1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
2 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
4 <html xmlns="http://www.w3.org/1999/xhtml">
7 <title>DBIx::Class (aka DBIC)</title>
9 <meta name="contributor" content="youcan[64]netzgesta[46]de" />
10 <meta name="publisher" content="s5.netzgesta.de" />
11 <meta name="description" content="S5 1.3 is a very flexible and lightweight slide show system available for anyone to use (including transitions and scalable fonts and images)" />
12 <meta name="keywords" content="S5, version 1.3, slide show, presentation-mode, projection-mode, powerpoint-like, scala-like, keynote-like, incremental display, scalable fonts, scalable images, transitions, notes, osf, xoxo, css, javascript, xhtml, public domain" />
14 <meta name="generator" content="S5" />
15 <meta name="version" content="1" />
16 <meta name="subject" content="DBIx::Class" />
17 <meta name="author" content="See first slide" />
18 <meta name="company" content="N/A" />
19 <meta name="robots" content="index, follow" />
20 <meta name="revisit-after" content="7 days" />
21 <!-- meta additionally -->
22 <meta http-equiv="content-type" content="text/html; charset=utf-8" />
23 <meta http-equiv="Content-Script-Type" content="text/javascript" />
24 <meta http-equiv="Content-Style-Type" content="text/css" /><!-- configuration parameters -->
25 <meta name="defaultView" content="slideshow" />
26 <meta name="controlVis" content="hidden" />
27 <!-- configuration transition extension -->
28 <meta name="tranSitions" content="true" />
29 <meta name="fadeDuration" content="500" />
30 <meta name="incrDuration" content="250" />
31 <!-- configuration autoplay extension -->
32 <meta name="autoMatic" content="false" />
33 <meta name="playLoop" content="true" />
34 <meta name="playDelay" content="10" />
35 <!-- configuration audio extension -->
36 <meta name="audioSupport" content="false" />
37 <meta name="audioVolume" content="0" />
38 <meta name="audioError" content="false" />
39 <!-- configuration audio debug -->
40 <meta name="audioDebug" content="false" />
41 <!-- style sheet links -->
42 <link rel="stylesheet" href="ui/scala_utf/slides.css" type="text/css" media="projection" id="slideProj" />
43 <link rel="stylesheet" href="ui/scala_utf/outline.css" type="text/css" media="screen" id="outlineStyle" />
44 <link rel="stylesheet" href="ui/scala_utf/print.css" type="text/css" media="print" id="slidePrint" />
45 <link rel="stylesheet" href="ui/scala_utf/opera.css" type="text/css" media="projection" id="operaFix" />
46 <!-- embedded styles -->
47 <style type="text/css" media="all">
48 .imgcon {width: 100%; margin: 0 auto; padding: 0; text-align: center;}
49 #anim {width: 33%; height: 320px; position: relative;}
50 #anim img {position: absolute; top: 0px; left: 0px;}
55 <script src="ui/scala_utf/slides.js" type="text/javascript"></script>
60 <div id="controls"><!-- DO NOT EDIT --></div>
61 <div id="currentSlide"><!-- DO NOT EDIT --></div>
62 <div id="header"></div>
64 <h1>DBIx::Class Introduction</h1>
65 <h2>YAPC::NA 2010</h2>
69 <div class="presentation">
72 <h1>DBIX::Class (aka DBIC)</h1>
73 <h3>for (advanced) beginners</h3>
78 <h4>Originally Leo Lapworth @ LPW 2009</h4>
79 <h4>Matthew S. Trout</h4>
80 <h4>Justin D. Hunter</h4>
81 <h4>Arthur Axel "fREW" Schmidt</h4>
86 <p>You know a little about Perl and using objects</p>
87 <p>You know a little bit about databases and using foreign keys</p>
90 <li>How many people have designed a database with Foreign Keys?</li>
91 <li>How many people have used any ORM?<ul>
94 <li> Class::DBI? </li>
100 <li> DataMapper? </li>
101 <li>(N)Hibernate?</li>
108 <h1>DBIx::Class?</h1>
110 <li>ORM (object relational mapper)</li>
111 <li>SQL <-> OO (using objects instead of SQL)</li>
