Package org.omnifaces.taghandler

Class 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="jakarta.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}" />

    Since OmniFaces 3.8, nested properties are also supported with @jakarta.validation.Valid cascade 

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

 <o:validateBean value="#{bean}" />

    Whereby the product property looks like this:

     @Valid
 private Product product;

    When using <o:validateBean method="validateCopy" /> (which is the default), then only beans, lists, maps and arrays are considered as nested properties and the copied bean will be autopopulated with defaults. If this fails, then consider creating a custom copier as instructed in next section.

    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 Faces 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.

    If the copying strategy is not possible due to technical limitations, then you could set method attribute to "validateActual". 

     <o:validateBean value="#{bean.product}" method="validateActual" />

    This will update the model values and run the validation after update model values phase instead of the validations phase. The disadvantage is that the invalid values remain in the model and that the action method is anyway invoked. You would need an additional check for FacesContext.isValidationFailed() in the action method to see if it has failed or not.

    Faces messages

    By default, the faces message is added with client ID of the parent UIForm. 

     <h:form id="formId">
     ...
     <h:message for="formId" />
     <o:validateBean ... />
 </h:form>

    The faces message can also be shown for all invalidated components using showMessageFor="@all". 

     <h:form>
     <h:inputText id="foo" />
     <h:message for="foo" />
     <h:inputText id="bar" />
     <h:message for="bar" />
     ...
     <o:validateBean ... showMessageFor="@all" />
 </h:form>

    The faces message can also be shown as global message using showMessageFor="@global". 

     <h:form>
     ...
     <o:validateBean ... showMessageFor="@global" />
 </h:form>
 <h:messages globalOnly="true" />

    The faces message can also be shown for specific components referenced by a space separated collection of their client IDs in showMessageFor attribute. 

     <h:form>
     <h:inputText id="foo" />
     <h:message for="foo" />
     <h:inputText id="bar" />
     <h:message for="bar" />
     ...
     <o:validateBean ... showMessageFor="foo bar" />
 </h:form>

    The faces message can also be shown for components which match Property Path of the ConstraintViolation using showMessageFor="@violating", and when no matching component can be found, the message will fallback to being added with client ID of the parent UIForm. 

     <h:form id="formId">
     ...
     <!-- Unmatched messages shown here: -->
     <h:message for="formId" />
     ...
     <h:inputText id="foo" value="#{bean.product.item}" />

     <!-- Messages where ConstraintViolation PropertyPath is "item" are shown here: -->
     <h:message for="foo" />
     ...
     <o:validateBean ... value="#{bean.product}" showMessageFor="@violating" />
 </h:form>

    The showMessageFor attribute is new since OmniFaces 2.6 and it defaults to @form. The showMessageFor attribute does by design not have any effect when validateMethod="actual" is used.

    Message format

    The faces message uses a predefined message format, which corresponds to the value of BeanValidator.MESSAGE_ID in the message bundle. The default message format of {1}: {0} prepends the labels of all the validated fields. This is useful in the case of validating a single bean property, but sometimes confusing in the case of validating a bean with many properties.

    In a form containing properties like First Name, Last Name, Address, Zip Code, and Phone Number where at the bean level, at least one of the name fields must be non-null, overriding the message format can help make a more clear error message.

    This can be done by overriding the BeanValidator.MESSAGE_ID line in the message bundle: 

     jakarta.faces.validator.BeanValidator.MESSAGE = Errors encountered: {0}

    However, this change affects all bean validation messages site-wide. In case you'd like to fine-tune the bean validation message on a per-<o:validateBean>-basis, then you can since OmniFaces 3.12 use the messageFormat attribute. Any {0} placeholder will be substituted with the error message and any {1} placeholder will be substituted with the labels of all validated fields. 

     <!-- Displays: "First Name, Last Name, Address, Zip Code, Phone Number: First Name and Last Name cannot both be null" -->
 <o:validateBean />

 <!-- Displays: "Errors encountered: First Name and Last Name cannot both be null" -->
 <o:validateBean messageFormat="Errors encountered: {0}" />"
    Author:
    Bauke Scholtz, Arjan Tijms, Andre Wachsmuth
    See Also:
    BeanValidationEventListener