Validating User Input - Stripes...and Java Web Development is Fun Again - page 62

Attribute Type Description

Name of nested field to validate. field= String

true indicates a required field. required= boolean

on= String []

Event handlers for which to apply required=true .

Minimum length of input.

minlength= int

Maximum length of input. maxlength= int

EL expression to validate the input. expression= String

mask= String

Regular expression that the input must match.

Minimum numerical value of input

minvalue= double

Maximum numerical value of input. maxvalue= double

Type converter to use on the input. converter= Class

Trim input before validating; true by default. trim= boolean

Label to be displayed to the user.

label= String

true indicates not to bind the parameter. ignore= boolean

true encrypts the parameter to prevent injected values. encrypted= boolean

Figure 4.2: The @Validate attributes

• Validation with an EL expression
• Matching a regular expression mask
• Minimum and maximum numerical value

Other validations are implemented as “pseudo” type converters. Pseudo
because the type conversion is from String to String , so the type is not
really converted. But when any type conversion occurs, the input is
validated. Stripes uses this trick to validate two String input formats:

• Email addresses
• Credit card numbers

In Figure 4.2 , we can see the complete list of @Validate attributes. We'll
use most of these attributes in the examples of this chapter. We'll see
how to use the label= in Chapter 6 , Customizing Stripes Messages, on
page 121 . The ignore= and encrypted= attributes are discussed in Chap-
ter 14 , It's a Dangerous World: Adding Security, on page 307 .

Controlling Validation Execution
When a request arrives at an action bean, Stripes considers all valida-
tions you've added, no matter which event handler is the target. With
event handlers that require different validations, you'll want to control