Commit | Line | Data |
876f6525 |
1 | package DBIx::Class::ResultSource::MultipleTableInheritance; |
2 | |
3 | use strict; |
4 | use warnings; |
5 | use parent qw(DBIx::Class::ResultSource::View); |
876f6525 |
6 | use Method::Signatures::Simple; |
7 | use Carp::Clan qw/^DBIx::Class/; |
ca79850d |
8 | use aliased 'DBIx::Class::ResultSource::Table'; |
7abe3af2 |
9 | use aliased 'DBIx::Class::ResultClass::HashRefInflator'; |
05fd2477 |
10 | use String::TT qw(strip tt); |
92ebfc06 |
11 | use Scalar::Util qw(blessed); |
ca79850d |
12 | use namespace::autoclean; |
70d56286 |
13 | |
146ec120 |
14 | our $VERSION = 0.01; |
70d56286 |
15 | |
803ffff2 |
16 | __PACKAGE__->mk_group_accessors(simple => qw(parent_source additional_parents)); |
876f6525 |
17 | |
e7189506 |
18 | # how this works: |
19 | # |
20 | # On construction, we hook $self->result_class->result_source_instance |
21 | # if present to get the superclass' source object |
5fa55fff |
22 | # |
e7189506 |
23 | # When attached to a schema, we need to add sources to that schema with |
24 | # appropriate relationships for the foreign keys so the concrete tables |
25 | # get generated |
26 | # |
27 | # We also generate our own view definition using this class' concrete table |
28 | # and the view for the superclass, and stored procedures for the insert, |
29 | # update and delete operations on this view. |
30 | # |
31 | # deploying the postgres rules through SQLT may be a pain though. |
32 | |
876f6525 |
33 | method new ($class: @args) { |
34 | my $new = $class->next::method(@args); |
35 | my $rc = $new->result_class; |
36 | if (my $meth = $rc->can('result_source_instance')) { |
7abe3af2 |
37 | my $source = $rc->$meth; |
38 | if ($source->result_class ne $new->result_class |
39 | && $new->result_class->isa($source->result_class)) { |
40 | $new->parent_source($source); |
41 | } |
876f6525 |
42 | } |
43 | return $new; |
44 | } |
45 | |
4e4f71e3 |
46 | method add_additional_parents (@classes) { |
47 | foreach my $class (@classes) { |
48 | Class::C3::Componentised->ensure_class_loaded($class); |
49 | $self->add_additional_parent( |
50 | $class->result_source_instance |
51 | ); |
52 | } |
53 | } |
54 | |
803ffff2 |
55 | method add_additional_parent ($source) { |
56 | my ($our_pk, $their_pk) = map { |
57 | join('|',sort $_->primary_columns) |
58 | } ($self, $source); |
59 | |
60 | confess "Can't attach additional parent ${\$source->name} - it has different PKs ($their_pk versus our $our_pk)" |
61 | unless $their_pk eq $our_pk; |
62 | $self->additional_parents([ |
63 | @{$self->additional_parents||[]}, $source |
64 | ]); |
65 | $self->add_columns( |
66 | map { |
67 | $_ => # put the extra key first to default it |
68 | { originally_defined_in => $source->name, %{$source->column_info($_)}, }, |
69 | } grep !$self->has_column($_), $source->columns |
70 | ); |
71 | foreach my $rel ($source->relationships) { |
72 | my $rel_info = $source->relationship_info($rel); |
73 | $self->add_relationship( |
74 | $rel, $rel_info->{source}, $rel_info->{cond}, |
75 | # extra key first to default it |
76 | {originally_defined_in => $source->name, %{$rel_info->{attrs}}}, |
77 | ); |
78 | } |
a010ebf9 |
79 | { no strict 'refs'; |
80 | push(@{$self->result_class.'::ISA'}, $source->result_class); |
81 | } |
803ffff2 |
82 | } |
83 | |
8b229aa6 |
84 | method _source_by_name ($name) { |
85 | my $schema = $self->schema; |
5fa55fff |
86 | my ($source) = |
8b229aa6 |
87 | grep { $_->name eq $name } |
88 | map $schema->source($_), $schema->sources; |
89 | confess "Couldn't find attached source for parent $name - did you use load_classes? This module is only compatible with load_namespaces" |
90 | unless $source; |
91 | return $source; |
92 | } |
93 | |
7abe3af2 |
94 | method schema (@args) { |
95 | my $ret = $self->next::method(@args); |
96 | if (@args) { |
c73d582b |
97 | if ($self->parent_source) { |
c73d582b |
98 | my $parent_name = $self->parent_source->name; |
8b229aa6 |
