Re: [Springframework-developer] Tags

[Ken K. <kk...@kk...>]

JP,

Petclinic shows an example of this on the add/edit Pet forms and the 
addVisit form. Look at the messages.properties for the typeMismatch 
messages.

I got a reply from Juergen when I queried about this situation (sent on 
17-JUN). See my original message and the reply below.

As to keeping the data intact, your FormController should set the 
sessionForm property to true. In petclinic, this is done in the 
constructor. The date editor is setup in AbstractClinicForm.initBinder().

There is a problem with this technique in that this process will retain 
the bad date data that was entered but not other subsequent data on the 
form as it seems to short circuit the rest of the binding process. Try 
entering something in the Description field on the addVisit form. Then 
enter a bad date, submit and see what happens. Perhaps I'm not doing it 
quite right ??

Initially, I tried to work around the ugly stacktrace message I was 
getting by creating my own date editor and trapping the ParseException 
and setting the field to null, thereby handing it off to the validator. 
Ideally, it would be nice if the custom editor would participate in the 
same way as validators do, IMO.

Regards,
Ken


jp....@ti... wrote:

>Hi,
>I have a basic problem with the form validation. Ok for rejectValue from a validator, but how to handle Mismatch errors from the binder itself? 
>Assume using a date field that is malformed by the user. The editor will not be able to parse the date. Currently I come back to the form page as expected. But:
>1) The malformed data is lost. The field is empty.
>2) The status.errorMessage is void also.
>
>How not loose the initial input and how be able to write an error message to the user?
>
>Sorry for a so basic question, but if I cannot find the solution, it will be worse for new users.
>
>Jean-Pierre
>
>
>  
>



Juergen's reply:

>  
>
Hi Ken,
 
You can easily replace the default error message by defining a 
MessageSource, i.e. a "messages.properties" bundle or the like. If you 
define a message for the key "typeMismatch" there, you'll see that 
message in your form in case of an error with code "typeMismatch". You 
can even define more specific messages like for "typeMismatch.myField" 
or even "typeMismatch.myObject.myField" that will only get used on the 
specified field resp. object and field. Of course this works with your 
own error codes that your own validator produces too. See the FieldError 
javadoc for details.
 
So I'd suggest to stick to CustomDateEditor but override the respective 
messages. This will both keep the offending entry and provide a 
localized message. Is that what you meant to achieve? If there's 
anything left, let's try to extend CustomDateEditor accordingly.
 
Juergen
 
 
-----Original Message-----
*From:* Ken Krebs [mailto:kk...@kk...]
*Sent:* Tuesday, June 17, 2003 7:32 PM
*To:* jürgen höller [werk3AT]
*Cc:* 'spring-dev-list'
*Subject:* MVC binding and validation

Juergen,

NOTE: This little problem is not pressing as I have an acceptable 
solution in place for petclinic which will be posted Real Soon Now  ;-) .

In a couple of my petclinic forms, I use BaseCommandController's 
initBinder method to install a custom Date PropertyEditor to handle 
dates of the form "yyyy-mm-dd". The framework class CustomDateEditor is 
not convenient to subclass so I used it's code as a basis for my own 
SimpleDateEditor (code is shown below). In this class's setAsText 
method, I handle the ParseException to set the object  to null because I 
do not like the error message that gets bound in if I let it throw an 
IllegalArgumentException as does CustomDateEditor. The message looks 
like a stack trace and would be incomprehensible to the average end 
user, i.e.: *Failed to convert property value of type [java.lang.String] 
to required type [java.util.Date]; nested exception is: 
java.lang.IllegalArgumentException: Could not parse date: Unparseable 
date: "2000-06-"*. This message comes from BeanWrapperImpl's 
setPropertyValue throwing a TypeMismatchException. Setting the object 
value to null allows the problem to be handled by my validator which 
simply reports the now erased date entry as "invalid". Obviously, this 
is not ideal. It would be better to allow the PropertyEditor to provide 
a user-friendly, localizable exception while preserving the offending 
entry. Unfortunately, setAsText can't throw  any checked Exceptions like 
the ErrorCodedPropertyVetoException that DataBinder's bind method uses.

What do you think ?



Ken


/*
 * SimpleDateEditor.java
 *
 */

package petclinic.validation;

import java.util.Date;
import java.beans.PropertyEditorSupport;
import java.text.SimpleDateFormat;
import java.text.ParseException;

/**
 *
 *  @author  Ken Krebs
 */
public class SimpleDateEditor extends PropertyEditorSupport {
   
    private SimpleDateFormat dateFormat;
   
    /** Creates a new instance of SimpleDateEditor */
    public SimpleDateEditor() {
        dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        dateFormat.setLenient(false);
    }
   
    /**
     *  Parse the Date from the given text, using the specified DateFormat.
     *  Trap a ParseException to allow the Validator to handle it.
     */
    public void setAsText(String text) {
        try {
            setValue(this.dateFormat.parse(text));
        } catch (ParseException ex) {
            //    throw new IllegalArgumentException("Could not parse 
date: " + ex.getMessage());
            setValue(null);
        }
    }
   
    /**
     * Format the Date as String, using the specified DateFormat.
     */
    public String getAsText() {
        return this.dateFormat.format((Date) getValue());
    }
   
}