Exception handling within a value-binding expression

Hi all,
Forgive me if this question seems odd, but I am a long-time Struts developer, new to JSF.
In Struts, exception handling was easy because all requests were funnelled through some subclass of Action. Exception handling could effectively be consolidated into one spot by applying the template-method pattern.
Of course, with JSF, this is not possible because method names in value-binding and action-binding expressions can be chosen arbitrarily. For this reason, I am exploring aspect-oriented (and other) techniques for consolidation JSF exception handling into one spot, but rather than focus too intently on that, it's clear that I first need the ability to forward to an error page when an exception is encountered in a value-binding or action-binding expression.
For action-binding expressions, ExternalContext.dispatch("<view id>"); seems to work quite well, but I am unable to make the same work when in the context of a value-binding expression. This is probably attributed to the fact that at that point, I am in an entirely different phase of the JSF request processing lifecycle.
What I'm looking to know is if anyone has a reliable means of forwarding to an error page within the context of a value-binding expression. Better yet, does anyone know a reliable way of forwarding to another view regardless of what phase you are in?
If it makes a difference (and I think it does) the error page uses JSF as well, and uses the same layout (provided via custom tags courtesy of JSP 2.0 tag files), so some view components would have the same name as the page which encountered the error. This seems to get in the way of me simply defining the error page for a 500 in my web deployment descriptor.
Thanks in advance to anyone with a working suggestion.
-Kent

Let me pose a purely hypothetical use case to demonstrate the problem:
Imagine a page in an HR app, employeeDetails.jsp, that displays an always-up-to-date combo box which lists employee names and IDs. onChange triggers a form submit with the intention of simply posting back to this page, with various text boxes, etc. below updated to show all information for the selected employee.
Obviously, with the requirement that the combo box always be up to date, it's clear that the getter invoked by the value-binding expression must access the database (not directly of course, but via a facade, application, then data-access layer). Any unexpected and unchecked exception in this chain would propagate back up to the getter method on the backing bean. I need to, at that point, log the exception (trivial) and forward to a user-friendly error page.
I suppose I could put some contraint on myself that data access is only performed within ActionEvent handlers, but I'm not sure that's consistent with the JSF model in general, in fact it almost seems Struts-like in that I'd have to invoke some action before loading this form to build the up-to-date list for the combo box, shove it in request scope, where it's then available to the page indicated by the navigation rules. Submission of the form on the page in question would also need to result in rebuilding the up-to-date list. Now we're looking at firther propagation of code. I want to avoid this, so I am looking for a better way.

Similar Messages

Faces config exception - Can't get value from value binding expression:

the menuItem_Department shown property takes value from userRight's session bean object userDetail.
class UserRights{
    public boolean mDept = false;
    public boolean loggedIn = false;
    public boolean admin = false;
   //accessors
}now, the shown property picks correct value for #{userDetail.admin} but gives erros on this. any idea how to get around this exception:
Managedbean menuItem_Department could not be created Can't get value from value binding expression: '#{userDetail.mDept}'.
javax.faces.FacesException: Can't get value from value binding expression: '#{userDetail.mDept}'     at com.sun.faces.config.ManagedBeanFactory.evaluateValueBindingGet(ManagedBeanFactory.java:903)
     at com.sun.faces.config.ManagedBeanFactory.setPropertiesIntoBean(ManagedBeanFactory.java:547)
     at com.sun.faces.config.ManagedBeanFactory.newInstance(ManagedBeanFactory.java:233)
     at com.sun.faces.application.ApplicationAssociate.createAndMaybeStoreManagedBeans(ApplicationAssociate.java:256)
.. stack tracepointers appreciated.
reagrds
Rabs

well, i figured out the problem so thought to share with all aswell.
all i changed was the name of the variable from mDept to dept.
java beans has its own set of rules and naming conventions which i have not read much about but this problem had to do sumthing with that!
just changing the name simply works fine!

Using value binding expression for to-view-id

hi;
is it possible to use a value binding expression in the <to-view-id> element?
if not, is there a logical reason for this?
thanks

Shrek-2:
Are we there yet?No
Are we there yet?No
Are we there yet?Yes
Really?
NO
Seriously, the default navigation handler does not allow to use EL for the to-view-id, but you can obtain the desire behaviour with the custom handler decorator.
This is a code snippet:
     public void handleNavigation(FacesContext fc, String actionMethod, String actionName) {
          _base.handleNavigation(fc, actionMethod, actionName);
          String viewId = fc.getViewRoot().getViewId();
        if ((viewId.indexOf("#{") != -1) &&
                (viewId.indexOf("#{") < viewId.indexOf('}'))) {
             String bviewId = (String)fc.getApplication().createValueBinding(viewId).getValue(fc);
             if (bviewId != null)
                  fc.getViewRoot().setViewId(bviewId);
             else {
                  // you can throw the exception here
     }More about HandlerDecorator:
http://www.jsftutorials.net/jsfNavigation/jsf-login-navigation-redirect.html
http://www.jsftutorials.net/faces-config/navigationDecorator.html
P.S. Note: This feature might broke the separation between the different levels of application from the architectural point of view. Hard-coding the ViewIds inside the java code is not a good idea at all.
Sergey : jsfTutorials.net

Exception Handling Within Methods

I'm currently looking over exception handling within Java and have what whats probably a very simple question to answer!
If within a method I have a try and catch block to handle all exceptions that the specific method may throw, do I then also need to specify the exceptions that the method will throw within its signature? (As I have already handled them).

After a bit more reading I think i've found my answer.
You only declare a method throws an exception if you wish to deal with it further up the method call stack. This raises another question though. If I did handle the exceptions that my method could throw within the method itself as well as declaring the method to throw the exceptions within its signature. What would happen?

Using value binding expressions to set 'required' attribute

I am trying to use a value binding expression to determine whether the value of various input control's is required or not according to where they are used and not having much luck. I wonder if anyone can shed some light on this...
The following expression works: <h:inputText id="name" required="#{true}"/> whereas <c:set var="required" value="true" scope="request"/>
<h:inputText id="name" required="#{required}"/> does not, even though the expression evaluates to true! I have tried numerous variations (requestScope.required, required == true, required ? true : false, etc.) to no avail. Interestingly, #{1 == 1} or binding to a backing bean method works, but as soon as you add a request variable it breaks.
Am I doing something wrong, is this something that JSF doesn't allow, or just a bug in the RI? Note that I don't want to vary this flag between multiple submissions of the same form, I am just trying to reuse the same JSP include to generate form controls for required and optional data on different forms to avoid a whole lot of cutting any pasting.
Any pointers gratefully received.
-- Keith Wilson

I had something like this happen, and here's what I concluded the problem was. Perhaps your problem is similar.
In the first non-working example you show a request-scope variable being set in the JSP page, and then use that to set the "required" attribute. But consider what happens when you submit the form. There is no longer any request-scope variable set because we have a new request and we don't go through the JSP page! (Not before validation is checked, anyhow).
So basically I concluded that the variable had to be in (say) session scope for it to work as you would like.