99 | $self->parent_source($self->_source_by_name($parent_name)); |
c73d582b |
100 | } |
8b229aa6 |
101 | $self->additional_parents([ |
102 | map { $self->_source_by_name($_->name) } |
103 | @{$self->additional_parents||[]} |
104 | ]); |
7abe3af2 |
105 | } |
106 | return $ret; |
107 | } |
108 | |
c73d582b |
109 | method attach_additional_sources () { |
4d88a8d7 |
110 | my $raw_name = $self->raw_source_name; |
ca79850d |
111 | my $schema = $self->schema; |
112 | |
113 | # if the raw source is already present we can assume we're done |
114 | return if grep { $_ eq $raw_name } $schema->sources; |
4d88a8d7 |
115 | |
ca79850d |
116 | # our parent should've been registered already actually due to DBIC |
117 | # attaching subclass sources later in load_namespaces |
4d88a8d7 |
118 | |
ca79850d |
119 | my $parent; |
120 | if ($self->parent_source) { |
121 | my $parent_name = $self->parent_source->name; |
5fa55fff |
122 | ($parent) = |
ca79850d |
123 | grep { $_->name eq $parent_name } |
124 | map $schema->source($_), $schema->sources; |
125 | confess "Couldn't find attached source for parent $parent_name - did you use load_classes? This module is only compatible with load_namespaces" |
126 | unless $parent; |
05fd2477 |
127 | $self->parent_source($parent); # so our parent is the one in this schema |
ca79850d |
128 | } |
4d88a8d7 |
129 | |
130 | # create the raw table source |
131 | |
132 | my $table = Table->new({ name => $self->raw_table_name }); |
133 | |
ca79850d |
134 | # we don't need to add the PK cols explicitly if we're the root table |
4d88a8d7 |
135 | # since they'll get added below |
136 | |
803ffff2 |
137 | my %pk_join; |
138 | |
ca79850d |
139 | if ($parent) { |
ca79850d |
140 | foreach my $pri ($self->primary_columns) { |
141 | my %info = %{$self->column_info($pri)}; |
142 | delete @info{qw(is_auto_increment sequence auto_nextval)}; |
7abe3af2 |
143 | $table->add_column($pri => \%info); |
803ffff2 |
144 | $pk_join{"foreign.${pri}"} = "self.${pri}"; |
ca79850d |
145 | } |
4d88a8d7 |
146 | # have to use source name lookups rather than result class here |
147 | # because we don't actually have a result class on the raw sources |
803ffff2 |
148 | $table->add_relationship('parent', $parent->raw_source_name, \%pk_join); |
c8e085ba |
149 | $self->deploy_depends_on->{$parent->result_class} = 1; |
803ffff2 |
150 | } |
151 | |
152 | foreach my $add (@{$self->additional_parents||[]}) { |
153 | $table->add_relationship( |
154 | 'parent_'.$add->name, $add->source_name, \%pk_join |
155 | ); |
c965b761 |
156 | $self->deploy_depends_on->{$add->result_class} = 1 if $add->isa('DBIx::Class::ResultSource::View'); |
ca79850d |
157 | } |
4d88a8d7 |
158 | $table->add_columns( |
159 | map { ($_ => { %{$self->column_info($_)} }) } |
160 | grep { $self->column_info($_)->{originally_defined_in} eq $self->name } |
161 | $self->columns |
162 | ); |
ca79850d |
163 | $table->set_primary_key($self->primary_columns); |
5fa55fff |
164 | |
490d5481 |
165 | # we need to copy our rels to the raw object as well |
166 | # note that ->add_relationship on a source object doesn't create an |
167 | # accessor so we can leave that part in the attributes |
168 | |
169 | # if the other side is a table then we need to copy any rels it has |
170 | # back to us, as well, so that they point at the raw table. if the |
171 | # other side is an MTI view then we need to create the rels to it to |
172 | # point at -its- raw table; we don't need to worry about backrels because |
173 | # it's going to run this method too (and its raw source might not exist |
174 | # yet so we can't, anyway) |
175 | |
176 | foreach my $rel ($self->relationships) { |
177 | my $rel_info = $self->relationship_info($rel); |
178 | |
803ffff2 |
179 | # if we got this from the superclass, -its- raw table will nail this. |
180 | # if we got it from an additional parent, it's its problem. |
181 | next unless $rel_info->{attrs}{originally_defined_in} eq $self->name; |
182 | |
490d5481 |
183 | my $f_source = $schema->source($rel_info->{source}); |
184 | |
185 | # __PACKAGE__ is correct here because subclasses should be caught |
186 | |
187 | my $one_of_us = $f_source->isa(__PACKAGE__); |
188 | |
189 | my $f_source_name = $f_source->${\ |
190 | ($one_of_us ? 'raw_source_name' : 'source_name') |
191 | }; |
5fa55fff |
192 | |
490d5481 |
193 | $table->add_relationship( |
194 | '_'.$rel, $f_source_name, @{$rel_info}{qw(cond attrs)} |
195 | ); |
196 | |
197 | unless ($one_of_us) { |
198 | my $reverse = do { |
199 | # we haven't been registered yet, so reverse_ cries |
200 | # XXX this is evil and will probably break eventually |
201 | local @{$schema->source_registrations} |
202 | {map $self->$_, qw(source_name result_class)} |
203 | = ($self, $self); |
204 | $self->reverse_relationship_info($rel); |
205 | }; |
206 | foreach my $rev_rel (keys %$reverse) { |
207 | $f_source->add_relationship( |
208 | '_raw_'.$rev_rel, $raw_name, @{$reverse->{$rev_rel}}{qw(cond attrs)} |
209 | ); |
210 | } |
211 | } |
212 | } |
213 | |
ca79850d |
214 | $schema->register_source($raw_name => $table); |
215 | } |
216 | |
217 | method set_primary_key (@args) { |
218 | if ($self->parent_source) { |
219 | confess "Can't set primary key on a subclass"; |
220 | } |
221 | return $self->next::method(@args); |
876f6525 |
222 | } |
223 | |
e96b2eeb |
224 | method set_sequence ($table_name, @pks) { |
225 | return $table_name . '_' . join('_',@pks) . '_' . 'seq'; |
226 | } |
227 | |
4d88a8d7 |
228 | method raw_source_name () { |
876f6525 |
229 | my $base = $self->source_name; |
05fd2477 |
230 | confess "Can't generate raw source name for ${\$self->name} when we don't have a source_name" |
876f6525 |
231 | unless $base; |
232 | return 'Raw::'.$base; |
233 | } |
70d56286 |
234 | |
4d88a8d7 |
235 | method raw_table_name () { |
236 | return '_'.$self->name; |
237 | } |
238 | |
876f6525 |
239 | method add_columns (@args) { |
240 | my $ret = $self->next::method(@args); |
241 | $_->{originally_defined_in} ||= $self->name for values %{$self->_columns}; |
242 | return $ret; |
70d56286 |
243 | } |
244 | |
803ffff2 |
245 | method add_relationship ($name, $f_source, $cond, $attrs) { |
246 | $self->next::method( |
247 | $name, $f_source, $cond, |
248 | { originally_defined_in => $self->name, %{$attrs||{}}, } |
249 | ); |
250 | } |
251 | |
487f4489 |
252 | BEGIN { |
253 | |
459cd98b |
254 | sub argify { |
255 | my @names = @_; |
256 | map '_' . $_, @names; |
257 | } |
487f4489 |
258 | |
459cd98b |
259 | sub qualify_with { |
260 | my $source = shift; |
261 | my @names = @_; |
262 | my $name = blessed($source) ? $source->name : $source; |
263 | map join( '.', $name, $_ ), @names; |
264 | } |
487f4489 |
265 | |
459cd98b |
266 | sub body_cols { |
267 | my $source = shift; |
268 | my %pk; |
269 | @pk{ $source->primary_columns } = (); |
270 | map +{ %{ $source->column_info($_) }, name => $_ }, |
487f4489 |
271 | grep !exists $pk{$_}, $source->columns; |
459cd98b |
272 | } |
487f4489 |
273 | |
459cd98b |
274 | sub pk_cols { |
275 | my $source = shift; |
276 | map +{ %{ $source->column_info($_) }, name => $_ }, |
487f4489 |
277 | $source->primary_columns; |
459cd98b |
278 | } |
487f4489 |
279 | |
459cd98b |
280 | sub names_of { my @cols = @_; map $_->{name}, @cols } |
487f4489 |
281 | |
459cd98b |
282 | sub function_body { |
283 | my ( $name, $args, $body_parts ) = @_; |
284 | my $arglist = |
285 | join( ', ', map "_${\$_->{name}} ${\uc($_->{data_type})}", @$args ); |
286 | my $body = join( "\n", '', map " $_;", @$body_parts ); |
05fd2477 |
287 | return strip tt q{ |
288 | CREATE OR REPLACE FUNCTION [% name %] |
289 | ([% arglist %]) |
290 | RETURNS VOID AS $function$ |
291 | BEGIN |
292 | [%- body %] |
293 | END; |
294 | $function$ LANGUAGE plpgsql; |
295 | }; |
459cd98b |
296 | } |
487f4489 |
297 | } |
298 | |
05fd2477 |
299 | BEGIN { |
300 | |
459cd98b |
301 | sub arg_hash { |
302 | my $source = shift; |
