ADF Basics: Using setActionListener in ADF, Set pageFlowScope parameter without writing code

This post is about using setActionListener tag in ADF, this tag provides a simpler way to set values of other objects and makes use of EL
See What docs says-

The setActionListener tag is a declarative way to allow an action source (<commandButton>, <commandLink>, etc.) to set a value before navigation. It is perhaps most useful in conjunction with the "pageFlowScope" EL scope provided by ADF Faces, as it makes it possible to pass details from one page to another without writing any Java code. This tag can be used both with ADF Faces commands and JSF standard tags. More generally, it can be used with any component at all that implements the standard ActionSource interface.

Memory Scope For ADF Managed Beans-As per Fusion Developer guide

Scope of managed bean is a very important aspect while developing applications, so it is necessary to clearly understand memory scope of managed bean-
As per Fusion Developer's Guide for Oracle Application Development Framework 11g Release 1 (11.1.1)-

Application Scope-

The application scope lasts until the application stops. Values that you store in a managed bean with this scope are available to every session and every request that uses the application.
Avoid using this scope in a task flow because it persists beyond the life span of the task flow.

Session Scope-

The session scope begins when a user first accesses a page in the application and ends when the user's session times out due to inactivity, or when the application invalidates the session.
Use this scope only for information that is relevant to the whole session, such as user or context information. Avoid using it to pass values from one task flow to another. Instead, use parameters to pass values between task flows. Using parameters gives your task flow a clear contract with other task flows that call it or are called by it. Another reason to avoid use of session scope is because it may persist beyond the life span of the task flow.

Pageflow Scope-

Choose this scope if you want the managed bean to be accessible across the activities within a task flow. A managed bean that has a pageFlow scope shares state with pages from the task flow that access it. A managed bean that has a pageFlow scope exists for the life span of the task flow.If another task flow's page references the managed bean, the managed bean creates a separate instance of this object and adds it to the pageFlow scope of its task flow.

View Scope-

Use this scope for managed bean objects that are needed only within the current view activity and not across view activities. It defines scope for each view port that ADF Controller manages, for example, a root browser window or an ADF region.
The life span of this scope begins and ends when the current viewId of a view port changes. If you specify view, the application retains managed bean objects used on a page as long as the user continues to interact with the page. These objects are automatically released when the user leaves the page.

Request Scope-

Use request scope when the managed bean does not need to persist longer than the current request.

Backing Bean Scope-

A backing bean is a convention to describe a managed bean that stores accessors for UI components and event handling code on a JSF page. It exists for the duration of a request and should not be used to maintain state.
Use this scope if it is possible that your task flow appears in two ADF regions on the same JSF page and you want to isolate each instance of ADF region.

Most Used Codes in ADF (Iterate over ViewObject, get Value from pageFlow Scope variable)

Iterate Over View Object-

Some times we need to iterate in table to check for some validation as we have  to check for duplicate record, we want to delete all data of table with one click.

then we have to get all rows of table- this is a very common use case in ADF, so you can use following snippet of code to do this

1. Using AllRowInRange method to get rows available in range

  ViewObject vo=am.getViewObject();


   // Get All Rows in range of ViewObject in an Array
    Row[] rArray=vo.getAllRowsInRange();
    
    //Loop over array of Rows
    for(Row r:rArray){

       /*your operation code*/

       }

2. Using RowSetIterator-

  ViewObject vo = this.getViewObject();
       
       //Create RowSetIterator
        RowSetIterator rsi = vo.createRowSetIterator(null);
       //Iterate Over this to get all rows
        while (rsi.hasNext()) {
            Row nextRow = rsi.next();
            
        }
        rsi.closeRowSetIterator();

Get Value from taskFlow parameter(Using pageFlow Scope)-

we can get value from TaskFlow parameter using pageflow scope and can use it in Our Bean.

Suppose we have defined a parameter in page to pass Session_Id.

We can get it using pageflow scope

Integer sessionId = Integer.parseInt(resolvEl("#{pageFlowScope.Session_Id}"));

 Code For resolvEl-

    public String resolvEl(String data) {
        FacesContext fc = FacesContext.getCurrentInstance();
        Application app = fc.getApplication();
        ExpressionFactory elFactory = app.getExpressionFactory();
        ELContext elContext = fc.getELContext();
        ValueExpression valueExp = elFactory.createValueExpression(elContext, data, Object.class);
        String Message = valueExp.getValue(elContext).toString();
        return Message;
    }