ADF : Making three level dependent LOV (List Of Values)

Hello all,

During the development we often come across a scenario in which we need to filter the List Of Values dependent on other List Of Values. Suppose you want only the cities of the selected country.

Here am about to show how we can make a three level dependent ListOfValues.
I will make a LOV which the user will select a location from locationLOV , then the other departmentLOV will show the department of the selected location, then the user will select a department and the employeeLOV will show the Employees of the selected department.

So, I have created an ADF application and made a connection to HR Schema. Also created three viewObject LovDepartmentVO,LovLocationsVO and LovEmployeeVO to make LOV's.

Now our main purpose is to filter the department on the basis of locations and employees on the basis of department.

For that we have to create a viewCritria in DepartmentsVo to filter departments on the basis of locations.

And then create view criteria for EmployeesVO.

Now we have viewObjects for LOV ready, we need to make a viewObject on whose attributes we will put these lovs.

So here I am creating a query from dual.
And then add three transient attributes as location , department and employees.
Make sure that property "updatable" is true.

Select locationsTrans and go to List of Values and add the lov by selecting LovLocationsVO.
Select departmentTrans and make a lov from lovDepartmentsVO.
Now go to view Accessors tab of the TemporaryVO you will see the lovs added to temporaryVO, now select the lovDepartment and click on edit button.

Select the viewCritera and in the bind value parameters select locationsTrans as value. This will filter the departments Lov on the basis of selecetd location.

Now add the lov on employeesTrans too and then go to viewAccessors select and mapp the bindVarible value to departmentTrans.

Now create am Applicaiton Module and add temporaryVo to AM and create a page and drag all the three attributes in the page and run the application.

Run the page and Select LocationTrans as London, then you will see DepartmentTrans filtered and you will see only 'Humar Resource' department in the lov as it resides in London. And in EmployeeTrans you will see Employees of Selected  department.

Make sure that the all the attribute have their autosubmit attribute to 'true' and attributes are partial trigged on basis of the source.

And the most important thing is that this technique will work on when the three attributes are on the same viewObject.. like in this case is the TemporaryVO.

You can Download the sample from here DependentLovTest.jar

If you have any questions regarding this, feel free to ask.

ADF : How ViewObjects (VO) get executed ? | View Object LifeCycle

View Objects are esssential part of ADF Business Components . These are associated with represention of DataSet.
ViewObjects contains a Query which when executed returns a set of results in form of rows. Then the view Object convert the rows returned from the query to ADF undestandable form i.e. ViewObjectRowImpl form.

So, the question is what happens when a viewObject gets a call?

ViewObject goes through a series of methods before representing a dataset. In other words we can name it ViewObject LifeCycle .

LifeCycle

When a viewObject is called the following methods are executed in the given sequence.

• At first when the viewObject is first executed the method first called in the ViewObjectImpl is
  executeQueryForCollection(Object qc, Object[] params, int noUserParams)
  This method executes the Database Query in the viewObject and then calls the next method.


• After executeQueryForCollection is executed then method hasNextForCollection(Object qc) is called. This method checks if the collection returned have a row or not. If hasNextForCollection(Object qc) returns True then the next method of the lifeCycle is called which converts the row to ADF understandable form i.e. into ViewObjectRowImpl from.


• So when method hasNextForCollection retuns true then method createRowFromResultSet(Object qc, ResultSet resultSet) is called and this method converts the row into ADF understandable form.


• This goes on until all the rows are covered and there is no rows left in collection. When there are no rows in the collection then the method hasNextForCollection returns false .


• Then method setFetchCompleteForCollection(java.lang.Object qc,boolean val) is called and it sets the flag for fetch completion. This indicates that the rows from the collection are fetched.

Here is a diagrammatic representation of ViewObject LifeCycle .

ADF : Refresh issues in Oracle ADF Application

During the application development in ADF, the most common problem that we encounter when our application is deployed on server is the problem of refresh. That means you expect a component to refresh on some action but still it doesn't happens.

