure. Bring up the property inspector if it is not visible and change the Range Size property from the default value of 10 to the value -1 which will cause all records to be displayed.
The setup of the pop-list is now all complete, and when run, the Data Page
will look like this:
Summary
List bindings provide a essential tool in building effective user interfaces, and are simple to implement in a declarative manner. Although the example shown here has been concerned with creating a list binding for drop down lists, the same method is used to create bindings for other list selection User interfaces such as T-Lists, radio groups, and check box groups. For a larger range of examples see the DataBound Lists using ADF sample on OTN (http://otn.oracle.com/sample_code/products/jdev/index.html), which provides a workspace containing several different list binding implementations.
The basic technique shown for creating a list binding is also applicable for use with alternative user interface technologies in ADF such as ADF UIX or ADF JClient. In both cases the user interface elements bound to the list bindings will be different, but the creation of the actual binding is identical.
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of the Structure Pane on the page you will see the following structure:
