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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>Amiri Barksdale</h4>
80 <h4>Justin D. Hunter</h4>
81 <h4>Arthur Axel "fREW" Schmidt</h4>
85 <h1>What's up guys?</h1>
88 <li>How many people have used any ORM?<ul>
98 <li>(N)Hibernate?</li>
106 <p>The purpose of this talk is to show you as many features of
107 DBIx::Class in 40 minutes so that when you need to do something with
108 it later you will know what's possible</p>
112 <h1>DBIx::Class?</h1>
114 <li>ORM (object relational mapper)</li>
115 <li>SQL <-> OO (using objects instead of SQL)</li>
116 <li>There are many ORMs, DBIx::Class just happens to be the best in Perl (personal opinion)</li>
122 <p>These are reasons that are not technical or inherent to
123 the code of DBIC, but are totally awesome things about it.</p>
127 <h1>Large Community</h1>
128 <p>Currently there are 88 people listed as contributors to DBIC. That
129 ranges from documentation help, to test help, to added features,
130 to entire database support.</p>
134 <h1>Active Community</h1>
135 <p>Currently (June 9, 2010) 6 active branches (commited to in the last two weeks) in git. Last release (0.08122) had 14 new features, and 16 bug fixes. Of course that <a href="http://git.shadowcat.co.uk/gitweb/gitweb.cgi?p=dbsrgits/DBIx-Class.git;a=blob;f=Changes">ebbs and flows</a>.</p>
139 <h1>Responsive Community</h1>
140 <ul class="incremental">
141 <li>needed MSSQL Order by support, they helped me add support</li>
142 <li>generally very welcoming of people willing to help</li>
148 <p>These are things that are in most other ORMs, but are still reasons
149 to use DBIC over raw SQL.</p>
154 <p>The vast majority of code should run on all databases without needing tweaking</p>
159 <ul class="incremental">
160 <li><strong>C</strong> - Create</li>
161 <li><strong>R</strong> - Read</li>
162 <li><strong>U</strong> - Update</li>
163 <li><strong>D</strong> - Delete</li>
169 <pre>my $sth = $dbh->prepare('
176 'A book title', $author_id
181 <h1>DBIC: Create</h1>
182 <pre>my $book = $book_rs->create({
183 title => 'A book title',
184 author_id => $author_id,
186 <ul class="incremental">
187 <li>No need to pair placeholders and values</li>
188 <li>Automatically gets autoincremented id for you</li>
189 <li>Transparrently uses INSERT ... RETURNING for databases that support it</li>
195 <pre>my $sth = $dbh->prepare('
197 authors.name as author_name
199 WHERE books.author = authors.id
205 <pre>while( my $book = $sth->fetchrow_hashref() ) {
209 . $book->{author_name}
216 <pre>my $book = $book_rs->find($book_id);
218 my $book = $book_rs->search({
219 title => 'A book title',
220 }, { rows => 1 })->next;
222 my @books = $book_rs->search({
223 author => $author_id,
225 <ul class="incremental">
232 <pre>while( my $book = $books_rs->next ) {
236 . $book->author->name
243 <pre>my $update = $dbh->prepare('
250 'New title',<strong>$book_id</strong>
255 <h1>DBIC: Update</h1>
256 <pre>$book->update({
257 title => 'New title',
259 <ul class="incremental">
266 <pre>my $delete = $dbh->prepare('
271 $delete->execute(<strong>$book_id</strong>);</pre>
275 <h1>DBIC: Delete</h1>
276 <pre>$book->delete;</pre>
280 <h1>OO Overidability</h1>
281 <ul class="incremental">
282 <li>Override new if you want to do validation</li>
283 <li>Override delete if you want to disable deletion</li>
284 <li>and on and on</li>
287 <p>I got yelled at about this before by people, so
288 we don't get EVERYTHING from OO, but we do get a lot
294 <h1>Convenience Methods</h1>
295 <ul class="incremental">
296 <li>find_or_create</li>
297 <li>create_or_update</li>
302 <h1>Non-column methods</h1>