Localized String with params - Value Binding Expression...

Hi All:
I see many e.g.s where a command button / or a label's value can be a localized resource string using the generic value binding expression:
"#{bundleVarName.keyName}"
what if the resource string has parameters? for e.g.
button.caption = Click Me for {0}
Can we assign a value binding expression with params for button captions etc.
Please help - I am a newbie in JSF,,,
regards
-Somesh

JSF developers have forgotten about this :)
Use other tools for displaying such messages (f. e. JSTL) where you need to have parametrized messaged.
But mostly, non-parameterized JSF will be enough.

Question on value binding

Hi I am trying to put 2 value binding statements into one method "ok()" in the backing bean. here they are.
     FacesContext context = FacesContext.getCurrentInstance();
     ValueBinding vb = context.getApplication().createValueBinding(
               "#{LoginBean.subject}" );
Subject subject = (Subject)vb.getValue( context );and
     FacesContext context = FacesContext.getCurrentInstance();
     ValueBinding vb = context.getApplication().createValueBinding(
          "#{UserGroupBrowserBean.selectedGroupName}" );
     vb.setValue( context, newGroup );This is giving me the error when i try to build it as follows:
"context is already defined in ok()" and "vb is already defined in ok()"
How do I fix this. how do i insert the second value binding expression in the method. any help hugely appreciated. 5DD's
thanks
joe

     ValueBinding vb0, vb1;
        FacesContext context = FacesContext.getCurrentInstance();
     Application ap = context.getApplication();
        vb0 = ap.createValueBinding("#{LoginBean.subject}" );
        Subject subject = (Subject)vb0.getValue(context);
     vb1 = ap.createValueBinding("#{UserGroupBrowserBean.selectedGroupName}");
     vb1.setValue(context, newGroup);Does your bean have proper setter/getter methods for them properties?

Binding expressions and collections

<quote>
In addition to being able to read the initial value of a field from an object, value binding expressions can also be used to navigate maps, lists, or arrays. Here are some examples:
#{foo[bar]}
#{foo["bar"]}
#{foo[3]}
#[foo[3].bar}
#{foo.bar[3]}
</quote>
Could anyone explain how does it work ? Is foo is always bean ?
Isn't #{foo["bar"]} identical to #{foo.bar}
Also in "Core JSF" they say #{foo.bar[3]} doesn't work if bar indexed property of a bean.
<anotherquote>
The syntax of a method binding expression has two primary formats:
#{expr-a.value-b}
#{expr-a[value-b]}
The first format is a classic DOM-style object tree structure. The second format can be used to call a method pointed to from an object array, Map, or List.
</anotherquote>
The same question how to use the second form.

An expression is a little piece of softwaremuch like a scriptthat evaluates to a single value for a single layer property at a specific point in time. Whereas scripts tell an application to _do_ something, an expression says that a property _is_ something.
With expressions, you can create relationships between layer properties and use the keyframes of one property to dynamically animate other layers. For example, you can use the pick whip to link path properties, so a mask can take its path from a brush stroke or a shape layer object.
The expression language is based on the standard JavaScript language, but you do not need to know JavaScript to use expressions. You can create expressions by using the pick whip or by copying simple examples and modifying them to suit your needs.
Be sure to read the
"Expressions" section of After Effects Help on the Web.
Dan Ebberts has an excellent collection of example expressions and scripts and tutorials for learning how to work with expressions and scripts on his website: http://www.adobe.com/go/learn_ae_motionscripthome.
The AE Enhancers forum provides many examples and much information about expressions, as well as scripts and animation presets: http://www.adobe.com/go/learn_ae_aeenhancershome.
JJ Gifford provides several example projects on his website that demonstrate how to use expressions: http://www.adobe.com/go/learn_ae_jjgiffordexpressions.

Dynamic value binding for InputTextField - Expression within an expression

Hi,
I have this requirement where I have to use an EL expression's output as a bean's property in the value attribute of a InputTextField. E.g.
          <h:dataTable value="#{entity.formats}" var="field">
               <h:column>
                    <h:outputLabel value="#{field.shortDesr}"/>
               </h:column>
               <h:column>
                    <h:inputText value="#{*entity."+#{field.shortDesr}+*"}"/>
               </h:column>
          </h:dataTable>
The JSF page will be a generic one so the fields within a form will be dynamic and will be formed at run-time. Since the exact bean property(entity in the code above) for a particular field is not known before, it needs to be dynamicaly built
To give more clarity. In the following snippet, i know that entity is the bean to be used but which property(XXX) the text field has to be bound is not known and needs to be assigned at run-time.
<h:inputText value="#{entity.*XXX*"/>
Is this possible? Are there any direct JSF solution or work arounds for it? Appreciate your inputs.
Thanks
Ranjith

A: Dynamic value binding for InputTextField - Expression within an expression

Hi BaluSC,
Your solution is totally acceptable. But I was also looking for something that can make possible direct binding to the bean properties without going through a Map.
In the meantime, I worked around the problem by not using the DataTable. Instead I loop the collection and add the Form elements programatically (code given below). With this I am able to achieve the desired effect of binding directly to the bean's property. But I am hitting another problem now, On submit the form Seam throws up 'No active conversational context" error while binding the #{sdmManager.grid} attribute. Now, I am trying to figure out how to come across it.
JSF
     <h:panelGrid columns="2" binding="#{sdmManager.grid}">
</h:panelGrid>
Bean code
     public HtmlPanelGrid getGrid(){
     grid = new HtmlPanelGrid();
     List<UIComponent> children = grid.getChildren();
     Collection<FieldFormatData> formats = dataManager.getFieldFormatData();
     for(FieldFormatData format:formats){
          HtmlOutputLabel outputLabel = new HtmlOutputLabel();
          outputLabel.setValue(format.getShortDesr());
          children.add(outputLabel);
          HtmlInputText inputText = new HtmlInputText();
          inputText.setSize(10);
          inputText.setMaxlength(10);
          System.out.println("Binding ................................... " + format.getEntityField());
          inputText.setValueBinding("value", FacesContext.getCurrentInstance().getApplication().createValueBinding("#{entity."+format.getEntityField()+"}"));
          children.add(inputText);
     return grid;