112 <li>Simple, powerful, complex, fab and confusing</li>
113 <li>There are many ORMs, DBIx::Class just happens to be the best in Perl (personal opinion)</li>
118 <h1>point of note</h1>
119 <p><em>"Debugging is twice as hard as writing the code in the first
120 place. Therefore, if you write the code as cleverly as possible,
121 you are, by definition, not smart enough to debug it." - Brian
122 W. Kernighan</em></p>
124 <p>This talk is about making it easy so we are less likely to get
129 <h1>Examples Table Setup</h1>
134 <em>MySQL not recommended</em>
138 <h1>authors table</h1>
139 <pre>CREATE TABLE authors(
140 id int(8) primary key auto_increment,
142 ) engine = InnoDB DEFAULT CHARSET=utf8;</pre>
147 <p>Name tables as simple plurals (<strong>add an S</strong>) - makes relationships easier to understand</p>
148 <p>Use a character set (<strong>UTF8</strong>) from the start (for international characters)</p>
152 <h1>authors table</h1>
153 <pre>CREATE TABLE author<strong>s</strong>(
154 id int(8) primary key auto_increment,
156 ) engine = <strong>InnoDB</strong> DEFAULT CHARSET=<strong>utf8</strong>;</pre>
161 <pre>CREATE TABLE books(
162 id int(8) primary key auto_increment,
164 author_id int(8),foreign key (author)
165 references authors(id)
166 ) engine = InnoDB DEFAULT CHARSET=utf8;</pre>
172 <p>Name link fields as singular</p>
173 <p>Ensure foreign key is the same type and size in both tables</p>
178 <pre>CREATE TABLE books(
179 id int(8) primary key auto_increment,
181 author_id <strong>int(8)</strong>,<strong>foreign key (<em>author</em>)</strong>
182 <strong>references <em>authors(id)</em></strong>
183 ) engine = InnoDB DEFAULT CHARSET=utf8;</pre>
187 <h1>CRUD compared</h1>
189 <li><strong>C</strong> - Create</li>
190 <li><strong>R</strong> - Read</li>
191 <li><strong>U</strong> - Update</li>
192 <li><strong>D</strong> - Delete</li>
197 <h1>Manual (SQL)</h1>
202 <pre>my $sth = $dbh->prepare('
209 'A book title', $author_id
215 <pre>my $sth = $dbh->prepare('
217 authors.name as author_name
219 WHERE books.author = authors.id
225 <pre>while( my $book = $sth->fetchrow_hashref() ) {
229 . $book->{author_name}
236 <pre>my $update = $dbh->prepare('
243 'New title',<strong>$book_id</strong>
249 <pre>my $delete = $dbh->prepare('
254 $delete->execute(<strong>$book_id</strong>);</pre>
262 <h1>DBIC: Create</h1>
263 <pre>my $book = $book_model->create({
264 title => 'A book title',
265 author => $author_id,
267 <p>Look ma, no SQL!</p>
271 <h1>DBIC: Create</h1>
272 <pre>my $pratchett = $author_model->create({
273 name => 'Terry Pratchett',
278 <h1>DBIC: Create</h1>
279 <pre>my $book = $pratchett->create_related(
280 <strong>books</strong> => {
281 title => 'Another Discworld book',
284 <pre>my $book = $pratchett->add_to_<strong>books</strong>({
285 title => 'Another Discworld book',
291 <p>DBIx::Class - Lots of ways to do the same thing...</p>
292 <p><em>"There is more than one way to do it (TIMTOWTDI, usually pronounced "Tim Toady") is a Perl motto"</em></p>
297 <pre>my $book = $book_model->find($book_id);
299 my $book = $book_model->search({
300 title => 'A book title',
301 }, { rows => 1 })->single;
303 my @books = $book_model->search({
304 author => $author_id,
310 <pre>while( my $book = $books_rs->next ) {
314 . $book->author->name
321 <pre>my $books_rs = $book_rs->search({
322 author => $author_id,
324 <p>Search takes SQL::Abstract formatted queries</p>
325 <pre>> perldoc SQL::Abstract</p>
329 <h1>DBIC: Update</h1>
330 <pre>$book->update({
331 title => 'New title',
336 <h1>DBIC: Delete</h1>
337 <pre>$book->delete;</pre>
341 <h1>Creating models</h1>
345 <pre>package MyApp::Schema::Result::Author;
346 use strict; use warnings;
347 __PACKAGE__->table('authors');
348 __PACKAGE__->add_columns(
350 data_type => 'int',
354 data_type => 'varchar',