303 <p>Need a method to get a user's gravatar URL? Add a
304 gravatar_url method to their Result class</p>
308 <h1>RELATIONSHIPS</h1>
309 <ul class="incremental">
310 <li><a href="http://search.cpan.org/perldoc?DBIx::Class::Relationship#belongs_to">belongs_to</a></li>
311 <li><a href="http://search.cpan.org/perldoc?DBIx::Class::Relationship#has_many">has_many</a></li>
312 <li><a href="http://search.cpan.org/perldoc?DBIx::Class::Relationship#might_have">might_have</a></li>
313 <li><a href="http://search.cpan.org/perldoc?DBIx::Class::Relationship#has_one">has_one</a></li>
314 <li><a href="http://search.cpan.org/perldoc?DBIx::Class::Relationship#many_to_many">many_to_many</a> (technically not a relationship)</li>
315 <li>SET AND FORGET</li>
320 <h1>DBIx::Class Specific Features</h1>
321 <p>These things may be in other ORM's, but they are very specific, so doubtful</p>
327 <pre>my $schema = Foo::Schema->connect(
332 <p>See also: <a href="http://search.cpan.org/perldoc?DBIx::Class::DeploymentHandler">DBIx::Class::DeploymentHandler</a></p>
336 <h1>Schema::Loader</h1>
338 <pre>package Foo::Schema;
339 use strict; use warnings;
340 use base 'DBIx::Class::Schema::Loader';
341 __PACKAGE__->loader_options({
343 debug => $ENV{DBIC_TRACE},
349 my $schema = Foo::Schema->connect(
357 <p>Made for inserting lots of rows very quicky into database</p>
358 <pre>$schema->populate([ Users =>
359 [qw( username password )],
360 [qw( frew >=4char$ )],
365 <ul class="incremental">
366 <li>I use this to <a href="http://blog.afoolishmanifesto.com/archives/1255">export our whole (200M~) db to SQLite</a></li>
372 <p>Create an object and all of it's related objects all at once</p>
373 <pre>$schema->resultset('Author')->create({
374 name => 'Stephen King',
375 books => [{ title => 'The Dark Tower' }],
377 street => '123 Turtle Back Lane',
378 state => { abbreviation => 'ME' },
379 city => { name => 'Lowell' },
385 <li>books is a has_many</li>
386 <li>address is a belongs_to which in turn belongs to state and city each</li>
387 <li>for this to work right state and city must mark abbreviation and name as unique</li>
394 <p>DBIx::Class helped pioneer fast MI in Perl 5 with Class::C3, so it is made
395 to allow extensions to nearly every part of it.</p>
399 <h1>Extensible: DBIC::Helpers</h1>
400 <ul class="incremental">
401 <li>DBIC::Helper::ResultSet::IgnoreWantarray</li>
402 <li>DBIC::Helper::ResultSet::Random</li>
403 <li>DBIC::Helper::ResultSet::SetOperations</li>
404 <li>DBIC::Helper::Row::JoinTable</li>
405 <li>DBIC::Helper::Row::NumifyGet</li>
406 <li>DBIC::Helper::Row::SubClass</li>
407 <li>DBIC::Helper::Row::ToJSON</li>
412 <h1>Extensible: DBIC::TimeStamp</h1>
413 <ul class="incremental">
415 <li>set_on_create</li>
416 <li>set_on_update</li>
421 <h1>Extensible: Kioku</h1>
422 <ul class="incremental">
423 <li>DBIx::Class::Schema::KiokuDB</li>
424 <li>Kioku is the new hotness</li>
425 <li>Mix RDBMS with Object DB</li>
426 <li>beta ( == sexy )</li>
431 <h1>SQL::Abstract</h1>
432 <pre>my $resultset = $book_rs->search({
433 name => { -like => "%$nick%" },
435 <ul class="incremental">
436 <li>(kinda) introspectible</li>
437 <li>Prettier than SQL</li>
442 <h1>Result vs ResultSet</h1>
443 <ul class="incremental">
444 <li>Result == Row</li>
445 <li>ResultSet == Query Plan<ul class="incremental">
446 <li>Internal Join Optimizer for all DB's (!!!)</li>
448 <li>(less important but...)</li>
449 <li>ResultSource == Table</li>
450 <li>Storage == Database</li>
455 <h1>ResultSet methods</h1>
456 <pre>package MyApp::Schema::ResultSet::Book;
457 use base 'DBIx::Class::ResultSet';
461 $self->current_source_alias .
462 '.rating' => { '>=' => 4 },
468 $self->current_source_alias .
