Re: [Springframework-developer] BindException changes

[Dmitriy K. <dko...@ru...>]

Ben,

you don't need to do anything special here. Simply provide a custom 
message in "messages.properties" found in the classpath for a 
"typeMismatch.{property_name} key and Spring will take care of the rest i.e.

typeMismatch.luhn=A valid Luhn is required

Also don't forget to configure the MessageSource bean in your app 
context with base name of "messages":

<!-- Message source for this context, loaded from localized 
"messages_xx" files -->
    <bean id="messageSource" 
class="org.springframework.context.support.ResourceBundleMessageSource">
        <property name="basename"><value>messages</value></property>    
                                   
    </bean>

Take a look at Petclinic's example.

Cheers,
Dmitriy.


Ben Alex wrote:

> I'm using SimpleFormController to process a form containing a 
> parameter that is converted to a Long value in the form backing 
> object. The Long has a check digit and thus there are both number 
> format exceptions as well as check digit related exceptions possible. 
> By default such errors will cause the following messages to be 
> displayed to the user in the errors list:
>
> Failed to convert property value of type [java.lang.String] to 
> required type [java.lang.Long] for property 'luhn'; nested exception 
> is java.lang.IllegalArgumentException: Cannot parse number: 
> Unparseable number: "aString"
>
> or
>
> Property 'luhn' threw exception; nested exception is 
> java.lang.IllegalArgumentException: Business key must be a valid Luhn 
> identifier
>
> Neither response is suitable for display to users. I would rather 
> replace these with my own more user-friendly message. One approach 
> discussed at http://forum.springframework.org/viewtopic.php?t=1098 
> (last post by ojolly) is for the PropertyEditor to set the object to 
> null, then detect something was actually entered in the request 
> parameter in onBindAndValidate and then add a friendly error. That's 
> OK, but then you lose whatever the user actually typed in as the 
> PropertyEditor set it to null. This is unacceptable as quite often the 
> data entered will be close to what it should have been (eg an unwanted 
> fractional portion for an integer, a mis-typed digit for a 
> checksum-based number, a property that is simply too long etc).
>
> I ended up writing a MyBindException which subclasses BindException 
> and provides these two methods:
>
>    public void removeError(ObjectError error) {
>        this.errors.remove(error);
>    }
>      public void removeErrors(List objectErrors) {
>        Iterator iter = objectErrors.iterator();
>        while (iter.hasNext()) {
>            ObjectError objectError = (ObjectError) iter.next();
>            removeError(objectError);
>        }
>    }
>
> My controller then does this:
>
>    protected void onBindAndValidate(HttpServletRequest request,
>            Object command, BindException errors) throws Exception {
>        Person person = (Person) command;
>        if (errors.hasFieldErrors("luhn")) {
>            // Cast is safe as createBinder caused MyBindException to 
> be used
>            MyBindException myErrors = (MyBindException) errors;
>            errors.rejectValue("luhn", "LUHN_INVALID", "A valid Luhn is 
> required.");
>        } ....
>
> This works great. It consumes the unwanted, uninformative user 
> feedback and replaces it. It also avoids needing to look at 
> HttpServetRequest parameters. The problem is to achieve this I've 
> needed to write MyBindException, copy nine methods to it (as the 
> errors List is private in the BindException superclass), write a 
> MyServletRequestDataBinder to set it up, and then override 
> createBinder in the controller to use MyServletRequestDataBinder. It 
> seems a lot of work, so I was hoping we could add the above two 
> methods to BindException? Alternatively, at least making the errors 
> List protected in BindException will save the ugly code duplication.
>
> Alternatively, if there's another way entirely of achieving this, I'd 
> be grateful if someone would let me know.
>
> Best regards
> Ben
>
>
>
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