Mastering omnifaces a problem

MasteringOmniFaces
Writtenby:AnghelLeonardandConstantinAlin
Reviewedby:BaukeScholtzandArjanTijms

GlasnevinPublishing,2ndFloor,
13UpperBaggotStreet,Dublin4,Ireland
www.glasnevinpublishing.com


Thiseditionpublishedin2015byGlasnevinPublishing


©AnghelLeonardandConstantinAlin2015


All rights reserved. No part of this book may be reproduced or utilised in any form or by any means electronic or
mechanical including photography, filming, recording, video recording, photocopying, or by information storage and
retrievalsystemandshallnot,byanywayoftradeorotherwise,belent,resoldorotherwisecirculatedinanyformof
binding or cover other than that in which it is published without prior permission in writing from the publisher. The
moralrightsoftheauthorhavebeenasserted.

Alltrademarksthatappearinthebookaretrademarksoftheirrespectiveowners.Ratherthanputatrademarksymbol
after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the
trademarkowner,withnointentionofinfringementofthetrademark.Wheresuchdesignationsappearinthisbook,they
havebeenprintedwithinitialcaps.

The author and publisher of this book have used their best efforts in preparing this book. These efforts include the
development,researchandtestingofthetheoriesandcomputationalmodelsgiveninthebook.Theauthorandpublisher
make no warranty of any kind, expressed or implied, with regard to any text, models, program code or algorithms
containedinthisbook.Theauthorandpublishershallnotbeliableinanyeventforincidentalorconsequentialdamages
in connection with, or arising out of, the furnishing, performance, or use of this text, models, program code or
algorithms.

ISBN:978-1-908689-29-0


ACIPcataloguerecordforthisbookisavailablefromtheBritishLibrary

PapersusedbyGlasnevinPublishingarefromwellmanagedforestsandotherresponsiblesources.

Glasnevin Publishing books are available at special quantity discounts for use in educational courses or for use in
corporatetrainingprograms.Formoreinformation,pleaseemail




JavaTMisaregisteredtrademarkofOracleand/oritsaffiliates


Contents
Preface
AbouttheAuthors
AbouttheReviewers
Acknowledgements
Chapter1:OmniFacesComponents
1.1OutputLabel
1.2Param
1.3OutputFormat
1.4Messages
1.5OnloadScript
1.6DeferredScipt
1.7Highlight

1.8ViewParam
1.9FormandIgnoreValidationFailed
1.10Cache
1.11CommandScript
1.12ResolveComponent
1.13ResourceInclude
1.14GraphicImage
1.15ComponentIdParam
1.16MoveComponent
1.17Tree
1.18ConditionalComment

Chapter2:OmniFacesValidators
2.1JsfLabelMessageInterpolator
2.2ValueChangeValidatorandValueChangeConvertor
2.3RequiredCheckboxValidator
2.4.ValidateBean
2.5ValidateUniqueColumn
2.6ValidateXxx

Chapter3:OmniFAcesTagHandlers
3.1Convertor/Validator
3.2ImportConstants/ImportFunctions


3.3ViewParamValidationFailed
3.4EnableRestorableView
3.5MassAttribute
3.6MethodParam
3.7TagAttribute

Chapter4:OmniFacesConvertors
4.1GenericEnumConvertor
4.2SelectItemsConvertorandSelectItemsIndexConvertor

Chapter5:OmniFacesExceptionHandlers
5.1FullAjaxExceptionHandler
5.2FacesMessageExceptionHandler

Chapter6:OmniFacesContexts
6.1OmniPartialViewContext

Chapter7:OmniFacesResourceHandlers
7.1CDNResourceHandler
7.2UnmappedResourceHandler
7.3CombinedResourceHandler

Chapter8:OmniFacesEventListeners
8.1.InvokeActionEventListener
8.2ResetInputAjaxActionListener

Chapter9:OmniFacesViewHandlers
9.1NoAutoGeneratedIdViewHandler

Chapter10:There’sMore!

Preface

OmniFaces is a utility library for JSF and a comprehensive compendium of
programmingtechniques,designpatternsandrecipesforJSFdevelopers.

MasteringOmniFaces is targeted towards JSF page authors/developers that wish to use
OmniFacesintheirprojectsandJSFdevelopersinterestedingoingdeepintotheJSFAPI
“bowels”inordertobecomerealJSFmasters.
When confronted with “unusual” JSF tasks (e.g. fixing bugs, solve gaps, avoiding
pitfalls,etc.)weoftendon’thaveenoughselfconfidencethatwearetherightpersonto
completethetask,soweaskforprofessionalhelpindifferentcommunitiesor“question
and answer sites”, such as StackOverflow. StackOverflow isn’t just casually mentioned
here,asitseemsthattheOmniFacesprojectideawas“born”asaprofessionalandunitary
answer to the most popular questions/bugs/gaps reported on this site. The professionals
that picked up those reports from StackOverflow and answered/solved them via the
OmniFacesprojectareBaukeScholtzandArjanTijms.BothScholtzandTijmsareJSF
ExpertGroupmembersdirectlyinvolvedinJSFdevelopment.Theyconstantly“scan”the
JSFworldfornewlyreportedissuesandarealwaysopentoreceivenewideas/suggestions
for improving OmniFaces and JSF. In this way, OmniFaces is always up to date and is
continuouslygettingbetter.Moreover,OmniFacesisavailableundertheApacheLicense
2.0,soitmaybefreelyused,distributed,andmodified.