Exception Handling for Array Binding

Hi
1)
I am using a Stored Procedure.
I am using array binding and if i am sending an array of count 10 to be inserted in a table and only 9 got inserted,i deliberatly inserted one errorneous record in array, the count returned by ExecuteNonQuery() is 10.Why ?
How can i come to know exact number of rows inserted in table, how can i use Output variables, because the array bind count is 10 so if i add an output parameter it gives error ArrayBind count is wrong....
2)
Is it possible to roll back all the inserts if error occurs in any of the insert by Oracle engine.What it does is it inserts all correct records and leaves the errorneous record and doesn't even throw any exception or any message.
Answer - This can be achieved by using OracleTransaction and don't use Exception handling in procedure otherwise there wont be any exception thrown by procedure which is necessary to detect if an error occured during insert.If you use exception handling OracleEngine will insert correct rows and leave errorneous record and return count of inserted + non inserted records which is wrong.
Please help.
Message was edited by:
user556446
Message was edited by:
user556446

You'll need to encapsulate your validation within it's own block as described below:
-- this will die on the first exception
declare
TYPE T_BADDATA_TEST IS TABLE OF VARCHAR2(1000) INDEX BY binary_integer ;
tbt T_BADDATA_TEST ;
aBadTypeFound exception ;
begin
   tbt(0) := 'a';
   tbt(1) := 'b';
   tbt(2) := 'c';
    for idx in tbt.first..tbt.last loop
      if tbt(idx) = 'b' then
          raise aBadTypeFound ;
      else
          dbms_output.put_line(tbt(idx));
      end if ;
    end loop ;
end ;--encapsulate the exception area in a begin/end block to handle the exception but continue on
declare
TYPE T_BADDATA_TEST IS TABLE OF VARCHAR2(1000) INDEX BY binary_integer ;
tbt T_BADDATA_TEST ;
aBadTypeFound exception ;
begin
   tbt(0) := 'a';
   tbt(1) := 'b';
   tbt(2) := 'c';
    for idx in tbt.first..tbt.last loop
      BEGIN
      if tbt(idx) = 'b' then
          raise aBadTypeFound ;
      else
          dbms_output.put_line(tbt(idx));
      end if ;
      EXCEPTION
        WHEN aBadTypeFound THEN
            dbms_output.put_line(tbt(idx) || ' is bad data');
        WHEN OTHERS THEN
            dbms_output.put_line('exception');
      END ;
    end loop ;
end ;
output:
a
b is bad data
c
***/

Use field value in xml binding expression

Hi all.
I'm trying to access dropdownlist selected value from a binding expression.
I have a dropdownlist called rooms which is bound to some XML data. When the selection changes I woud like to access that value in another dropdownlist called members which is also bound to some XML data.
The expression I tried is:
$record.room.[roomname==$form.company.mainform.rooms.rawValue].member[*]
I'm calling this code on the rooms.changed event (alsop tried on rooms.exit event):
members.execCalculate();
Aparently $form.company.mainform.rooms.rawValue doesn't return the selected value of the rooms dropdownlist.
Is there a way to get the selected event from a different form and re-calculate binding of the field?
thanx

Binding is not dynamic ...meaning that it is set when the form is rendered and cannot be changed on the fly.
Paul