359 __PACKAGE__->set_primary_key('id');
360 __PACKAGE__->has_many( books =>
361 'MyApp::Schema::Result::Book', 'author_id'
368 <pre>package MyApp::Schema::Result::Book;
369 use strict; use warnings;
370 __PACKAGE__->table('books');
371 __PACKAGE__->add_columns(
373 data_type => 'int',
377 data_type => 'varchar',
382 data_type => 'int',
384 is_nullable => 1, # <-- probably should be 0
387 __PACKAGE__->set_primary_key('id');
388 __PACKAGE__->belongs_to( author =>
389 'MyApp::Schema::Result::Author', 'author_id'
396 <h1>Schema::Loader</h1>
397 <p>DB -> Perl vs Perl -> DB</p>
398 <pre>package MyApp::Schema;
399 use strict; use warnings;
400 use base 'DBIx::Class::Schema::Loader';
401 __PACKAGE__->loader_options({
403 debug => $ENV{DBIC_TRACE},
409 my $schema = MyApp::Schema->connect($dsn, $user, $pass);
414 <h1>splitting logic cleanly</h1>
415 <p>Foo::Schema::Result::Foo = an individual row</p>
416 <p>Foo::Schema::ResultSet::Foo = searches / results</p>
420 <h1>using your Schema</h1>
421 <pre>example usage code goes here</pre>
426 <pre>DBIC_TRACE=1 ./your_script.pl</pre>
430 <h1>Schema::Loader</h1>
431 <pre>Foo::Schema::Result::Authors->table("authors");
432 Foo::Schema::Result::Authors->add_columns(
434 data_type => "INT",
435 default_value => undef,
440 data_type => "VARCHAR",
441 default_value => undef,
446 Foo::Schema::Result::Authors->set_primary_key("id");</pre>
450 <h1>Schema::Loader</h1>
451 <pre>Foo::Schema::Result::Books->table("books");
452 Foo::Schema::Result::Books->add_columns(
454 data_type => "INT",
455 default_value => undef,
460 data_type => "VARCHAR",
461 default_value => undef,
466 data_type => "INT",
467 default_value => undef,
472 Foo::Schema::Result::Books->set_primary_key("id");</pre>
476 <h1>Schema::Loader</h1>
477 <pre>Foo::Schema::Result::Authors->has_many(books => "Foo::Schema::Books",
478 { "foreign.author" => "self.id" });
480 Foo::Schema::Result::Books->belongs_to(author => "Foo::Schema::Authors",
481 { id => "author" });</pre>
485 <h1>SQL - debugging</h1>
486 <pre>INSERT INTO authors (name)
487 VALUES (?): 'Douglas Adams'
489 INSERT INTO books (author, title)
490 VALUES (?, ?): '5', '42'</pre>
495 <pre>Foo::Schema::Result::Books
496 Foo::Schema::ResultSet::Books
497 Foo::Schema::Result::Authors
498 Foo::Schema::ResultSet::Books</pre>
503 <pre>package Foo::Schema::Result::Books;
504 use base 'DBIx::Class';
511 # search amazon or something
512 my $api = Amazon::API->book({
513 title => $self->title
516 return $api->isbn;
524 <pre>print $book->isbn;</pre>
528 <h1>Result:: (inflating)</h1>
529 <pre>package Foo::Schema::Result::Books;
530 use base 'DBIx::Class';
534 use DateTime::Format::MySQL;
536 __PACKAGE__-><strong>inflate_column</strong>(
537 <strong>date_published</strong> => {
538 inflate => sub { DateTime::Format::MySQL->parse_date(shift) },
539 deflate => sub { shift->ymd},
542 # Automatic see: DBIx::Class::InflateColumn::DateTime</pre>
546 <h1>Result:: (inflating)</h1>
547 <pre>package Foo::Schema::Result::Books;
548 use base 'DBIx::Class';
552 use DateTime::Format::MySQL;
554 __PACKAGE__->inflate_column(
555 date_published => {
556 <strong>inflate => sub { DateTime::Format::MySQL->parse_date(shift) },
557 deflate => sub { shift->ymd},</strong>
560 # Automatic see: DBIx::Class::InflateColumn::DateTime
561 # Automatic see: DBIx::Class::InflateColumn::DateTime
562 # Automatic see: DBIx::Class::InflateColumn::DateTime</pre>
566 <h1>Result:: (deflating)</h1>
567 <pre>$book->date_published(DateTime->now);
568 $book->update;</pre>
572 <h1>Result:: (inflating)</h1>
573 <pre>my $date_published = $book->date_published;
574 print $date_published->month_abbr;</pre>
576 <strong><em>Nov</em></strong>
580 <h1>ResultSets::</h1>
581 <pre>package Foo::Schema::ResultSet::Books;
582 use base 'DBIx::Class::ResultSet';
