JavaServer Faces 1.x does not explicitly support client-side validation and only provides a minimal set of server-side validators. On the other hand, Apache Commons Validator supports both client- and server-side validators and comes with the following useful validators:
Shale provides three JSP tags that let you use the Commons Validator:
s:commonsValidator,
s:validatorVar,
and s:validatorScript. The
first two lets you attach a commons validator to a JSF input component and
the third generates JavaScript validation code for validating each JSF component
that has one or more Commons validators in a particular form. You can attach as
many Commons validators to a single JSF input component as you wish.
Here's what you need to do to use Shale validation:
onsubmit attribute to your h:form tag that calls
the JavaScript validation function generated by s:validatorScript.
s:commonsValidator
and, optionally, s:validatorVar.
s:validatorScript tag at the end of the h:form tag's body.
<%@ taglib uri="http://shale.apache.org/core" prefix="s" %>
...
<h:form onsubmit="return validateForm(this);">
<h:inputText id="creditCardNumber"
size="16"
value="#{userContext.creditCardNumber}">
<s:commonsValidator type="required"
arg="#{msgs.creditCardNumberPrompt}"
server="true"
client="true"/>
<s:commonsValidator type="mask"
arg="#{msgs.creditCardNumberPrompt}"
server="true"
client="true">
<s:validatorVar name="mask" value="[4-6].*"/>
</s:commonsValidator>
<s:commonsValidator type="creditCard"
arg="#{msgs.creditCardNumberPrompt}"
server="true"/>
</h:inputText>
<h:message for="creditCardNumber" styleClass="errors"/>
<s:validatorScript functionName="validateForm"/>
</h:form>
...
In the preceding example, we've attached three Commons validators to a single JSF input component. To pass validation, the field must have a value that starts with a number between 4 and 6 inclusive and that value must be a valid credit card number as verified by the Luhn algorithm. Two of the validations are performed on both client and server and one is performed on the server only.
Note: At the present time, you have the option to forego server-side validation, which is considered very bad practice. Users can turn off JavaScript, so you should always backup client-side validation with server-side validation. In the future, Shale may enforce server-side validation if it's not explicitly specified.
Shale's Commons Validator integration also allows you to use custom validation rules.
In most cases, you will want to include the default rule set in
addition to your custom rules. In web.xml, use the
org.apache.shale.validator.VALIDATOR_RULES context
initialization parameter to specify a comma delimited list of files.
<!-- Shale Validator Configuration Resources -->
<context-param>
<param-name>org.apache.shale.validator.VALIDATOR_RULES</param-name>
<param-value>
/org/apache/shale/validator/validator-rules.xml,
/WEB-INF/custom-rules.xml
</param-value>
</context-param>
In this example, the default validator-rules.xml file will be loaded from the shale-core.jar archive, and the custom-rules.xml file will be loaded from WEB-INF.
To replace one of the provided rules, place a modified copy of validator-rules.xml in your webapp, and refer to it instead of the default file.
To add messages for your own validation rules, or to customize the provided messages, configure a message bundle for your application in /WEB-INF/faces-config.xml.
More information on Shale's Commons Validator integration, including step-by-step examples, can be found on the ShaleValidation Wiki page.