PL/SQL 101 : Exception Handling

Frequently I see questions and issues around the use of Exception/Error Handling in PL/SQL. More often than not the issue comes from the questioners misunderstanding about how PL/SQL is constructed and executed, so I thought I'd write a small article covering the key concepts to give a clear picture of how it all hangs together. (Note: the examples are just showing examples of the exception handling structure, and should not be taken as truly valid code for ways of handling things)
Exception Handling
Contents
1. Understanding Execution Blocks (part 1)
2. Execution of the Execution Block
3. Exceptions
4. Understanding Execution Blocks (part 2)
5. How to continue exection of statements after an exception
6. User defined exceptions
7. Line number of exception
8. Exceptions within code within the exception block
1. Understanding Execution Blocks (part 1)
The first thing that one needs to understand is almost taking us back to the basics of PL/SQL... how a PL/SQL execution block is constructed.
Essentially an execution block is made of 3 sections...
+---------------------------+
|    Declaration Section    |
+---------------------------+
|    Statements Section    |
+---------------------------+
|     Exception Section     |
+---------------------------+
The Declaration section is the part defined between the PROCEDURE/FUNCTION header or the DECLARE keyword (for anonymous blocks) and the BEGIN keyword. (Optional section)
The Statements section is where your code goes and lies between the BEGIN keyword and the EXCEPTION keyword (or END keyword if there is no EXCEPTION section). (Mandatory section)
The Exception section is where any exception handling goes and lies between the EXCEPTION keyword at the END keyword. (Optional section)
Example of an anonymous block...
DECLARE
.. declarative statements go here ..
BEGIN
.. code statements go here ..
EXCEPTION
.. exception handlers go here ..
END;
Example of a procedure/function block...
[CREATE OR REPLACE] (PROCEDURE|FUNCTION) <proc or fn name> [(<parameters>)] [RETURN <datatype>] (IS|AS)
.. declarative statements go here ..
BEGIN
.. code statements go here ..
EXCEPTION
.. exception handlers go here ..
END;
(Note: The same can also be done for packages, but let's keep it simple)
2. Execution of the Execution Block
This may seem a simple concept, but it's surprising how many people have issues showing they haven't grasped it. When an Execution block is entered, the declaration section is processed, creating a scope of variables, types , cursors, etc. to be visible to the execution block and then execution enters into the Statements section. Each statment in the statements section is executed in turn and when the execution completes the last statment the execution block is exited back to whatever called it.
3. Exceptions
Exceptions generally happen during the execution of statements in the Statements section. When an exception happens the execution of statements jumps immediately into the exception section. In this section we can specify what exceptions we wish to 'capture' or 'trap' and do one of the two following things...
(Note: The exception section still has access to all the declared items in the declaration section)
3.i) Handle the exception
We do this when we recognise what the exception is (most likely it's something we expect to happen) and we have a means of dealing with it so that our application can continue on.
Example...
(without the exception handler the exception is passed back to the calling code, in this case SQL*Plus)
SQL> ed
Wrote file afiedt.buf
1 declare
2    v_name VARCHAR2(20);
3 begin
4    select ename
5    into   v_name
6    from   emp
7    where empno = &empno;
8    dbms_output.put_line(v_name);
9* end;
SQL> /
Enter value for empno: 123
old   7:   where empno = &empno;
new   7:   where empno = 123;
declare
ERROR at line 1:
ORA-01403: no data found
ORA-06512: at line 4
(with an exception handler, we capture the exception, handle it how we want to, and the calling code is happy that there is no error for it to report)
SQL> ed
Wrote file afiedt.buf
1 declare
2    v_name VARCHAR2(20);
3 begin
4    select ename
5    into   v_name
6    from   emp
7    where empno = &empno;
8    dbms_output.put_line(v_name);
9 exception
10    when no_data_found then
11      dbms_output.put_line('There is no employee with this employee number.');
12* end;
SQL> /
Enter value for empno: 123
old   7:   where empno = &empno;
new   7:   where empno = 123;
There is no employee with this employee number.
PL/SQL procedure successfully completed.
3.ii) Raise the exception
We do this when:-
a) we recognise the exception, handle it but still want to let the calling code know that it happened
b) we recognise the exception, wish to log it happened and then let the calling code deal with it
c) we don't recognise the exception and we want the calling code to deal with it
Example of b)
SQL> ed
Wrote file afiedt.buf
1 declare
2    v_name VARCHAR2(20);
3    v_empno NUMBER := &empno;
4 begin
5    select ename
6    into   v_name
7    from   emp
8    where empno = v_empno;
9    dbms_output.put_line(v_name);
10 EXCEPTION
11    WHEN no_data_found THEN
12      INSERT INTO sql_errors (txt)
13      VALUES ('Search for '||v_empno||' failed.');
14      COMMIT;
15      RAISE;
16* end;
SQL> /
Enter value for empno: 123
old   3:   v_empno NUMBER := &empno;
new   3:   v_empno NUMBER := 123;
declare
ERROR at line 1:
ORA-01403: no data found
ORA-06512: at line 15
SQL> select * from sql_errors;
TXT
Search for 123 failed.
SQL>
Example of c)
SQL> ed
Wrote file afiedt.buf
1 declare
2    v_name VARCHAR2(20);
3    v_empno NUMBER := &empno;
4 begin
5    select ename
6    into   v_name
7    from   emp
8    where empno = v_empno;
9    dbms_output.put_line(v_name);
10 EXCEPTION
11    WHEN no_data_found THEN
12      INSERT INTO sql_errors (txt)
13      VALUES ('Search for '||v_empno||' failed.');
14      COMMIT;
15      RAISE;
16    WHEN others THEN
17      RAISE;
18* end;
SQL> /
Enter value for empno: 'ABC'
old   3:   v_empno NUMBER := &empno;
new   3:   v_empno NUMBER := 'ABC';
declare
ERROR at line 1:
ORA-06502: PL/SQL: numeric or value error: character to number conversion error
ORA-06512: at line 3
SQL> select * from sql_errors;
TXT
Search for 123 failed.
SQL>
As you can see from the sql_errors log table, no log was written so the WHEN others exception was the exception that raised the error to the calling code (SQL*Plus)
4. Understanding Execution Blocks (part 2)
Ok, so now we understand the very basics of an execution block and what happens when an exception happens. Let's take it a step further...
Execution blocks are not just a single simple block in most cases. Often, during our statements section we have a need to call some reusable code and we do that by calling a procedure or function. Effectively this nests the procedure or function's code as another execution block within the current statement section so, in terms of execution, we end up with something like...
+---------------------------------+
|    Declaration Section          |
+---------------------------------+
|    Statements Section          |
|            .                    |
| +---------------------------+ |
| |    Declaration Section    | |
| +---------------------------+ |
| |    Statements Section    | |
| +---------------------------+ |
| |     Exception Section     | |
| +---------------------------+ |
|            .                    |
+---------------------------------+
|     Exception Section           |
+---------------------------------+
Example... (Note: log_trace just writes some text to a table for tracing)
SQL> create or replace procedure a as
2    v_dummy NUMBER := log_trace('Procedure A''s Declaration Section');
3 begin
4    v_dummy := log_trace('Procedure A''s Statement Section');
5    v_dummy := 1/0; -- cause an exception
6 exception
7    when others then
8      v_dummy := log_trace('Procedure A''s Exception Section');
9      raise;
10 end;
11 /
Procedure created.
SQL> create or replace procedure b as
2    v_dummy NUMBER := log_trace('Procedure B''s Declaration Section');
3 begin
4    v_dummy := log_trace('Procedure B''s Statement Section');
5    a; -- HERE the execution passes to the declare/statement/exception sections of A
6 exception
7    when others then