This problem comes into picture in a big size application that uses many other applications or many taskflows are being called into it.I dont exaclty know why this problem comes into focus, but its some kind of 'id' problem of UIcomponent. 

So, here are some of the solution if the above problem comes into picture.

1. The easiest way to give partial trigger to a UIComponent is to go into the properties menu in the property inspector and simply choose the component id you want to select. So whenever the selected UIcomponents will have a change, the UIComponent on which partial refresh is given is refreshed.
   
   
   
   
   
   
   
    
2. Sometimes it happens that even after giving partial trigger on the UIComponent the Component is not been refreshed.So, you can try to refresh the component from the bean using java code.

   AdfFacesContext.getCurrentInstance().addPartialTarget(UIComponent);

   
   
   Here 'UIComponent' is the binding of the UIComponent on the page into the bean.
3. Sometimes the above two methods fail.After using the above two techniques also the field is not being refreshed. Then you can use the ResetUtil class for resetting the fields.
   
   For using ResetUtil you have to import the given class:

   import oracle.adf.view.rich.util.ResetUtils;
   

   
   And to use it on the page :
   
   

   ResetUtils.reset(UIComponent); 

4. After using the above methods if Still the problem exists. Then if you are using model in your application, then you have to perform "execute" on the used ViewObject.
5. Still if the problem persists, then perform "Rollback" after the "Commit" operation.
6. Still if the problem exists, please drop your case in the comment box.. :) 

Code to find an UI Component in an Oracle ADF Application

## Find an UI Component in the page

Hello all,
There are cases where you have to find a component on Page by id in the bean. Here is the method.


private UIComponent findComponentOnPage(String id){    

    String comp = id;

   //see ADF Code Corner sample #58 to read about the code

//used in the search below

FacesContext fctx = FacesContext.getCurrentInstance();

UIViewRoot root = fctx.getViewRoot();            

   root.invokeOnComponent(fctx,comp,

new ContextCallback(){

      public void invokeContextCallback(FacesContext facesContext,UIComponent uiComponent) {

       lookupComponent = uiComponent;

     }         

  });

return lookupComponent;

}

ADF: Code to use rowIterator

Hi,
Here is the method to use iterator in ADF Applications.

1)To get iterator object populated with the view rows

RowsetIterator itr=view.createRowsetIterator(null);

*dont use view.getIterator

2)To iterate within the iterator

itr.hasNext();
its.next();

If you have any questions regarding this or in ADF. I will be happy if i can help. :)

ADF: Code to validate duplicate record in Java Bean.

Hi,

Here am posting the code for applying Duplicate validation in ADF Applications through Java Bean. This can be used to check duplicate records in the oracle ADF Application.

    public void empIdValidator(FacesContext facesContext, UIComponent uIComponent, Object object) {
        if (object != null) {
            // 'am' is the applcation module
            ViewObjectImpl vo = am.getVo();
            // To get current Row off the Vo
            Row cRow = vo.getCurrentRow();
            // Create a Iterator to Iterate Over the ViewObject Vo
            // There is a also a method called vo.getRowSetIterator() but it is advised to use vo.createRowSetIterator(null)
            Integer count = 0;
            RowSetIterator rsi = vo.createRowSetIterator(null);
            while (rsi.hasNext()) {
                Row rw = rsi.next();
                if (rw != cRow) {
                    if (rw.getAttribute("EmpId") != null) {
                        Integer empId = (Integer) rw.getAttribute("EmpId");
                        if (empId = (Integer) object) {
                            count = 1;
                        }
                    }
                }
            }
            // Closing the iterator is advised after the use
            rsi.closeRowSetIterator();
            if (count == 1) {
                FacesMessage message2 = new FacesMessage("Duplicate EmpId !");
                message2.setSeverity(FacesMessage.SEVERITY_ERROR);
                throw new ValidatorException(message2);
            }
        }
    }

If you have any Questions regarding the above code. Feel free to ask. :)