KEY REQUEST.docx

KEY REQUEST.docx

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KEYREQUEST

1LocationsforInitializationCode

Railsoffersfourstandardspotstoplaceinitializationcode:

∙config/application.rb

∙Environment-specificconfigurationfiles

∙Initializers

∙After-initializers

2RunningCodeBeforeRails

IntherareeventthatyourapplicationneedstorunsomecodebeforeRailsitselfisloaded,putitabovethecalltorequire'rails/all'inconfig/application.rb.

3ConfiguringRailsComponents

Ingeneral,theworkofconfiguringRailsmeansconfiguringthecomponentsofRails,aswellasconfiguringRailsitself.Theconfigurationfileconfig/application.rbandenvironment-specificconfigurationfiles（suchasconfig/environments/production.rb）allowyoutospecifythevarioussettingsthatyouwanttopassdowntoallofthecomponents.

Forexample,thedefaultconfig/application.rbfileincludesthissetting:

config.filter_parameters+=[:

password]

ThisisasettingforRailsitself.IfyouwanttopasssettingstoindividualRailscomponents,youcandosoviathesameconfigobjectinconfig/application.rb:

config.active_record.observers=[:

hotel_observer,:

review_observer]

RailswillusethatparticularsettingtoconfigureActiveRecord.

3.1RailsGeneralConfiguration

∙config.after_initializetakesablockwhichwillberanafterRailshasfinishedinitializingtheapplication.Thatincludestheinitializationoftheframeworkitself,plugins,engines,andalltheapplication’sinitializersinconfig/initializers.Usefulforconfiguringvaluessetupbyotherinitializers:

config.after_initializedo

  ActionView:

:

Base.sanitized_allowed_tags.delete'div'

end

∙config.allow_concurrencyshouldbetruetoallowconcurrent（threadsafe）actionprocessing.Falsebydefault.Youprobablydon’twanttocallthisonedirectly,though,becauseaseriesofotheradjustmentsneedtobemadeforthreadsafemodetoworkproperly.Canalsobeenabledwiththreadsafe!

.

∙config.asset_hostsetsthehostfortheassets.UsefulwhenCDNsareusedforhostingassets,orwhenyouwanttoworkaroundtheconcurrencyconstraintsbuiltininbrowsersusingdifferentdomainaliases.Shorterversionofconfig.action_controller.asset_host.

∙config.asset_pathletsyoudecorateassetpaths.Thiscanbeacallable,astring,orbenilwhichisthedefault.Forexample,thenormalpathforblog.jswouldbe/javascripts/blog.js,letthatabsolutepathbepath.Ifconfig.asset_pathisacallable,Railscallsitwhengeneratingassetpathspassingpathasargument.Ifconfig.asset_pathisastring,itisexpectedtobeasprintfformatstringwitha%swherepathwillgetinserted.Ineithercase,Railsoutputsthedecoratedpath.Shorterversionofconfig.action_controller.asset_path.

config.asset_path=proc{|path|"/blog/public#{path}"}

Theconfig.asset_pathconfigurationisignorediftheassetpipelineisenabled,whichisthedefault.

∙config.autoload_once_pathsacceptsanarrayofpathsfromwhichRailswillautoloadconstantsthatwon’tbewipedperrequest.Relevantifconfig.cache_classesisfalse,whichisthecaseindevelopmentmodebydefault.Otherwise,allautoloadinghappensonlyonce.Allelementsofthisarraymustalsobeinautoload_paths.Defaultisanemptyarray.

∙config.autoload_pathsacceptsanarrayofpathsfromwhichRailswillautoloadconstants.Defaultisalldirectoriesunderapp.

∙config.cache_classescontrolswhetherornotapplicationclassesandmodulesshouldbereloadedoneachrequest.Defaultstotrueindevelopmentmode,andfalseintestandproductionmodes.Canalsobeenabledwiththreadsafe!

.

∙config.action_view.cache_template_loadingcontrolswhetherornottemplatesshouldbereloadedoneachrequest.Defaultstowhateverissetforconfig.cache_classes.

∙config.cache_storeconfigureswhichcachestoretouseforRailscaching.Optionsincludeoneofthesymbols:

memory_store,:

file_store,:

mem_cache_store,oranobjectthatimplementsthecacheAPI.Defaultsto:

file_storeifthedirectorytmp/cacheexists,andto:

memory_storeotherwise.

∙config.colorize_loggingspecifieswhetherornottouseANSIcolorcodeswhenlogginginformation.Defaultstotrue.

∙config.consider_all_requests_localisaflag.IftruethenanyerrorwillcausedetaileddebugginginformationtobedumpedintheHTTPresponse,andtheRails:

:

Infocontrollerwillshowtheapplicationruntimecontextin/rails/info/properties.Truebydefaultindevelopmentandtestenvironments,andfalseinproductionmode.Forfiner-grainedcontrol,setthistofalseandimplementlocal_request?

incontrollerstospecifywhichrequestsshouldprovidedebugginginformationonerrors.

∙config.dependency_loadingisaflagthatallowsyoutodisableconstantautoloadingsettingittofalse.Itonlyhaseffectifconfig.cache_classesistrue,whichitisbydefaultinproductionmode.Thisflagissettofalsebyconfig.threadsafe!

.