8      v_dummy := log_trace('Procedure B''s Exception Section');
9      raise;
10 end;
11 /
Procedure created.
SQL> exec b;
BEGIN b; END;
ERROR at line 1:
ORA-01476: divisor is equal to zero
ORA-06512: at "SCOTT.B", line 9
ORA-06512: at line 1
SQL> select * from code_trace;
TXT
Procedure B's Declaration Section
Procedure B's Statement Section
Procedure A's Declaration Section
Procedure A's Statement Section
Procedure A's Exception Section
Procedure B's Exception Section
6 rows selected.
SQL>
Likewise, execution blocks can be nested deeper and deeper.
5. How to continue exection of statements after an exception
One of the common questions asked is how to return execution to the statement after the one that created the exception and continue on.
Well, firstly, you can only do this for statements you expect to raise an exception, such as when you want to check if there is no data found in a query.
If you consider what's been shown above you could put any statement you expect to cause an exception inside it's own procedure or function with it's own exception section to handle the exception without raising it back to the calling code. However, the nature of procedures and functions is really to provide a means of re-using code, so if it's a statement you only use once it seems a little silly to go creating individual procedures for these.
Instead, you nest execution blocks directly, to give the same result as shown in the diagram at the start of part 4 of this article.
SQL> ed
Wrote file afiedt.buf
1 create or replace procedure b (p_empno IN VARCHAR2) as
2    v_dummy NUMBER := log_trace('Procedure B''s Declaration Section');
3 begin
4    v_dummy := log_trace('Procedure B''s Statement Section');
5    -- Here we start another execution block nested in the first one...
6    declare
7      v_dummy NUMBER := log_trace('Nested Block Declaration Section');
8    begin
9      v_dummy := log_trace('Nested Block Statement Section');
10      select empno
11        into   v_dummy
12        from   emp
13       where empno = p_empno; -- Note: the parameters and variables from
                                     parent execution block are available to use!
14    exception
15      when no_data_found then
16        -- This is an exception we can handle so we don't raise it
17        v_dummy := log_trace('No employee was found');
18        v_dummy := log_trace('Nested Block Exception Section - Exception Handled');
19      when others then
20        -- Other exceptions we can't handle so we raise them
21        v_dummy := log_trace('Nested Block Exception Section - Exception Raised');
22        raise;
23    end;
24    -- ...Here endeth the nested execution block
25    -- As the nested block handled it's exception we come back to here...
26    v_dummy := log_trace('Procedure B''s Statement Section Continued');
27 exception
28    when others then
29      -- We'll only get to here if an unhandled exception was raised
30      -- either in the nested block or in procedure b's statement section
31      v_dummy := log_trace('Procedure B''s Exception Section');
32      raise;
33* end;
SQL> /
Procedure created.
SQL> exec b(123);
PL/SQL procedure successfully completed.
SQL> select * from code_trace;
TXT
Procedure B's Declaration Section
Procedure B's Statement Section
Nested Block Declaration Section
Nested Block Statement Section
No employee was found
Nested Block Exception Section - Exception Handled
Procedure B's Statement Section Continued
7 rows selected.
SQL> truncate table code_trace;
Table truncated.
SQL> exec b('ABC');
BEGIN b('ABC'); END;
ERROR at line 1:
ORA-01722: invalid number
ORA-06512: at "SCOTT.B", line 32
ORA-06512: at line 1
SQL> select * from code_trace;
TXT
Procedure B's Declaration Section
Procedure B's Statement Section
Nested Block Declaration Section
Nested Block Statement Section
Nested Block Exception Section - Exception Raised
Procedure B's Exception Section
6 rows selected.
SQL>
You can see from this that, very simply, the code that we expected may have an exception was able to either handle the exception and return to the outer execution block to continue execution, or if an unexpected exception occurred then it was able to be raised up to the outer exception section.
6. User defined exceptions
There are three sorts of 'User Defined' exceptions. There are logical situations (e.g. business logic) where, for example, certain criteria are not met to complete a task, and there are existing Oracle errors that you wish to give a name to in order to capture them in the exception section. The third is raising your own exception messages with our own exception numbers. Let's look at the first one...
Let's say I have tables which detail stock availablility and reorder levels...
SQL> select * from reorder_level;
   ITEM_ID STOCK_LEVEL
         1          20
         2          20
         3          10
         4           2
         5           2
SQL> select * from stock;
   ITEM_ID ITEM_DESC STOCK_LEVEL
         1 Pencils             10
         2 Pens                 2
         3 Notepads            25
         4 Stapler              5
         5 Hole Punch           3
SQL>
Now, our Business has told the administrative clerk to check stock levels and re-order anything that is below the re-order level, but not to hold stock of more than 4 times the re-order level for any particular item. As an IT department we've been asked to put together an application that will automatically produce the re-order documents upon the clerks request and, because our company is so tight-ar*ed about money, they don't want to waste any paper with incorrect printouts so we have to ensure the clerk can't order things they shouldn't.
SQL> ed
Wrote file afiedt.buf
1 create or replace procedure re_order(p_item_id NUMBER, p_quantity NUMBER) is
2    cursor cur_stock_reorder is
3      select s.stock_level
4            ,r.stock_level as reorder_level
5            ,(r.stock_level*4) as reorder_limit
6      from stock s join reorder_level r on (s.item_id = r.item_id)
7      where s.item_id = p_item_id;
8    --
9    v_stock cur_stock_reorder%ROWTYPE;
10 begin
11    OPEN cur_stock_reorder;
12    FETCH cur_stock_reorder INTO v_stock;
13    IF cur_stock_reorder%NOTFOUND THEN
14      RAISE no_data_found;
15    END IF;
16    CLOSE cur_stock_reorder;
17    --
18    IF v_stock.stock_level >= v_stock.reorder_level THEN
19      -- Stock is not low enough to warrant an order
20      DBMS_OUTPUT.PUT_LINE('Stock has not reached re-order level yet!');
21    ELSE
22      IF v_stock.stock_level + p_quantity > v_stock.reorder_limit THEN
23        -- Required amount is over-ordering
24        DBMS_OUTPUT.PUT_LINE('Quantity specified is too much. Max for this item: '
                                 ||to_char(v_stock.reorder_limit-v_stock.stock_level));
25      ELSE
26        DBMS_OUTPUT.PUT_LINE('Order OK. Printing Order...');
27        -- Here goes our code to print the order
28      END IF;
29    END IF;
30    --
31 exception
32    WHEN no_data_found THEN
33      CLOSE cur_stock_reorder;
34      DBMS_OUTPUT.PUT_LINE('Invalid Item ID.');
35* end;
SQL> /
Procedure created.
SQL> exec re_order(10,100);
Invalid Item ID.
PL/SQL procedure successfully completed.
SQL> exec re_order(3,40);
Stock has not reached re-order level yet!
PL/SQL procedure successfully completed.
SQL> exec re_order(1,100);
Quantity specified is too much. Max for this item: 70
PL/SQL procedure successfully completed.
SQL> exec re_order(2,50);
Order OK. Printing Order...
PL/SQL procedure successfully completed.
SQL>
Ok, so that code works, but it's a bit messy with all those nested IF statements. Is there a cleaner way perhaps? Wouldn't it be nice if we could set up our own exceptions...
SQL> ed
Wrote file afiedt.buf
1 create or replace procedure re_order(p_item_id NUMBER, p_quantity NUMBER) is
2    cursor cur_stock_reorder is
3      select s.stock_level
4            ,r.stock_level as reorder_level
5            ,(r.stock_level*4) as reorder_limit
6      from stock s join reorder_level r on (s.item_id = r.item_id)
7      where s.item_id = p_item_id;
8    --
9    v_stock cur_stock_reorder%ROWTYPE;
10    --
11    -- Let's declare our own exceptions for business logic...
12    exc_not_warranted EXCEPTION;
13    exc_too_much      EXCEPTION;
14 begin
15    OPEN cur_stock_reorder;
16    FETCH cur_stock_reorder INTO v_stock;
