Validating User Input - Stripes...and Java Web Development is Fun Again - page 71

Using ${ } in Expressions

Enclose the validation expression within ${ } , or don't—the
choice is yours. Indeed, expression="this < today" and expres-
sion="${this < today}" are equivalent. Stripes automatically adds
${ } for you if you leave it out.
Personally, I prefer using ${ } because I find it makes it clearer
that an EL expression is being used. Whichever format you
choose, being consistent will certainly make your code more
readable.

prefix and a four-digit suffix, as in [phone] . To be lenient with our
users, we'll allow some flexibility with the input format:

• The parentheses around the area code are optional.

• The separators between each part of the phone number can be
hyphens, periods, or spaces, or they can be omitted altogether.

For example, all these phone numbers are acceptable:

[phone] 654-456-4567 654 456 4567 654.456.4567

[phone] 6544564567 654 4564567 654.456-4567

Adding this validation is easy by building a regular expression mask
with the following constructs:

• \(? and \)? to represent an optional opening and closing paren-
thesis

• [-. ]? to accept an optional hyphen, period or space

• \d to represent a digit

• {N} to indicate the previous construct repeated N times

With these constructs, we can validate the phone number by adding
the following mask. Since the regular expression is in a Java String , we
have to use \\ to represent \ .

Download email_06/src/stripesbook/action/ContactFormActionBean.java
@ValidateNestedProperties({
/ * previous validations... * /
@Validate(field="phoneNumber",
mask="\\(?\\d{3}\\)?[-. ]?\\d{3}[-. ]?\\d{4}")

})