583 sub the_ultimate_books {
585 return $self->search({ title => { -like => '%42%' } });
588 my ( $self, $author ) = @_;
589 return $self->search({ author => $author->id })
596 <h1>ResultSets::</h1>
597 <pre>package Foo::Schema::<strong>ResultSet::Books</strong>;
598 use base '<strong>DBIx::Class::ResultSet</strong>';
599 sub the_ultimate_books {
601 <strong>return $self->search({ title => { -like => '%42%' } })</strong>
604 my ( $self, $author ) = @_;
605 return $self->search({ author => $author->id })
612 <h1>ResultSets::</h1>
613 <pre>package Foo::Schema::ResultSet::Books;
614 use base 'DBIx::Class::ResultSet';
615 sub the_ultimate_books {
617 return $self->search({ title => { -like => '%42%' } });
620 my ( $self, $author ) = @_;
621 <strong>return $self->search({ author => $author->id })</strong>
628 <h1>ResultSets::</h1>
629 <pre>use Foo::Schema;
630 my $book_model = Foo::Schema->resultset('Books');
631 my $book_rs = $book_model->the_ultimate_books;
632 my @books = $book_rs->all;</pre>
636 <h1>ResultSets::chaining</h1>
637 <pre>use Foo::Schema;
638 my $book_model = Foo::Schema->resultset('Books');
639 my $author_model = Foo::Schema->resultset('Authors');
640 my $author = $author_model->search({ name => 'Douglas Adams' })->single;
641 my $book_rs = $book_model->the_ultimate_books->by_author($author);
642 my @books = $book_rs->all;</pre>
646 <h1>ResultSets::chaining</h1>
647 <pre>my $book_rs = $book_model
648 ->the_ultimate_books
649 ->by_author($author);</pre>
652 <pre>my $book_rs = $book_model
653 ->the_ultimate_books();
654 $book_rs = $book_rs->by_author($author);</pre>
657 # SELECT me.id, me.title, me.date_published, me.author
659 # WHERE ( ( ( author = ? ) AND ( title LIKE ? ) ) ): '5', '%42%'
660 # WHERE ( ( ( author = ? ) AND ( title LIKE ? ) ) ): '5', '%42%'</pre>
664 <h1>ResultSets::chaining</h1>
665 <pre>my $rs = $book_model
666 ->category('childrens')
667 ->by_author($author)
668 ->published_after('1812')
669 ->first_page_contains('once upon')
670 ->rating_greater_than(4);
672 my @books = $rs->all;</pre>
676 <h1>overloading before new record</h1>
680 <h1>overloading before new record</h1>
681 <pre>package Foo::Schema::Result::Authors;
682 use base 'DBIx::Class';
685 my ( $class, $attrs ) = @_;
687 my $new = $class->next::method($attrs);
694 <h1>relationships</h1>
698 <h1>multiple authors</h1>
702 <h1>a few relationships</h1>
703 (authors -- author_link_to_book -- books)
707 <h1>a few relationships</h1>
712 <h1>new join table</h1>
713 <pre>CREATE TABLE author_and_books(
714 id int(8) primary key auto_increment,
717 foreign key (book) references books(id),
718 foreign key (author) references authors(id)
719 ) engine = InnoDB DEFAULT CHARSET=utf8;
721 ALTER TABLE `books` DROP `author`</pre>
725 <h1>new join table</h1>
726 <pre>CREATE TABLE author_and_books(
727 id int(8) primary key auto_increment,
730 <strong>foreign key (book) references books(id),
731 foreign key (author) references authors(id)</strong>
732 ) engine = InnoDB DEFAULT CHARSET=utf8;
734 ALTER TABLE `books` DROP `author`</pre>
743 <pre>package Foo::Schema::<strong>Result::Books</strong>;
745 __PACKAGE__->has_many( author_and_books => "Foo::Schema::Result::AuthorAndBooks",
746 { "foreign.book" => "self.id" },
749 <strong># This is auto generated by Schema::Loader</strong></pre>
754 <pre>package Foo::Schema::<strong>Result::Books</strong>;
756 __PACKAGE__->has_many(
757 author_and_books => <strong># name of accessor</strong>
758 "Foo::Schema::Result::AuthorAndBooks", <strong># related class</strong>
759 { "foreign.book" => "self.id" } <strong># Relationship (magic often works if not
760 # specified, but avoid!)</strong>
771 <pre>package Foo::Schema::<strong>Result::AuthorAndBooks</strong>;
773 __PACKAGE__->belongs_to(
774 book => <strong># Accessor name</strong>