469 '.price' => { '<=' => 5}
478 <h1>ResultSet method notes</h1>
479 <ul class="incremental">
480 <li>All searches should be ResultSet methods</li>
481 <li>Name has obvious meaning</li>
482 <li>current_source_alias helps things to work no matter what</li>
487 <h1>ResultSet method in Action</h1>
488 <pre>$schema->resultset('Book')->good</pre>
492 <h1>ResultSet Chaining</h1>
493 <pre>$schema->resultset('Book')
501 <h1>search_related</h1>
502 <pre>my $score = $schema->resultset('User')
503 ->search({'me.userid' => 'frew'})
504 ->related_resultset('access')
505 ->related_resultset('mgmt')
506 ->related_resultset('orders')
508 ->search_related( shops => {
509 'shops.datecompleted' => {
510 -between => ['2009-10-01','2009-10-08']
513 ->related_resultset('rpt_score')
514 ->get_column('raw_scores')
520 <h1>bonus rel methods</h1>
521 <pre>my $book = $author->create_related(
522 <strong>books</strong> => {
523 title => 'Another Discworld book',
527 my $book2 = $pratchett->add_to_<strong>books</strong>({
528 title => 'MOAR Discworld book',
530 <ul class="incremental">
531 <li>Automaticaly fills in foreign key for you</li>
536 <h1>Excellent Transaction Support</h1>
537 <pre>$schema->txn_do(sub {
541 my $guard = $schema->txn_scope_guard;
545 $schema->txn_begin; # <-- low level
547 $schema->txn_commit;
552 <h1>InflateColumn</h1>
553 <pre>package Foo::Schema::Result::Book;
554 use base 'DBIx::Class::Core';
555 use DateTime::Format::MySQL;
557 __PACKAGE__->load_components('InflateColumn');
558 __PACKAGE__-><strong>inflate_column</strong>(
559 <strong>date_published</strong> => {
561 DateTime::Format::MySQL->parse_date(
565 deflate => sub { shift->ymd },
568 # Automatic see: DBIC::InflateColumn::DateTime</pre>
572 <h1>InflateColumn: deflation</h1>
573 <pre>$book->date_published(DateTime->now);
574 $book->update;</pre>
578 <h1>InflateColumn: inflation</h1>
579 <pre>say $book->date_published->month_abbr;</pre>
581 <strong><em>Nov</em></strong>
585 <h1>FilterColumn</h1>
586 <pre>package Foo::Schema::Result::Book;
587 use base 'DBIx::Class::Core';
589 __PACKAGE__->load_components('FilterColumn');
591 __PACKAGE__-><strong>filter_column</strong>(
592 <strong>length</strong> => {
593 to_storage => 'to_metric',
594 from_storage => 'to_imperial',
598 sub to_metric { $_[1] * .305 }
599 sub to_imperial { $_[1] * 3.28 }
603 <h1>ResultSetColumn</h1>
604 <pre>my $rsc = $schema->resultset('Book')
605 ->get_column('price');
614 <pre>my @res = $rs->search({}, {
622 qw(price genre max_price avg_price)
624 group_by => [qw(price genre)],
627 say $_->price . ' ' . $_->genre;
628 say $_->get_column('max_price');
629 say $_->get_column('min_price');
634 <h1>Aggregates Notes</h1>
635 <ul class="incremental">
636 <li>Careful, get_column can basicaly mean THREE things</li>
637 <li>private for get what you should use an accessor for</li>
638 <li>public for what there is no accessor for</li>
639 <li>public for get resultset column (prev slide)</li>
645 <pre>$rs->search({}, {
647 'DBIx::Class::ResultClass::HashRefInflator',
649 <ul class="incremental">
650 <li>Easy on memory</li>
652 <li>Great for quick debugging</li>
653 <li>Great for performance tuning (we went from 2m to < 3s)</li>
658 <h1>Subquery Support</h1>
659 <pre>my $inside_query = $schema->resultset('Artist')
661 name => [ 'Billy Joel', 'Brittany Spears' ],
662 })->get_column('id')->as_query;
664 my $rs = $schema->resultset('CD')->search({
665 artist_id => { -in => $inside_query },
670 <h1>Bare SQL w/ Placeholders</h1>
671 <pre>$rs->update({
672 # !!! SQL INJECTION VECTOR
673 price => \"price + $inc",
677 price => \['price + ?', [inc => $inc]],