org.omnifaces.taghandler

Class ValidateBean

java.lang.Object

javax.faces.view.facelets.TagHandler

org.omnifaces.taghandler.ValidateBean

All Implemented Interfaces:

FaceletHandler

public class ValidateBean
extends TagHandler

The <o:validateBean> allows the developer to control bean validation on a per-UICommand or UIInput component basis, as well as validating a given bean at the class level.

The standard <f:validateBean> only allows validation control on a per-form or a per-request basis (by using multiple tags and conditional EL expressions in its attributes) which may end up in boilerplate code.

The standard <f:validateBean> also, despite its name, does not actually have any facilities to validate a bean at all.

Usage

Some examples

Control bean validation per component

 <h:commandButton value="submit" action="#{bean.submit}">
     <o:validateBean validationGroups="javax.validation.groups.Default,com.example.MyGroup" />
 </h:commandButton>
 

 <h:selectOneMenu value="#{bean.selectedItem}">
     <f:selectItems value="#{bean.availableItems}" />
     <o:validateBean disabled="true" />
     <f:ajax execute="@form" listener="#{bean.itemChanged}" render="@form" />
 </h:selectOneMenu>
 

Validate a bean at the class level

 <h:inputText value="#{bean.product.item}" />
 <h:inputText value="#{bean.product.order}" />

 <o:validateBean value="#{bean.product}" validationGroups="com.example.MyGroup" />
 

Class level validation details

In order to validate a bean at the class level, all values from input components should first be actually set on that bean and only thereafter should the bean be validated. This however does not play well with the JSF approach where a model is only updated when validation passes. But for class level validation we seemingly can not validate until the model is updated. To break this tie, a copy of the model bean is made first, and then values are stored in this copy and validated there. If validation passes, the original bean is updated.

A bean is copied using the following strategies (in the order indicated):

1. Cloning - Bean must implement the Cloneable interface and support cloning according to the rules of that interface. See CloneCopier
2. Serialization - Bean must implement the Serializable interface and support serialization according to the rules of that interface. See SerializationCopier
3. Copy constructor - Bean must have an additional constructor (next to the default constructor) taking a single argument of its own type that initializes itself with the values of that passed in type. See CopyCtorCopier
4. New instance - Bean should have a public no arguments (default) constructor. Every official JavaBean satisfies this requirement. Note that in this case no copy is made of the original bean, but just a new instance is created. See NewInstanceCopier

If the above order is not ideal, or if an custom copy strategy is needed (e.g. when it's only needed to copy a few fields for the validation) a strategy can be supplied explicitly via the copier attribute. The value of this attribute can be any of the build-in copier implementations given above, or can be a custom implementation of the Copier interface.

Author:

Bauke Scholtz, Arjan Tijms

See Also:

BeanValidationEventListener

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ValidateBean.CollectingValidator

Field Summary

Fields inherited from class javax.faces.view.facelets.TagHandler

nextHandler, tag, tagId

Constructor Summary

Constructors

Constructor and Description
ValidateBean(TagConfig config) The tag constructor.

Method Summary

Modifier and Type	Method and Description
void	apply(FaceletContext context, UIComponent parent) If the parent component has the value attribute or is an instance of UICommand or UIInput and is new and we're in the restore view phase of a postback, then delegate to processValidateBean(UIComponent).
protected void	processValidateBean(UIComponent component) Check if the given component has participated in submitting the current form or action and if so, then perform the bean validation depending on the attributes set.

Methods inherited from class javax.faces.view.facelets.TagHandler

getAttribute, getRequiredAttribute, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ValidateBean

public ValidateBean(TagConfig config)

The tag constructor.

Parameters:

config - The tag config.

Method Detail

apply

public void apply(FaceletContext context,
                  UIComponent parent)
           throws IOException

If the parent component has the value attribute or is an instance of UICommand or UIInput and is new and we're in the restore view phase of a postback, then delegate to processValidateBean(UIComponent).

Throws:

IllegalArgumentException - When the value attribute is absent and the parent component is not an instance of UICommand or UIInput.

IOException

processValidateBean

protected void processValidateBean(UIComponent component)

Check if the given component has participated in submitting the current form or action and if so, then perform the bean validation depending on the attributes set.

Parameters:

component - The involved component.

Throws:

IllegalArgumentException - When the parent form is missing.