775 "Foo::Schema::Result::Books", <strong># Related class</strong>
776 { id => "book" } <strong># relationship</strong>
782 <h1>same for Authors</h1>
786 <h1>with no coding...</h1>
790 <h1>many_to_many</h1>
794 <h1>many_to_many</h1>
795 <pre>package Foo::Schema::<strong>Result::Books</strong>;
796 use base 'DBIx::Class';
798 __PACKAGE__->many_to_many(
799 authors => "author_and_books", 'author'
804 <strong> # This is <em>NOT</em> auto generated by Schema::Loader </strong></pre>
808 <h1>many_to_many</h1>
809 <pre>package Foo::Schema::<strong>Result::Books</strong>;
810 use base 'DBIx::Class';
812 __PACKAGE__->many_to_many(
813 authors <strong># Accessor name</strong>
814 => "author_and_books", <strong># has_many</strong>
815 'author' <strong># foreign relationship name</strong>
822 <h1>many_to_many</h1>
823 <pre>package Foo::Schema::Result::Authors;
824 use base 'DBIx::Class';
826 __PACKAGE__->many_to_many(
827 "books" <strong># Accessor Name</strong>
828 => "author_and_books", <strong># has_many accessor_name</strong>
829 'book' <strong># foreign relationship name</strong>
834 <strong># This is <em>NOT</em> auto generated by Schema::Loader</strong></pre>
838 <h1>using many_to_many</h1>
843 my $author_model = Foo::Schema->resultset('Authors');
844 my $author = $author_model->search({
845 name => 'Douglas Adams',
847 $author->add_to_books({
848 title => 'A new book',
853 <h1>using many_to_many</h1>
854 <pre>my $author = $author_model->search({
855 name => 'Douglas Adams',
857 <strong>$author->add_to_books({
858 title => 'A new book',
861 # SELECT me.id, me.name FROM authors me
862 # WHERE ( name = ? ): 'Douglas Adams';
863 # INSERT INTO books (title) VALUES (?): 'A new book';
864 # INSERT INTO author_and_books (author, book)
865 # VALUES (?, ?): '5', '2';</pre>
869 <h1>using many_to_many</h1>
870 <pre>$author->add_to_books($book);
872 $book->add_to_authors($author_1);
873 $book->add_to_authors($author_2);</pre>
877 <h1>in 16 lines of code</h1>
882 <p>Read them closely!</p>
886 <h1>error messages</h1>
887 <pre>DBIx::Class::Schema::Loader::connection(): Failed to load external class definition for 'Foo::Schema::Result::Authors': Can't locate object method "many_to_many" via package "Foo::Schema::Result::Author" at lib/Foo/Schema/Result/Authors.pm line 9.Compilation failed in require at /Library/Perl/5.8.8/DBIx/Class/Schema/Loader/Base.pm line 292.</pre>
891 <h1>error messages</h1>
892 <pre>DBIx::Class::Schema::Loader::connection(): Failed to load external class definition for 'Foo::Schema::Result::Authors': Can't locate object method "many_to_many" via package "Foo::Schema::<strong>Result::Author</strong>" at lib/Foo/Schema/<strong>Result/Authors.pm</strong> line 9.Compilation failed in require at /Library/Perl/5.8.8/DBIx/Class/Schema/Loader/Base.pm line 292.</pre>
898 <li>Turn on debugging</li>
899 <li>Read error messages (sometimes useful!)</li>
900 <li>Check field names</li>
901 <li>Check package names</li>
902 <li>Check which database you are connected to (dev/test/live?) - repeat above</li>
907 <h1>bonus slides!</h1>
911 <h1>Template Toolkit</h1>
913 <li><pre>[% author.books.count %]</pre> not working?</li>
914 <li>TT all methods are called in list context</li>
915 <li><pre>[% author.books<strong>_rs</strong>.count %]</pre> scalar context</li>
916 <li><em>Available for all relationships</em></li>
922 <pre>package Your::App::Model::<strong>Foo</strong>;
923 use base qw(<strong>Catalyst::Model::Schema::Schema</strong>);
928 __PACKAGE__->config(
929 schema_class => '<strong>Foo::Schema</strong>',
933 <p>Keep your Schema in a <em>separate</em> package to your Catalyst application</p>
938 <pre>sub action_name : Local {
941 my $model = $c->model('Schema::Foo');
942 my $author_model = $model->resultset('Authors');