org.omnifaces.validator

Class ValueChangeValidator

java.lang.Object

org.omnifaces.validator.ValueChangeValidator

All Implemented Interfaces:

EventListener, javax.faces.validator.Validator

public abstract class ValueChangeValidator
extends Object
implements javax.faces.validator.Validator

By default, JSF validators run on every request, regardless of whether the submitted value has changed or not. In case of validation against the DB on complex objects which are already stored in the model in a broader scope, such as the view scope, this may result in unnecessarily expensive service/DAO calls. In such case, you'd like to perform the expensive service/DAO call only when the submitted value is really changed as compared to the model value.

This validator offers you a template to do it transparently. To use it, just change your validators from:

 public class YourValidator implements Validator {

     public void validate(FacesContext context, UIComponent component, Object submittedValue) {
         // ...
     }

 }
 

to

 public class YourValidator extends ValueChangeValidator {

     public void validateChangedObject(FacesContext context, UIComponent component, Object submittedValue) {
         // ...
     }

 }
 

So, essentially, just replace implements Validator by extends ValueChangeValidator and rename the method from validate to validateChangedObject.

Since:

1.7

Author:

Juliano, Bauke Scholtz

Field Summary

Fields inherited from interface javax.faces.validator.Validator

NOT_IN_RANGE_MESSAGE_ID

Constructor Summary

Constructors

Constructor and Description
ValueChangeValidator()

Method Summary

Methods

Modifier and Type	Method and Description
void	validate(javax.faces.context.FacesContext context, javax.faces.component.UIComponent component, Object submittedValue) If the component is an instance of EditableValueHolder and its old object value is equal to the submitted value, then return immediately from the method and don't perform any validation.
abstract void	validateChangedObject(javax.faces.context.FacesContext context, javax.faces.component.UIComponent component, Object submittedValue) Use this method instead of validate(FacesContext, UIComponent, Object) if you intend to perform the validation only when the submitted value is really changed as compared to the model value.

Methods inherited from class java.lang.Object

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

Constructor Detail

ValueChangeValidator

public ValueChangeValidator()

Method Detail

validate

public void validate(javax.faces.context.FacesContext context,
            javax.faces.component.UIComponent component,
            Object submittedValue)

If the component is an instance of EditableValueHolder and its old object value is equal to the submitted value, then return immediately from the method and don't perform any validation. Otherwise, invoke validateChangedObject(FacesContext, UIComponent, Object) which may in turn do the necessary possibly expensive DAO operations.

Specified by:

validate in interface javax.faces.validator.Validator

validateChangedObject

public abstract void validateChangedObject(javax.faces.context.FacesContext context,
                         javax.faces.component.UIComponent component,
                         Object submittedValue)

Use this method instead of validate(FacesContext, UIComponent, Object) if you intend to perform the validation only when the submitted value is really changed as compared to the model value.

Parameters:

context - The involved faces context.

component - The involved UI component.

submittedValue - The submitted value.