[Springframework-developer] RE: MVC binding and validation

[<jue...@we...>]

Hi Ken,
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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.
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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.
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Juergen
=20
=20

-----Original Message-----
From: Ken Krebs [mailto:kk...@kk...]
Sent: Tuesday, June 17, 2003 7:32 PM
To: j=FCrgen h=F6ller [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 {
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    private SimpleDateFormat dateFormat;
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    /** Creates a new instance of SimpleDateEditor */
    public SimpleDateEditor() {
        dateFormat =3D new SimpleDateFormat("yyyy-MM-dd");
        dateFormat.setLenient(false);
    }
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    /**
     *  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);
        }
    }
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    /**
     * Format the Date as String, using the specified DateFormat.
     */
    public String getAsText() {
        return this.dateFormat.format((Date) getValue());
    }
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}