ADF: How to create SelectOneChoice based on values from a database table in ADF Web Application - Part1

Recently there was couple of questions in the OTN forum in regards to creating dropdown in the based on values from a table. I googled and couldn't find much results on this. So thought of adding here.

Normally when we need an LOV/dropdown in the page, it will be for an attribute in a VO. So we define the LOV for that attribute in the VO definition.

ex: We will create a DeptVO with DeptId and DeptName and use this VO to create LOV for the departmentId attribute of EmployeeVO.

What if we just need a dropdown in the page with the values coming from a database table.

ex:- Just show a dropdown with all the Department Names.

Option1 : You can create a DummyViewObject with needed attribute(s) and create an LOV on that attribute(s) using the DeptVO. [I prefer this approach. This approach is explained here ADF: How to create SelectOneChoice based on values from a database table in ADF Web Application - Part2]

Option 2:

• Create a Query based View Object DeptVO with DepartmentId and DepartmentName.
• You just drag the DeptVO as  a selectOneChoice into the page.
  
• Select the DepartmentName as the display attribute.
  
• Remove the value property and map it to a Managed Bean variable.
• Set autoSubmit to true.  (Only if you want to handle the Value Change event)
• Set the Unselected Label to whatever you want. (ex: ***Select a Value***)
  
• You need to select the 'Include No Selection' checkbox in the ViewObject definition.
  

This is good enough to show the dropdown in the page based on values from the database, without creating additional ViewObject.

Now to get the values in the valueChangeListener event, you can write the below code:

   public void valueChangeEvent(ValueChangeEvent valueChangeEvent) {  
     System.out.println("New Name : " + valueChangeEvent.getNewValue());  
     valueChangeEvent.getComponent().processUpdates(FacesContext.getCurrentInstance());   
     DCBindingContainer bindingContainer = (DCBindingContainer) BindingContext.getCurrent().getCurrentBindingsEntry();   
     DCIteratorBinding binding = bindingContainer.findIteratorBinding("DeptVO1Iterator");   
     Row newRow = binding.getCurrentRow();   
     System.out.println("New ID: "+newRow.getAttribute("DepartmentId"));   
   }  

If you want to get the selected value on the click of a button, you can just get it from the ManagedBean variable.

   public void buttonActionListener(ActionEvent actionEvent) {  
     System.out.println("New Name : " + this.lovValue);  
   }  

Sample application built using Jdev 12.1.3 can be found here.

Feel free to point out if anything is missing/wrong in this blog.