Data::Verifier and Message::Stack
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Data::Verifier and Message::Stack

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Revitalizing the forgotten bits of your web application. Given at Perl Oasis 2010 in Orlando, Florida on January 16th.

Revitalizing the forgotten bits of your web application. Given at Perl Oasis 2010 in Orlando, Florida on January 16th.

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  • 1. DATA::VERIFIER & MESSAGE::STACK Invigorating The Forgotten Bits Of Your Web App
  • 2. CORY G WATSON: GPHAT • Magazines.com: Group Director, Development • Cold Hard Code: Creative Director • Contributor and Color Commentator on various projects.
  • 3. BIASES: I HAVE THEM • I’m a closet designer • I hate All-In-One Form handlers • Messaging & Validation are not sexy
  • 4. VALIDATION: PRIMER • Client side is advancing. • It won’t replace server side.* • Duplication of effort.
  • 5. VALIDATION: DATA::FORMVALIDATOR • 8+ years old • Big, Complex
  • 6. DATA::VERIFIER
  • 7. D:V – FEATURES • Reusable constraints and coercion • Required, optional & dependents • Length checking • Global and per-field filters
  • 8. MOOSE
  • 9. WHY MOOSE? • Simplicity • Type Constraints • Coercion • Serialization
  • 10. GETTING STARTED my $dv = Data::Verifier->new(…); my $results = $dv->verify(%params); if($results->success) { # o/ } else { # :( }
  • 11. PROFILE profile => %fields • Simple HashRef • A key for each field • Opposite of D:FV, fields before required/optional
  • 12. FIELD KEYS • coerce • min_length • coercion • post_check • dependent • required • filters • type • max_length
  • 13. EASY ONES • required: Optional? Then it’s not required! • max_length => $x • min_length => $y • type => $moose_type
  • 14. EXAMPLE filters => [ qw(trim) ], profile => { email => { min_length => 5 type => EmailAddress, required => 1 } }
  • 15. COERCE • Same as Moose’s coerce flag • true tells D:V to use Moose coercions • Occludes coercion
  • 16. COERCION • Allows one-off coercions • Does not define a global Moose coercion • Saves cluttering your ::Types with coercions
  • 17. COERCION (CONT) coercion => Data::Verifier::coercion( from => ‘Int’, via => sub { DateTime->from_epoch(epoch => $_) } )
  • 18. DEPENDENT • Field A depends on Field B • More? Field A can depend on an entire profile. • Creates a new D:V, verifies it, merges it with this one.
  • 19. DEPENDENT password => { dependent => { password2 => { required => 1 } } }
  • 20. FILTERS filters => [ qw(trim) ] • Comes with some built-ins. • Also allows CodeRefs • Global and per-field
  • 21. POST_CHECK • Checked at end of verification. • Accepts a CodeRef • Given Results object as argument. • $password1 eq $password2 scenarios
  • 22. POST_CHECK (CONT) post_check => sub { my ($r) = @_; return $r->get_value(‘pass1’) eq $r->get_value(‘pass2’); }
  • 23. RESULT METHODS • get_original_value # unmodified • get_value # filters, coercions • is_missing, is_valid • More!
  • 24. SERIALIZATION • MooseX::Storage • caveat: value isn’t serialized, arbitrary type • use get_original_value • validity and missing is retained
  • 25. MESS-AGING • Error variable • Error ArrayRef • Error plugin?
  • 26. MESSAGING • Context • Level • Localization
  • 27. MESSAGE • id: Localization • level: ‘error’, ‘info’ • params: [ ‘gphat@coldhardcode’ ] • scope: ‘login_form’ • subject: ‘email’ • text: ‘Invalid email address.’
  • 28. MESSAGE::STACK
  • 29. MESSAGE::STACK • List of messages • Order is retained • Convenience methods • Many methods return sub-Stacks
  • 30. ADD A MESSAGE $stack->add( id => ‘invalid_email’, scope => ‘login_form’, subject=> ‘email’, level => ‘error’ );
  • 31. BEING INFORMED • count • id, level, scope, subject • has_* (boolean) • for_* (subset Message::Stack)
  • 32. Error Message! Error Message! Line Item 1 Line Item 1 Delivery Options Gift Options Line Item 2 Line Item 2 Delivery Options Gift Options CRAPPY FORM: WHERE ARE
  • 33. Error Message! Line Item 1 Line Item 1 Delivery Options Gift Options Error Message! Line Item 2 Line Item 2 Delivery Options Gift Options GOOD FORM: PRECISE
  • 34. METHODS • Errors: for_level(‘error’); • Sub-Form: for_scope(‘line-item1’); • Specific field: has_subject(‘email’); • Cat: c.loc(message.id, message.params)
  • 35. HINTS • Templates can get messy. • Works well with macros. • Use a lot or a little. • foreach($stack->messages)
  • 36. DATA::VERIFIER + MESSAGE::STACK
  • 37. DATA::MANAGER
  • 38. DATA::MANAGER my $dm = Data::Manager->new; my $v = Data::Verifier->new...; $dm->set_verifier(‘foo’, $v); $dm->verify(‘foo’, { ... }); my $res => $dm->get_results(‘foo’);
  • 39. DATA::MANAGER (CONT) • A single Message::Stack • Multiple Data::Verifier objects (scopes) • success • messages_for_scope
  • 40. SUMMARY • Simplified validation • Reusable types • Serialization for redirects. • Messaging is important. • Context, context, context!
  • 41. QUESTIONS?
  • 42. COLOPHON • Titling: Tungsten 72pt, Hoefler & Frere-Jones • Body: Hoefler Text 38pt, Hoefler & Frere-Jones • Diagrams: OmniGraffle, The Omni Group • Presentation: Keynote ’09, Apple, Inc • Theme: Modified “Showroom”