17    IF cur_stock_reorder%NOTFOUND THEN
18      RAISE no_data_found;
19    END IF;
20    CLOSE cur_stock_reorder;
21    --
22    IF v_stock.stock_level >= v_stock.reorder_level THEN
23      -- Stock is not low enough to warrant an order
24      RAISE exc_not_warranted;
25    END IF;
26    --
27    IF v_stock.stock_level + p_quantity > v_stock.reorder_limit THEN
28      -- Required amount is over-ordering
29      RAISE exc_too_much;
30    END IF;
31    --
32    DBMS_OUTPUT.PUT_LINE('Order OK. Printing Order...');
33    -- Here goes our code to print the order
34    --
35 exception
36    WHEN no_data_found THEN
37      CLOSE cur_stock_reorder;
38      DBMS_OUTPUT.PUT_LINE('Invalid Item ID.');
39    WHEN exc_not_warranted THEN
40      DBMS_OUTPUT.PUT_LINE('Stock has not reached re-order level yet!');
41    WHEN exc_too_much THEN
42      DBMS_OUTPUT.PUT_LINE('Quantity specified is too much. Max for this item: '
                              ||to_char(v_stock.reorder_limit-v_stock.stock_level));
43* end;
SQL> /
Procedure created.
SQL> exec re_order(10,100);
Invalid Item ID.
PL/SQL procedure successfully completed.
SQL> exec re_order(3,40);
Stock has not reached re-order level yet!
PL/SQL procedure successfully completed.
SQL> exec re_order(1,100);
Quantity specified is too much. Max for this item: 70
PL/SQL procedure successfully completed.
SQL> exec re_order(2,50);
Order OK. Printing Order...
PL/SQL procedure successfully completed.
SQL>
That's better. And now we don't have to use all those nested IF statements and worry about it accidently getting to code that will print the order out as, once one of our user defined exceptions is raised, execution goes from the Statements section into the Exception section and all handling of errors is done in one place.
Now for the second sort of user defined exception...
A new requirement has come in from the Finance department who want to have details shown on the order that show a re-order 'indicator' based on the formula ((maximum allowed stock - current stock)/re-order quantity), so this needs calculating and passing to the report...
SQL> ed
Wrote file afiedt.buf
1 create or replace procedure re_order(p_item_id NUMBER, p_quantity NUMBER) is
2    cursor cur_stock_reorder is
3      select s.stock_level
4            ,r.stock_level as reorder_level
5            ,(r.stock_level*4) as reorder_limit
6            ,(((r.stock_level*4)-s.stock_level)/p_quantity) as finance_factor
7      from stock s join reorder_level r on (s.item_id = r.item_id)
8      where s.item_id = p_item_id;
9    --
10    v_stock cur_stock_reorder%ROWTYPE;
11    --
12    -- Let's declare our own exceptions for business logic...
13    exc_not_warranted EXCEPTION;
14    exc_too_much      EXCEPTION;
15 begin
16    OPEN cur_stock_reorder;
17    FETCH cur_stock_reorder INTO v_stock;
18    IF cur_stock_reorder%NOTFOUND THEN
19      RAISE no_data_found;
20    END IF;
21    CLOSE cur_stock_reorder;
22    --
23    IF v_stock.stock_level >= v_stock.reorder_level THEN
24      -- Stock is not low enough to warrant an order
25      RAISE exc_not_warranted;
26    END IF;
27    --
28    IF v_stock.stock_level + p_quantity > v_stock.reorder_limit THEN
29      -- Required amount is over-ordering
30      RAISE exc_too_much;
31    END IF;
32    --
33    DBMS_OUTPUT.PUT_LINE('Order OK. Printing Order...');
34    -- Here goes our code to print the order, passing the finance_factor
35    --
36 exception
37    WHEN no_data_found THEN
38      CLOSE cur_stock_reorder;
39      DBMS_OUTPUT.PUT_LINE('Invalid Item ID.');
40    WHEN exc_not_warranted THEN
41      DBMS_OUTPUT.PUT_LINE('Stock has not reached re-order level yet!');
42    WHEN exc_too_much THEN
43      DBMS_OUTPUT.PUT_LINE('Quantity specified is too much. Max for this item: '
                              ||to_char(v_stock.reorder_limit-v_stock.stock_level));
44* end;
SQL> /
Procedure created.
SQL> exec re_order(2,40);
Order OK. Printing Order...
PL/SQL procedure successfully completed.
SQL> exec re_order(2,0);
BEGIN re_order(2,0); END;
ERROR at line 1:
ORA-01476: divisor is equal to zero
ORA-06512: at "SCOTT.RE_ORDER", line 17
ORA-06512: at line 1
SQL>
Hmm, there's a problem if the person specifies a re-order quantity of zero. It raises an unhandled exception.
Well, we could put a condition/check into our code to make sure the parameter is not zero, but again we would be wrapping our code in an IF statement and not dealing with the exception in the exception handler.
We could do as we did before and just include a simple IF statement to check the value and raise our own user defined exception but, in this instance the error is standard Oracle error (ORA-01476) so we should be able to capture it inside the exception handler anyway... however...
EXCEPTION
WHEN ORA-01476 THEN
... is not valid. What we need is to give this Oracle error a name.
This is done by declaring a user defined exception as we did before and then associating that name with the error number using the PRAGMA EXCEPTION_INIT statement in the declaration section.
SQL> ed
Wrote file afiedt.buf
1 create or replace procedure re_order(p_item_id NUMBER, p_quantity NUMBER) is
2    cursor cur_stock_reorder is
3      select s.stock_level
4            ,r.stock_level as reorder_level
5            ,(r.stock_level*4) as reorder_limit
6            ,(((r.stock_level*4)-s.stock_level)/p_quantity) as finance_factor
7      from stock s join reorder_level r on (s.item_id = r.item_id)
8      where s.item_id = p_item_id;
9    --
10    v_stock cur_stock_reorder%ROWTYPE;
11    --
12    -- Let's declare our own exceptions for business logic...
13    exc_not_warranted EXCEPTION;
14    exc_too_much      EXCEPTION;
15    --
16    exc_zero_quantity EXCEPTION;
17    PRAGMA EXCEPTION_INIT(exc_zero_quantity, -1476);
18 begin
19    OPEN cur_stock_reorder;
20    FETCH cur_stock_reorder INTO v_stock;
21    IF cur_stock_reorder%NOTFOUND THEN
22      RAISE no_data_found;
23    END IF;
24    CLOSE cur_stock_reorder;
25    --
26    IF v_stock.stock_level >= v_stock.reorder_level THEN
27      -- Stock is not low enough to warrant an order
28      RAISE exc_not_warranted;
29    END IF;
30    --
31    IF v_stock.stock_level + p_quantity > v_stock.reorder_limit THEN
32      -- Required amount is over-ordering
33      RAISE exc_too_much;
34    END IF;
35    --
36    DBMS_OUTPUT.PUT_LINE('Order OK. Printing Order...');
37    -- Here goes our code to print the order, passing the finance_factor
38    --
39 exception
40    WHEN exc_zero_quantity THEN
41      DBMS_OUTPUT.PUT_LINE('Quantity of 0 (zero) is invalid.');
42    WHEN no_data_found THEN
43      CLOSE cur_stock_reorder;
44      DBMS_OUTPUT.PUT_LINE('Invalid Item ID.');
45    WHEN exc_not_warranted THEN
46      DBMS_OUTPUT.PUT_LINE('Stock has not reached re-order level yet!');
47    WHEN exc_too_much THEN
48      DBMS_OUTPUT.PUT_LINE('Quantity specified is too much. Max for this item: '
                              ||to_char(v_stock.reorder_limit-v_stock.stock_level));
49* end;
SQL> /
Procedure created.
SQL> exec re_order(2,0);
Quantity of 0 (zero) is invalid.
PL/SQL procedure successfully completed.
SQL>
Lastly, let's look at raising our own exceptions with our own exception numbers...
SQL> ed
Wrote file afiedt.buf
1 create or replace procedure re_order(p_item_id NUMBER, p_quantity NUMBER) is
2    cursor cur_stock_reorder is
3      select s.stock_level
4            ,r.stock_level as reorder_level
5            ,(r.stock_level*4) as reorder_limit
6            ,(((r.stock_level*4)-s.stock_level)/p_quantity) as finance_factor
7      from stock s join reorder_level r on (s.item_id = r.item_id)
8      where s.item_id = p_item_id;
9    --
10    v_stock cur_stock_reorder%ROWTYPE;
11    --
12    exc_zero_quantity EXCEPTION;
13    PRAGMA EXCEPTION_INIT(exc_zero_quantity, -1476);
14 begin
15    OPEN cur_stock_reorder;
16    FETCH cur_stock_reorder INTO v_stock;
17    IF cur_stock_reorder%NOTFOUND THEN
18      RAISE no_data_found;
19    END IF;
20    CLOSE cur_stock_reorder;
21    --
22    IF v_stock.stock_level >= v_stock.reorder_level THEN
23      -- Stock is not low enough to warrant an order
24      [b]RAISE_APPLICATION_ERROR(-20000, 'Stock has not reached re-order level yet!');[/b]
25    END IF;
26    --
27    IF v_stock.stock_level + p_quantity > v_stock.reorder_limit THEN
28      -- Required amount is over-ordering
29

