DO NOT REPLY [Bug 27321] New: - Automatic invalid format handling for form bean

[bu...@apache.org]

DO NOT REPLY TO THIS EMAIL, BUT PLEASE POST YOUR BUG 
RELATED COMMENTS THROUGH THE WEB INTERFACE AVAILABLE AT
<http://nagoya.apache.org/bugzilla/show_bug.cgi?id=27321>.
ANY REPLY MADE TO THIS MESSAGE WILL NOT BE COLLECTED AND 
INSERTED IN THE BUG DATABASE.

http://nagoya.apache.org/bugzilla/show_bug.cgi?id=27321

Automatic invalid format handling for form bean

           Summary: Automatic invalid format handling for form bean
           Product: Struts
           Version: 1.1RC2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: Enhancement
          Priority: Other
         Component: Controller
        AssignedTo: struts-dev@jakarta.apache.org
        ReportedBy: enzhongfu@adelphia.net


Currently, Struts recommends all fields of ActionForm be of type String. If you 
use other type (such as Date), and user inputs the value in an invalid format 
so the value could not convert to the suitable type, BeanUtils would throw an 
exception and it would propagate back to the user. Use only String type for 
ActionForm fields can display to the user the original values they input, but 
in Action class code is needed to transform from String type to type used in 
business objects.

Not all people like this. Today one more developer posted it as a bug. Ideally, 
we hope to use more types in a form bean while still able to display the 
original inputs to the user when a validation error occurs. I think the 
following solution can achieve it,

0. Basic validation, "Valid Format" and "Required", should be handled before 
populating form bean.

1. In RequestProcessor class, processPopulate() should mimic processValidate(). 
It returns a boolean to indicate whether processPopulate is successful or not. 
If not successful, it should forward to the input page like processValidate 
does.

2. Instead of throwing exception, BeanUtils class should catch the exception 
for populating error and continue. It returns a list of the fields that have 
problem (normally invalid format). Error messages constructed based on these 
fields will be stored in Globals.ERROR_KEY.

3. When there is populating error, a HashMap is created to hold the original 
request parameters (all Strings, nested fields can have nested HashMaps). The 
HashMap is stored at a global key (Globals.xxx) in the request.

4. The html:form tag will get the stored HashMap and put it to 
Constants.BEAN_KEY for field tags to use (when there is populating error).

Thus, you can use other types in form bean (nest business objects in form bean, 
for example) and Struts can still display the user's original input when in 
error. I tried it on Struts1.1-rc2 and it worked. 

An alternative solution is that in RequestProcessor, process() can catch the 
exception and call processException(). It's up to the developer to provide 
handler to deal with the invalid format. They can implement this proposal there.

---------------------------------------------------------------------
To unsubscribe, e-mail: struts-dev-unsubscribe@jakarta.apache.org
For additional commands, e-mail: struts-dev-help@jakarta.apache.org