Project3OverwritetheMemberAdministrationSystemwiththePHPFrameworkLaravelTask7Back-endValidationMethodforSheetDatainLaravelSchoolofSoftware,ChengduPolytechnicLecturer:MuQichunBack-endValidationMethodforFormDatainLaravelThefront-endvalidationmethodforformsisaswehavedonebefore,weshouldhaveseenthiswhenweweretestingtheloginpage.Back-endvalidationofformdataisalsoveryconvenient.Laravelprovidesacompletesetofvalidationmechanismsforustouse,whichcanbefoundintheofficialdocumentation:/docs/laravel/8.5/validation/10378#e05dceLaravelprovidesavalidationclasscalledValidator,whichisbasicallyusedlikethis:Back-endValidationMethodforFormDatainLaravelSeethedocumentationfortheavailablevalidationrules:/docs/laravel/8.5/validation/10378#189a36Forexample:accepted,indicatingthatthefieldtobevalidatedmustbe"yes","on",1,ortrue.ThisisusefulwhenverifyingacceptanceofTermsofServiceorsimilarfields.alpha,indicatingthatthefieldtobevalidatedcanonlyconsistofletters.alpha_dash,indicatingthatthefieldtobevalidatedmaycontainletters,numbers,dashes(-)andunderscores(_).alpha_num,indicatingthatthefieldtobevalidatedcanonlyconsistoflettersandnumbers.Insteadofusingthevalidationrulescreateddirectlybythesystem,wecancreatemorecomplexvalidationrulesusingourownregularexpressions.Next,let'stakedatavalidationinloginasanexampletoseehowtousethedatavalidationclassinLaravel.Back-endValidationMethodforFormDatainLaravelBack-endValidationMethodforFormDatainLaravelMethodtomodifytheloginasshownontherightBack-endValidationMethodforFormDatainLaravelAsyoucanseethatwhenavalidationerroroccurs,thesystemredirectstotheloginroutewiththeparametererrors,whichcontainvariouserrorinformation.Inordertodisplayvalidationerrormessagesonthefront-endpage,youneedtoaddcorrespondingcodestotheview.Wecantestthisbyaddingthefollowingcodetologin.blade.php:Back-endValidationMethodforFormDatainLaravelForamoreconvenienttest,wetemporarilyturnofffront-enddatavalidationinlogin.blade.phpandthensubmititdirectlytoseetheerrortipsgivenbythesystem:Back-endValidationMethodforFormDatainLaravelThesecodesareusingbladetemplatesyntax,whichare@followedbykeywords.Forexample,@if,etc.Aftertheerrorhasbeenreturned,theinformationenteredbytheoriginaluserneedstobekeptintheinputboxforconvenience.It'salsoeasytodothisbyaddingthemethod“withInput()”whenthecontrollerreturnsandthenadding“value='{{old("name")}}'”tothecontrolonthefront-endpage.Back-endValidationMethodforFormDatainLaravelThroughthepreviousoperations,wecanverifytheback-endoftheformdataandseethevariouserrormessagesthatwehavedefined.Butonthefront-end,wealsoneedtolocatetheseerrormessagesandinputboxestodisplaythemmoreclearly,whichmeanstocorrespondtoaspecificformfield.Afterthefield,weaddaDOMnodethatdisplayserrormessages.Pleaserefertothefollowingcodes:Back-endValidationMethodforFormDatainLaravelThelogicissimple:usethehashmethodinerrorstodetermineiftheusernamekeyexists.Ifitdoes,concatenatethevaluescorrespondingtothekeyandthenoutput.Concatenationisusedbecausetheremaybemultipleerrormessagesassociatedwithasinglekey.Errorinformationprocessingforpasswordsandcaptchaissimilar,justrefertothesameprocessingofusername.Finally,youcanseetheresultsofalltheerrormessageprompts:SummaryValidatorisaformvalidationclassinLaravel.Usingitsownformvalidationclasscaneffectivelyimprovedevelopmentefficiency.Theback-endvalidationofformdatacanberealizedclearlyandeffectivelybymakingval