In this book, we “dissect” OmniFaces 2.1 and we extract valuable lessons that will
definitelygiveyouaboostintheJSFfield.Afteryouhavereadthisbook,youwillsay
Wow,IknewsolittleaboutJSFbefore!Now,I’mabletosolvetasksthatIdidn’thavea
clueaboutinthepast!

Asyouwillsee,however,itisnoteasytoreachahighlevelofJSFknowledge.Not


everything will be easy to understand and assimilate, and many advanced techniques
requirehardwork,patience,creativityandperseverance.Wheneveryouarereallystuckor
youhaveabrilliantideaofhowtoimprovetheOmniFacesproject,justcontactususing
theinformationintheContact/Questionssubsectionbelow.
Whilereadingthisbook,itwouldbegreattoalsofollowthepointedreferences.These
referencescomefrom andtheycoverdifferentJSFfundamentalsthat
couldn’tbecoveredinthebook.Theyaremeanttosupplymandatoryinformationinorder
tounderstandaspecifictopic.Moreover,theOmniFacesutilitiesreferences(alsocovered
on ) are important to understand the OmniFaces shortcuts and to
seriously increase your collection of JSF helpers. For convenience, we have all these
referencescollectedinaZEEFpageavailableat .



Whoisthisbookfor?
MasteringOmniFacesisabookforanyJSFdeveloper.Fromnovicetoexpert,anyJSF
developerwillfindvaluablelessonsandtechniquesmeanttotakeJSFprojectstoahigher
levelofimplementationandrobustness.Fornewcomers,thisbookwillbeagreatguide
that will help them to learn JSF in a “healthy” manner and will answer many specific
novicequestions.ForJSFdevelopers,whohavepreviousJSFexperiencebutarelacking
anunderstandingofbestpracticesandastandardmethodsofimplementingfunctionality,
thisbookwillbelikea“goldmine”.



Whatthisbookcovers
Thebookisdividedintothreepartsandtenchaptersasfollows:

PARTI-thispartcontainsfourchaptersstructuredinsections.Eachsectionisdedicated
to an OmniFaces artifact “dissected” into seven subsections: Theoretical aspects,
Problem/Issue,BrainstormingJSF,OmnifyBrainstorming,HowitWorks,Conclusionand
SectionHighlights.


Chapter1-OmniFacesComponents
Fromthischapteryoucancollectasetofrecipesandtechniquesforwritingavarietyof
customcomponents.Youwilllearnhowtowritefamiliesofcomponents,extendexisting
components, suppressing/adding specific functionalities, writing custom renderers, etc.
Chapter1covers:

Cache

server-sidecacheofrenderedmarkup

CommandScript

generateaJSfunctionintheglobalJSscope

ComponentIdParam

renderjustoneormorecomponentsona
viewviaaGETparameter

ConditionalComment

rendersaconditionalcomment(specificto

IE)

DeferredScript

defertheloadingofthegivenscriptresource
tothewindowloadevent

Form

keepvieworrequestparametersinthe
requestURLafterapost-back

IgnoreValidationFailed

ignorevalidationfailures(invokeaction
phasewillbeexecutedanyway)

GraphicImage

loadimagesfrom byte[] / InputStream /SVG
(optionalasdataURI)

Highlight

highlightsallinvalid UIInput componentsand
theassociatedlabels

Messages

multiple for ,singlemessage,HTML

escaping,Iterationmarkupcontrol

MoveComponent

movecomponents,facetsandbehaviorsat


runtime
OnloadScript

executeitsscriptbodyoneveryAJAX
request

OutputFormat

capturingtheoutputandexposingitintothe
requestscope

OutputLabel

setitsvalueasthelabelofthecomponent
pointedbyits for attribute

Param

supporta Converter toconvertthesupplied
valuetostring

ResolveComponent

putinFacelet/requestscopeareferencetoa
component

ResourceInclude

catchtheoutputfromaJSP/Servletand
renderittotheJSFwriter

Tree

fullcontroloverthemarkupofatree
hierarchy

ViewParam

stateless <f:viewParam>




Chapter2-OmniFacesValidators
AsaJSFdeveloper,youhaveprobablyusedtheJSFbuilt-invalidatorsandwroteseveral
customvalidatorsconformingtoJSFstandards.Thischapterwilltakeyoutoanotherlevel
of implementing validators. Amongst other things, you will see how to write a message
interpolator, and how to implement cross-field validators, which are not supported by
defaultinJSF.Chapter2covers:


JsfLabelMessageInterpolator

alabelcanappearinthemiddleofa
beanvalidationmessage

RequiredCheckboxValidator

solverequired=“true” attributeand
UISelectBoolean issue

ValueChangeValidator

validateonlywhenthesubmittedvalue
isreallychanged

validateAll


validatesifALLUIInput shavebeen
filledout

validateAllOrNone

validatesifALL/NONEUIInput shave
beenfilledout


validateEqual

validatesifALL UIInput shavethesame
value

validateMultiple

validatemultiplefieldsbyeithera
customvalidatormethod

validateOne

validatesifONLYONE UIInput have
beenfilledout

validateOneOrMore

validatesifatleastONE UIInput hasbeen
filledout

validateOneOrNone

validatesifONLYONE/NONE UIInput
hasbeenfilledout

validateOrder

validatesifthe UIInput svaluesrespecta
specifiedorder

validateUnique

validatesifALL UIInput shaveanunique
value

validateUniqueColumn

validatesifthe UIInput valueinan UIData
isuniqueinallrows

validateBean

beanvalidationonaperUICommand / UIInput componentbasis,as
wellasvalidatingagivenbeanatthe
classlevel


Chapter3-OmniFacesTagHandlers
WhenaJSFdeveloperwriteshisfirstclassicaltaghandler,wecansaythathehasreached
a “decent” level of JSF knowledge. It is a well-known fact that tag handlers are a
milestoneinaJSFdeveloper’sevolution.TheOmniFacestaghandlersaremeantto“blow
yourmind”and,toparaphraseafamousTVserial,to“boldlygowherenomanhasgone
before”.Chapter3covers:



converter

supportfordeferredvalueexpressionsin
allconverterattributes

enableRestorableView

recreatetheentireviewwheneverthe
viewhasbeenexpired

ignoreValidationFailed

ignorevalidationfailureswhen
executingan UICommand action

importConstants

mapconstantsofthegivenFQNofa
typeintherequestscope

importFunctions

mapfunctionsofthegivenFQNofa
typeinthe“Faceletscope”

massAttribute

setsanattributeofthegivennameand
valueonallnestedcomponents

methodParam

passamethodexpressionasattribute
intoaFaceletstag

tagAttribute

explicitlydeclareatagattributeona
Faceletstagfile

validator

supportfordeferredvalueexpressionsin
allvalidatorattributes

viewParamValidationFailed

handleviewparametervalidationfailure
viaredirectorHTTPerrorcode


Chapter4-OmniFacesConverters
OmniFacesrevealsseveraladvancedconverterswhichsolvesomeJSFgapsthatcontinue
topersistoverJSFmilestonereleases.Chapter4covers:

ListIndexConverter

convertsbasedontheposition(index)of
theselectediteminthelist

ListConverter

workdirectlyviaa List of
entities(cannotuse ListIndexConverter )

SelectItemsConverter

automativallyconvert <f:selectItems>
entities

SelectItemsIndexConverter

asSelectItemsConverter, butconvertsbased
ontheposition(index)

ValueChangeConverter

convertonlywhenthesubmittedvalue
haschanged

GenericEnumConverter

usein UISelectMany componentswhose
valueisbeenboundtoa List<E> property
where E isanenum



PARTII-thispartcontainsfourchaptersstructuredinsections.Eachsectionisdedicated
toanOmniFacesartifact“dissected”infoursubsections:BriefOverview,HowitWorks,
ConclusionandSectionHighlights.


Chapter5-OmniFacesExceptionHandlers
Asyouprobablyknow,treatingexceptionsthatoccurduringAJAXrequestsisarealissue
in JSF. OmniFaces provides a powerful exception handler especially for capturing and
treatingsuch“silent”exceptionsinafriendlymanner.Chapter5covers:

FacesMessageExceptionHandler

addeveryexceptionasa
global FATAL facesmessage

FullAjaxExceptionHandler

handleexceptionsduringAJAX
requestsasnon-AJAXones

Chapter6-OmniFacesContexts
Think about how many times you have written a JSF custom context or a JSF custom
partial view context? If these questions sound interesting to you, then is time to jump
“faster than a cheetah with a jetpack” to OmniPartialViewContext implementation. Chapter 6
covers:

OmniPartialViewContext

extends and improves the standard
partialviewcontext



Chapter7-OmniFacesResourceHandlers
JSF resource handlers are definitely not exploited at full capacity by JSF developers. It
istrue that after we learn about the JSF /resources contract and understand a few aspects
about JSF resources loading and caching, we have that warm fuzzy feeling that we are
pretty good with resource handlers. But, how about loading resources from a CDN

repository,combiningresourcesinasinglerequestorusingunmappedresources?So,read
chapter7andthinkagain!Chapter7covers:

CDNResourceHandler

provide CDN URLs instead of the
defaultlocalURLsforJSFresources

CombinedResourceHandler

create a combined resource for all
scriptsandoneforallstylesheets

UnmappedResourceHandler

map JSF resources on an URL pattern
of /javax.faces.resource/*




Chapter8-OmniFacesEventListeners
UnderstandingJSFeventlistenersisamandatoryskillinaJSFdeveloper’sarsenal.This
chapter will really help you to get the missing puzzle pieces of how event listeners are
working.Forexample,ifyouneversawaJSFartifactthatcanactasanactionlisteneror
asaphaselistener,dependingonhowitisconfiguredintheapplication,thenthischapter
isforyou.Chapter9covers:

InvokeActionEventListener

new <f:event> types preInvokeAction / postInvokeAction

ResetInputAjaxActionListener

resetinputfieldswhicharenotexecuted
duringAJAXsubmit,butwhichare
rendered/updatedduringAJAXresponse


Chapter9-OmniFacesViewHandlers
HavingsolidknowledgeaboutJSFviewhandlersislikehavingaprofessionalmulti-tool,
because through a view handler you can handle the processes that involves the current
view, like initializing, restoring, rendering, etc. Contrary to its many usages, JSF
developersareprettyreservedinwritingcustomviewhandlersortheywritethemforthe
wrong purposes, like dealing with components. OmniFaces provides a really useful and
correctusecase.Chapter9covers:

NoAutoGeneratedIdViewHandler




doesn’tallowauto-generatedIDs
( j_id... )


PARTIII - this part presents a brief overview of the OmniFaces artifacts that were not
presented in detail in this book. The final words are dedicated to the upcoming JSF 2.3
andOmniFaces3.0releases.

Chapter10-There’smore
CDI,FacesViews,Filters,ManagedBeans,RenderKits,Scripts,Functions



Whatyouneedforthisbook
The source code in this book comes as Maven projects developed via NetBeans and
EclipseIDEs.Fortestingthesourcecodeofthisbookyouwillneed:

NetBeans(recommended8.0)/Eclipse(recommendedEclipseMars)
WildFly(recommended8.2)/GlassFish(recommended4.1)
JSF2.2(recommendedlatestversionofMojarraorApacheMyFaces)
OmniFaces2.1or2.2(addedviaPOMfile)
occasionally:PrimeFaces(recommended5.0,addedviaPOMfile),HTTPClient
(recommended4.3.6,addedviaPOMfile)



CustomerSupport
Beside the book content, we offer you several things that will help you to enjoy
OmniFaces,asfollows:



SourceCode
ThesourcecodeforthisbookcanbedownloadedfromthefollowingGitHubrepositories:

-forNetBeansIDE
-forEclipseIDE

IsalsoveryimportanttokeepinmindtheOmniFacesShowcase,whichisarichresource
ofpracticalexamplesforOmniFacesartifactsandisavailableat:

/>




OmniFacesUtilitiesReference
OmniFacescomeswithaconsiderablenumberofutilities(helper)methodswhichsimply
cannotbedescribedinthebook.Eachofthesemethods,however,isexemplifiedonJSF
&OmniFacesFansblog,at: . Thiscanbeaccessedeasilyviathetop
menuoftheblog:



Ifyoufindthismenuhardtofollow/use,youcanalsochecktheZEEFpage,OmniFaces
Utilities, .




OtherReferences
IsveryimportanttounderstandtheJSFfundamentalswhichrepresentthe“bricks”used
by OmniFaces to build new artifacts. Instead of exploring the Internet by yourself (of
course,youarefreetodoso),wetriedtohelpyouwithaunitaryresourceofarticlesand
postsonJSF&OmniFacesFansblog,at: .TheyarealllistedonZEEF
page, ,andmentionedinthebookatspecifictopics.

Youalsomaywanttocheck: />

KeepInformationaboutOmniFacesEvolution
You can always keep informed about OmniFaces evolution on the OmniFaces website,
wikipediapage,andrecentcommitsat:
/> /> />


Contact/Questions
Foranyrelatedquestion,youcancontacttheauthorsat:



/>

IfyouhavespecificprogrammingproblemsorquestionsrelatedtotheOmniFaceslibrary,
feelfreetopostaquestiononStackOverflowusingatleastthe jsf and omnifaces tags.Ifyou
have found bugs or have new ideas, feel free to open a new issue. If you have general
feedback that’s not either a question, bug report or feature request, or if you have a
review/rating,pleasefeelfreetoleaveitat Devrates or Ohloh .


Ifyouneedtocontactthebookpublisher: