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From Blake Sullivan <blake.sulli...@oracle.com>
Subject Re: [Trinidad][API] New Exception tells whether JSF needs to report the exception for TRINIDAD-2038
Date Thu, 17 Feb 2011 00:45:22 GMT
The issue isn't that the problem has been handled by the model.  It 
hasn't.  Therefore the model has to throw a RuntimeException in this 
case so that the component knows to preserve its local value.  That's 
all good.

The problem occurs if the model has its own mechanisms for reporting 
problems.  In that case, we want to avoid reporting the same problem 
twice and that is where the interface comes in.  The model wants to tell 
the view that there was a problem, but that the model will take care of 
reporting it, so the view needn't bother.

-- Blake Sullivan

On 2/16/11 4:39 PM, Scott O'Bryan wrote:
> If this exception is handled, why is it rethrown?  What would you
> expect Trinidad to do in this case?
>
> On Feb 16, 2011, at 5:37 PM, Hongbing<hongbing.wang@oracle.com>  wrote:
>
>> Hi Scott:
>> One example is in the following UIXEditableValue.updateModel(FacesContext context)
code,
>>
>>   public void updateModel(FacesContext context)
>>   {
>>     ....
>>     try
>>     {
>>       Object localValue = getLocalValue();
>>       expression.setValue(context.getELContext(), localValue);
>>       setValue(null);
>>       setLocalValueSet(false);
>>       if (_LOG.isFiner())
>>       {
>>         _LOG.finer("Wrote value {0} to model {1} in component {2}",
>>                    new Object[]{localValue,
>>                                 expression.getExpressionString(),
>>                                 this});
>>       }
>>     }
>>     catch (RuntimeException e)
>>     {
>>     ...
>>
>>   expression.setValue(context.getELContext(), localValue) calls binding code and
then the model's code, where exception can be thrown.
>>   In the catch part, we want to skip reporting the exception if it is handled by
model/controller code.
>>
>>
>> Thanks,
>> Hongbing
>>
>>
>>
>> On 2/16/2011 4:23 PM, Scott O'Bryan wrote:
>>> Hogbing,
>>>
>>> I'm taking a look at the bug now but just so I understand..  When you
>>> refer to JSF, I assume you mean the Trinidad renderkit.  Is that
>>> correct?
>>>
>>> Scott
>>>
>>> On Feb 16, 2011, at 4:23 PM, Hongbing<hongbing.wang@oracle.com>   wrote:
>>>
>>>> Hi Pavitra:
>>>> It can happen in update model phase. For example, Model layer throws exception
when attribute value validation fails, binding layer detects it and re-throwd new exception
with the new interface to JSF. JSF then can handle it accordingly.
>>>>
>>>> thanks,
>>>> Hongbing
>>>>
>>>> On 2/16/2011 2:09 PM, Pavitra Subramaniam wrote:
>>>>> Hello Hongbing,
>>>>>
>>>>> You mentioned that exceptions get thrown by model layer outside of JSF.
Can you give an e.g., of when this might occur?
>>>>> How exactly will the interface get used?
>>>>>
>>>>> Thanks
>>>>> Pavitra
>>>>>
>>>>>
>>>>>
>>>>> On 2/16/2011 1:01 PM, Hongbing wrote:
>>>>>> Hi:
>>>>>> This is for JIRA TRINIDAD-2038, please let me know your suggestion.
>>>>>>
>>>>>> There are cases that exception is thrown in update model phase, like
model layer validation failure, by model outside of JSF and the exception is also handled
and reported outside of JSF. To avoid the component's local value getting reset to null, JSF
needs to be notified when it happens. The proposed solution is to re-throw a special exception
to JSF to notify it and also let JSF know whether it needs to report the exception.
>>>>>>
>>>>>> Here is the interface of the exception:
>>>>>> package org.apache.myfaces.trinidad.context;
>>>>>>
>>>>>> /**
>>>>>> * Interface for exceptions that tells whether the exception needs
to be reported.
>>>>>> * If an exception is thrown during JSF lifycycle and aleady reported,
then it should let
>>>>>> * JSF know not to report it again.
>>>>>> *
>>>>>> */
>>>>>> public interface Reportable
>>>>>> {
>>>>>>
>>>>>>   /**
>>>>>>    * Return false if JSF doesn't need to report this exception, otherwise
true.
>>>>>>    */
>>>>>>   public boolean isReportingMessage();
>>>>>>
>>>>>> }
>>>>>>
>>>>>> Thanks,
>>>>>> Hongbing
>>>>>>
>>>>>>


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