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JSF Tip #7 - The RequiredValidator

Posted by mriem on September 7, 2012 at 8:33 PM PDT

Say you want to make sure that a value is required.

 <html xmlns:h="http://java.sun.com/jsf/html"  xmlns:f="http://java.sun.com/jsf/core">
  <h:inputText value="#{user.firstName}">
   <f:validateRequired/>
  </h:inputText>
</html>

If you want to disable the RequiredValidator on a page you can mark the validator as disabled as follows:

 <html xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core">
  <h:inputText value="#{user.firstName}">
   <f:validateRequired disabled="true" />
  </h:inputText>
</html>

If you keep an instance of a RequiredValidator around in your managed bean you can also use binding to bind that particular instance of the RequiredValidator to the tag on the page like so:

 <html xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core">
  <h:inputText value="#{user.firstName}">
   <f:validateRequired binding="#{settings.requiredValidator}" />
  </h:inputText>
</html>

And a managed bean that has a method similar to the one below:

 public RequiredValidator getRequiredValidator() {
  return requiredValidator;
}

If you specifically want to attach the validator to a specific component then you can use the 'for' attribute to target it. Note this attribute is really helpful when using composite components. Eg.

 <html xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core">
  <h:inputText id="myinput" value="#{donation.amount}">
   <f:validateRequired binding="#{settings.firstNameValidator}" for="myinput"/>
  </h:inputText>
</html>
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