its nice article, have put up this one the blog
site,Nah, I don't have time to blog, but if one of the other Ace's/Experts wants to copy it to a blog with reference back to here (and all due credit given ;)) then that's fine by me.
I'd go for a book like "Selected articles by OTN members" or something. Does anybody have a list of links of all those mentioned articles?Just these ones I've bookmarked...
Introduction to regular expressions ... by CD
When your query takes too long ... by Rob van Wijk
How to pipeline a function with a dynamic number of columns? by ascheffer
PL/SQL 101 : Exception Handling by BluShadow

Default value for variable are not within permitted value range (precalc)

Hello BW community
Issue:
I have created a variable (Characteristic Value/ Manual input-default value) and use the precalculated value set (details-basic settings). In the further variable definition I could select the precalculated value set in 'Default values', which I have defined beforehand in the broadcaster..
The precalculated value set in the broadcaster settings is just based on a master data query on 0CUSTOMER.
Error:
The variable gets the error E991/R9E Errors: Default values for variable 'XXX' are not within permitted value range.
The detail description of the error is: You defined default values for variable 'Sold-to party precalc value set for manuel input' that are not appropriate for the variable type; for example, a range is defined as a default value for a variable that only permits a single value.
So please has someone had the same issue and found out how to solve it? It would be excelent to get good solution for this issue.
Best regards and thanks
Christian
PS-1: System BW 701 / SAPKW70105
PS-2 : there has been a SDN entry with the same topic but not resolved too.
link: /thread/980839 [original link is broken]

Hello,
Thanks for your response.
I should have mentioned that in my post. I tried this very first time. I thought that this is the place where you provide default value. But I got following exception at that time, so I thought, may be this is used for something else.
<LifecycleImpl> <_handleException> ADF_FACES-60098:Faces lifecycle receives unhandled exceptions in phase RENDER_RESPONSE 6
javax.faces.FacesException: javax.servlet.ServletException: OracleJSP error:
oracle.jbo.NameClashException: JBO-25001: Object viewAllInd of type Control Binding Definition already exists.
at com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:415)Do I need handle something else when you put the default value?
Thanks,
Jai

Exception Handling in bounded taskflows - expected behaviour

Hi,
I'm currently reviewing exception handling in bounded task flows and some things does not seems to be very clear for me.
(q1) Does it make sense that a bounded task flow calls a method (via a method activity) defined on the page definition of another page (outside of the BTF) by using a #{data.xxxmyPageDef.myMethodName.execute} EL expression?
(q2) Is is correct to expect the application to execute the method marked as ExceptionHandler in the taskflow, whenever an exception occurs?
(q3) I created 5 different scenarios where I call a service method which throws an exception, from within a page fragment of the BTF.
(q3 – sc1) Call a service method through the binding layer of the current page (by using #{bindings.xxx.execute})
Result: A dialog containing the exception message appears.
This is what I expected. Althought, the exception handler method does not seems to be invoked.(q3 – sc2) Call a service method through a task flow method activity using #{bindings.xxx.execute}
Result: A dialog containing the exception message appears.
This is what I expected. Althought, the exception handler method does not seems to be invoked.(q3 – sc3) Call a service method through a task flow method activity using #{data.myPageFragementPagedef.xxx.execute} (accessing the pageDef of the page fragment)
Result: Nothing happens.
This is not what I expected. Although, the exception handler method does nog seems to be invoked, I expect the ADF Error Handler to create a FacesMessage.(q3 – sc4) Call a service method through a task flow method activity using #{data.myPageContainingThePageFragmentPageDef.xxx.execute} (accessing the page containing the BTF region)
Result: Nothing happens.
This is not what I expected. Although, the exception handler method does nog seems to be invoked, I expect the ADF Error Handler to create a FacesMessage. (q3 – sc5) Call a service method through a task flow method activity using #{data.aPageOutsideTheBTFPageDef.xxx.execute} (accessing a page outside the BTW)
Result: Nothing happens.
This is not what I expected. Although, the exception handler method does nog seems to be invoked, I expect the ADF Error Handler to create a FacesMessage. (q4) How can it be possible that – without an exception handler – exceptions occur when calling method activities, without the exceptions being translated to FacesMessages?
Thanks in advance,
Koen Verhulst
JDeveloper 11.1.1.4

Koen,
+(q1) Does it make sense that a bounded task flow calls a method (via a method activity) defined on the page definition of another page (outside of the BTF) by using a #{data.xxxmyPageDef.myMethodName.execute} EL expression?+
No. Exceptions should be handled locally.
+(q2) Is is correct to expect the application to execute the method marked as ExceptionHandler in the taskflow, whenever an exception occurs?+
Only for exceptions that are before Render Response. The Render Response Phase is not handled in ADFc. So exceptions that occur in managed beans may fall through
+(q3) I created 5 different scenarios where I call a service method which throws an exception, from within a page fragment of the BTF.+
+(q3 – sc1) Call a service method through the binding layer of the current page (by using #{bindings.xxx.execute}) Result: A dialog containing the exception message appears.+
This is what I expected. Althought, the exception handler method does not seems to be invoked.
The binding layer has an error handler you can override in the DataBinings.cpx file
+(q3 – sc2) Call a service method through a task flow method activity using #{bindings.xxx.execute}+
Result: A dialog containing the exception message appears.
This is what I expected. Althought, the exception handler method does not seems to be invoked.
Again, you use the binding layer to invoke the service
+(q3 – sc3) Call a service method through a task flow method activity using #{data.myPageFragementPagedef.xxx.execute} (accessing the pageDef of the page fragment)+
Result: Nothing happens.
This is not what I expected. Although, the exception handler method does nog seems to be invoked, I expect the ADF Error Handler to create a FacesMessage.
Never use such a call. Its bad practice as there is no guarantee the container you reference is active. Always have the method call activity have its own binding defined when accessing a method call activity. I know there are lots of example floating aroundthat you #{data ...} and many are from 10.1.3. This should be avoided alltogether though
+(q3 – sc4) Call a service method through a task flow method activity using #{data.myPageContainingThePageFragmentPageDef.xxx.execute} (accessing the page containing the BTF region)+
Result: Nothing happens.
This is not what I expected. Although, the exception handler method does not seems to be invoked, I expect the ADF Error Handler to create a FacesMessage.
Again, this is not a proper use of the ADF framework.
+(q3 – sc5) Call a service method through a task flow method activity using #{data.aPageOutsideTheBTFPageDef.xxx.execute} (accessing a page outside the BTW)+
Result: Nothing happens. This is not what I expected. Although, the exception handler method does nog seems to be invoked, I expect the ADF Error Handler to create a FacesMessage.
accessing a page outside the BTW (!!!) This should ring a worst practices alarm on your laptop (obviously doesn't do it either)
+(q4) How can it be possible that – without an exception handler – exceptions occur when calling method activities, without the exceptions being translated to FacesMessages?+
Exceptions are not handled in a single place but stacked. The business service raises an exception and passes it to the binding layer if not handled. The binding layer handles the exception and if it can't passes it to ADFc. ADFc can handle this exception if it is not during Render Response.
Bottom line: There is no single point of exception handling. So as a recommendation for best practices
- Catch and handle exceptions as close as possible to their origins
- If things can go wrong, thy will - use try/catch blocks in managed beans
- Use an exception handling activity in all bounded task flows. In the case of task flow call activities being used exceptions can bubble up to the caller. However, this would take users out of their current application context
- Exceptions not handled in ADFc can be intercepted by overriding the application task flow exception handler (used by the exception handler activities). This would give you a chance e.g. to handle issues during Render Response
- Never fight the framework, never bend the framework: Don't use out of scope access to page definitions and resources. Exception handling is not a replacement for bad code practices (sorry for saying this, its not meant to be rude) :-)
Though I don't have a qualified numbers of bugs open for exception handling in ADF between 11.1.1.4 and now (and some that are open), but there are issues reported in this area. If there is something that really feels wrong, please go ahead and file a bug and provide a test case for development to have a look. The Render Response issue, for example is something we are aware of and that is in discussion (afaik knows, there is a change in exception handling in JSF 2 that may have an impact to what we can do in ADFc).
thanks
Frank