∙config.eager_load_pathsacceptsanarrayofpathsfromwhichRailswilleagerloadonbootifcacheclassesisenabled.Defaultstoeveryfolderintheappdirectoryoftheapplication.

∙config.encodingsetsuptheapplication-wideencoding.DefaultstoUTF-8.

∙config.filter_parametersusedforfilteringouttheparametersthatyoudon’twantshowninthelogs,suchaspasswordsorcreditcardnumbers.

∙config.force_sslforcesallrequeststobeunderHTTPSprotocolbyusingRack:

:

SSLmiddleware.

∙config.log_leveldefinestheverbosityoftheRailslogger.Thisoptiondefaultsto:

debugforallmodesexceptproduction,whereitdefaultsto:

info.

∙config.loggeracceptsaloggerconformingtotheinterfaceofLog4rorthedefaultRubyLoggerclass.DefaultstoaninstanceofActiveSupport:

:

BufferedLogger,withautoflushingoffinproductionmode.

∙config.middlewareallowsyoutoconfiguretheapplication’smiddleware.ThisiscoveredindepthintheConfiguringMiddlewaresectionbelow.

∙config.pluginsacceptsthelistofpluginstoload.Thedefaultisnilinwhichcaseallpluginswillbeloaded.Ifthisissetto[],nopluginswillbeloaded.Otherwise,pluginswillbeloadedintheorderspecified.Thisoptionletsyouenforcesomeparticularloadingorder,usefulwhendependenciesbetweenpluginsrequireit.Forthatusecase,putfirstthepluginsyouwanttobeloadedinacertainorder,andthenthespecialsymbol:

alltohavetherestloadedwithouttheneedtospecifythem.

∙config.preload_frameworksenablesordisablespreloadingallframeworksatstartup.Enabledbyconfig.threadsafe!

.Defaultstonil,soisdisabled.

∙config.reload_pluginsenablesordisablespluginreloading.Defaultstofalse.

∙config.secret_tokenusedforspecifyingakeywhichallowssessionsfortheapplicationtobeverifiedagainstaknownsecurekeytopreventtampering.Applicationsgetconfig.secret_tokeninitializedtoarandomkeyinconfig/initializers/secret_token.rb.

∙config.serve_static_assetsconfiguresRailsitselftoservestaticassets.Defaultstotrue,butintheproductionenvironmentisturnedoffastheserversoftware（e.g.NginxorApache）usedtoruntheapplicationshouldservestaticassetsinstead.Unlikethedefaultsettingsetthistotruewhenrunning（absolutelynotrecommended!

）ortestingyourappinproductionmodeusingWEBrick.Otherwiseyouwon´tbeableusepagecachingandrequestsforfilesthatexistregularlyunderthepublicdirectorywillanywayhityourRailsapp.

∙config.session_storeisusuallysetupinconfig/initializers/session_store.rbandspecifieswhatclasstousetostorethesession.Possiblevaluesare:

cookie_storewhichisthedefault,:

mem_cache_store,and:

disabled.ThelastonetellsRailsnottodealwithsessions.Customsessionstorescanalsobespecified:

config.session_store:

my_custom_store

ThiscustomstoremustbedefinedasActionDispatch:

:

Session:

:

MyCustomStore.Inadditiontosymbols,theycanalsobeobjectsimplementingacertainAPI,likeActiveRecord:

:

SessionStore,inwhichcasenospecialnamespaceisrequired.

∙config.threadsafe!

enablesallow_concurrency,cache_classes,dependency_loadingandpreload_frameworkstomaketheapplicationthreadsafe.

ThreadsafeoperationisincompatiblewiththenormalworkingsofdevelopmentmodeRails.Inparticular,automaticdependencyloadingandclassreloadingareautomaticallydisabledwhenyoucallconfig.threadsafe!

.

∙config.time_zonesetsthedefaulttimezonefortheapplicationandenablestimezoneawarenessforActiveRecord.

∙config.whiny_nilsenablesordisableswarningswhenacertainsetofmethodsareinvokedonnilanditdoesnotrespondtothem.Defaultstotrueindevelopmentandtestenvironments.

3.2ConfiguringAssets

Rails3.1,bydefault,issetuptousethesprocketsgemtomanageassetswithinanapplication.Thisgemconcatenatesandcompressesassetsinordertomakeservingthemmuchlesspainful.

∙config.assets.enabledaflagthatcontrolswhethertheassetpipelineisenabled.Itisexplicitlyinitializedinconfig/application.rb.

∙pressaflagthatenablesthecompressionofcompiledassets.Itisexplicitlysettotrueinconfig/production.rb.

∙config.assets.css_compressordefinestheCSScompressortouse.Itissetbydefaultbysass-rails.Theuniquealternativevalueatthemomentis:

yui,whichusestheyui-compressorgem.

∙config.assets.js_compressordefinestheJavaScriptcompressortouse.Possiblevaluesare:

closure,:

uglifierand:

yuiwhichrequiretheuseoftheclosure-compiler,uglifieroryui-compressorgemsrespectively.

∙config.assets.pathscontainsthepathswhichareusedtolookforassets.Appendingpathstothisconfigurationoptionwillcausethosepathstobeusedinthesearchforassets.

∙config.assets.precompileallowsyoutospecifyadditionalassets