Customizing Stripes Messages - Stripes...and Java Web Development is Fun Again - page 126

6.4 Creating Messages for Custom Errors

Back on page 111 , we created a PhoneNumberTypeConverter class to con-
vert an input String to a PhoneNumber . If the input was not valid, we
created an error. The error message was directly in the code:

Download email_12/src/stripesbook/ext/PhoneNumberTypeConverter.java

errors.add( new SimpleError("{1} is not a valid {0}"));

With all other error messages in the StripesResources.properties file, it'd be
a shame not to have messages for custom errors in there as well. Say
we wanted to use the following key:

contact.phoneNumber.invalid

To use the message defined with this key, we can simply use the Local-
izableError class. This class allows us to specify a resource bundle key
instead of a hard-coded message. For example:

errors.add(
new LocalizableError("contact.phoneNumber.invalid");

Now we can define the error message in StripesResources.properties with
all the other error messages:

Download email_15/res/StripesResources.properties

contact.phoneNumber.invalid=The phone number is not valid.

That's fine when you are creating errors that are specific to our appli-
cation. But PhoneNumberTypeConverter is useful for any phone number
field, not just the one in the contact form. In fact, word of your phone
number type converter has spread around the office, and people from
other departments have asked us whether they could use it in their
applications.

The problem right now is that we're limited to the same error message
for every phone number field. What if other developers use PhoneNum-
berTypeConverter in more than one form and need different error mes-
sages in each form?

The ScopedLocalizableError class is specifically designed for use in type
converters such as PhoneNumberTypeConverter . It takes advantage of
the key lookup mechanism, just like the type converters provided by
Stripes.