Bounded Taskflow Exception Handler not working with Page Fragements

I have one bounded - taskflow task-flow-definition
<?xml version="1.0" encoding="windows-1252" ?>
<adfc-config xmlns="http://xmlns.oracle.com/adf/controller" version="1.2">
<task-flow-definition id="task-flow-definition">
    <default-activity>view1</default-activity>
    <managed-bean>
      <managed-bean-name>backing_main</managed-bean-name>
      <managed-bean-class>view.backing.Main</managed-bean-class>
      <managed-bean-scope>pageFlow</managed-bean-scope>
    </managed-bean>
    <managed-bean>
      <managed-bean-name>backing_view1</managed-bean-name>
      <managed-bean-class>view.backing.View1</managed-bean-class>
      <managed-bean-scope>pageFlow</managed-bean-scope>
    </managed-bean>
    <managed-bean>
      <managed-bean-name>backing_view2</managed-bean-name>
      <managed-bean-class>view.backing.View2</managed-bean-class>
      <managed-bean-scope>pageFlow</managed-bean-scope>
    </managed-bean>
    <exception-handler>view2</exception-handler>
    <view id="view1">
      <page>/view1.jsff</page>
    </view>
    <view id="view2">
      <page>/view2.jsff</page>
    </view>
    <use-page-fragments/>
</task-flow-definition>
</adfc-config>view1.jsff contains one command button, which calls one ActionListener
<?xml version='1.0' encoding='windows-1252'?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="2.1"
          xmlns:af="http://xmlns.oracle.com/adf/faces/rich">
<af:commandButton text="commandButton 1" actionListener="#{pageFlowScope.backing_view1.callMyFunction}"
                    binding="#{pageFlowScope.backing_view1.commandButton1}"
                    id="commandButton1"/>

</jsp:root>view1.java callMyFunction throws an Exception
    public void callMyFunction(ActionEvent event) throws Exception{
        throw new Exception();
    }view2.jsff is an exception handler
<?xml version='1.0' encoding='windows-1252'?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="2.1"
          xmlns:af="http://xmlns.oracle.com/adf/faces/rich">
<af:activeOutputText value="Exception Occured"
                       binding="#{pageFlowScope.backing_view2.activeOutputText1}"
                       id="activeOutputText1"
                       inlineStyle="font-size:xx-large; color:red;"/>

</jsp:root>above taskflow is dragged-drop as a Region in one file main.jspx
<?xml version='1.0' encoding='windows-1252'?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="2.1"
          xmlns:f="http://java.sun.com/jsf/core"
          xmlns:h="http://java.sun.com/jsf/html"
          xmlns:af="http://xmlns.oracle.com/adf/faces/rich">
<jsp:directive.page contentType="text/html;charset=windows-1252"/>
<f:view>
    <af:document binding="#{pageFlowScope.backing_main.document1}"
                 id="document1">
      <af:form binding="#{pageFlowScope.backing_main.form1}" id="form1">
        <af:region value="#{bindings.taskflowdefinition1.regionModel}"
                   id="taskf1"
                   binding="#{pageFlowScope.backing_main.taskf1}"/>
      </af:form>
    </af:document>
</f:view>

</jsp:root>*pressing a commandButton on view1.jsff throws an Exception as expected but does not go to exceptionHandler [view2.jsff]*
However, this does work with Bounded Task-Flow without page fragments , view1.jspx contains one button, calling one method which throws an Exception,
view2.jspx is an Exception Handler, and in this case it redirects to the view2.jspx [error page]
any ideas?
thanks

Hi,
Pretty much. However, you got the event part wrong, which is mostly my fault here. First, let put down some general JSF facts about event handling.
1. http://java.sun.com/javaee/5/docs/api/javax/faces/component/UIComponent.html#queueEvent(javax.faces.event.FacesEvent)
2. So, basically, queuing an event on a component means queuing it on its parent until you reach the UIViewRoot that will really actually queue it. That strategy allows iterating components to intercept event queued on their children to record the row index as well so that the data model can be synchronized correctly during the broadcast phase (see http://java.sun.com/javaee/5/docs/api/javax/faces/component/UIData.html#queueEvent(javax.faces.event.FacesEvent) and http://java.sun.com/javaee/5/docs/api/javax/faces/component/UIData.html#broadcast(javax.faces.event.FacesEvent))
3. Exceptions that aren't handled by the exception handler are thrown during broadcast or various process* methods.
So, the catch component must leverage these facts to intercept events queued on its children (by overriding queueEvent method) wrapping the original event in a custom on that flag the catch component itself as the source of the event. The result will be that the broadcast method of the catch component will be called to handle the event. The broadcast method must then unwrap the event (to get the original event), gets the original source, then call originalSource.broadcast(originalEvent) within a try-catch block.
Does it make any more sense put that way? Note that it's an obscure part of JSF so I cannot make it incredibly simple either.
Regards,
~ Simon

Exception handling within a value-binding expression

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