303 | map +( $_ => \( argify $_) ), names_of body_cols $source; |
304 | } |
92ebfc06 |
305 | |
459cd98b |
306 | sub rule_body { |
307 | my ( $on, $to, $oldlist, $newlist ) = @_; |
308 | my $arglist = join( ', ', |
309 | ( qualify_with 'OLD', names_of @$oldlist ), |
310 | ( qualify_with 'NEW', names_of @$newlist ), |
92ebfc06 |
311 | ); |
312 | $to = $to->name if blessed($to); |
313 | return strip tt q{ |
314 | CREATE RULE _[% to %]_[% on %]_rule AS |
315 | ON [% on | upper %] TO [% to %] |
316 | DO INSTEAD ( |
3c259cfb |
317 | SELECT [% to %]_[% on %]([% arglist %]) |
92ebfc06 |
318 | ); |
319 | }; |
459cd98b |
320 | } |
05fd2477 |
321 | } |
322 | |
323 | method root_table () { |
324 | $self->parent_source |
325 | ? $self->parent_source->root_table |
326 | : $self->schema->source($self->raw_source_name) |
327 | } |
328 | |
487f4489 |
329 | method view_definition () { |
330 | my $schema = $self->schema; |
331 | confess "Can't generate view without connected schema, sorry" |
332 | unless $schema && $schema->storage; |
333 | my $sqla = $schema->storage->sql_maker; |
2816c8ed |
334 | my $table = $self->schema->source($self->raw_source_name); |
487f4489 |
335 | my $super_view = $self->parent_source; |
2816c8ed |
336 | my @all_parents = my @other_parents = @{$self->additional_parents||[]}; |
337 | push(@all_parents, $super_view) if defined($super_view); |
338 | my @sources = ($table, @all_parents); |
487f4489 |
339 | my @body_cols = map body_cols($_), @sources; |
d8c2caa7 |
340 | |
341 | # Order body_cols to match the columns order. |
342 | # Must match or you get typecast errors. |
343 | my %body_cols = map { $_->{name} => $_ } @body_cols; |
344 | @body_cols = |
345 | map { $body_cols{$_} } |
346 | grep { defined $body_cols{$_} } |
347 | $self->columns; |
487f4489 |
348 | my @pk_cols = pk_cols $self; |
92ebfc06 |
349 | |
d8c2caa7 |
350 | # Grab sequence from root table. Only works with one PK named id... |
f49b3ff1 |
351 | # TBD: Fix this so it's more flexible. |
d8c2caa7 |
352 | for my $pk_col (@pk_cols) { |
353 | $self->columns_info->{ $pk_col->{name} }->{sequence} = |
354 | $self->root_table->name . '_id_seq'; |
355 | } |
356 | |
92ebfc06 |
357 | # SELECT statement |
358 | |
2816c8ed |
359 | my $am_root = !($super_view || @other_parents); |
360 | |
487f4489 |
361 | my $select = $sqla->select( |
2816c8ed |
362 | ($am_root |
363 | ? ($table->name) |
364 | : ([ # FROM _tbl _tbl |
487f4489 |
365 | { $table->name => $table->name }, |
2816c8ed |
366 | map { |
367 | my $parent = $_; |
368 | [ # JOIN view view |
369 | { $parent->name => $parent->name }, |
370 | # ON _tbl.id = view.id |
371 | { map +(qualify_with($parent, $_), qualify_with($table, $_)), |
372 | names_of @pk_cols } |
373 | ] |
374 | } @all_parents |
487f4489 |
375 | ]) |
2816c8ed |
376 | ), |
487f4489 |
377 | [ (qualify_with $table, names_of @pk_cols), names_of @body_cols ], |
05fd2477 |
378 | ).';'; |
92ebfc06 |
379 | |
2816c8ed |
380 | my ($now, @next) = grep defined, $super_view, $table, @other_parents; |
92ebfc06 |
381 | |
382 | # INSERT function |
383 | |
05fd2477 |
384 | # NOTE: this assumes a single PK col called id with a sequence somewhere |
385 | # but nothing else -should- so fixing this should make everything work |
386 | my $insert_func = |
c8e085ba |
387 | function_body |
05fd2477 |
388 | $self->name.'_insert', |
389 | \@body_cols, |
390 | [ |
2816c8ed |
391 | $sqla->insert( # INSERT INTO tbl/super_view (foo, ...) VALUES (_foo, ...) |
05fd2477 |
392 | $now->name, |
393 | { arg_hash $now }, |
394 | ), |
2816c8ed |
395 | (map { |
396 | $sqla->insert( # INSERT INTO parent (id, ...) |
397 | # VALUES (currval('_root_tbl_id_seq'), ...) |
398 | $_->name, |
399 | { |
400 | (arg_hash $_), |
401 | id => \"currval('${\$self->root_table->name}_id_seq')", |
402 | } |
403 | ) |
404 | } @next) |
05fd2477 |
405 | ]; |
92ebfc06 |
406 | |
05fd2477 |
407 | # note - similar to arg_hash but not quite enough to share code sanely |
408 | my $pk_where = { # id = _id AND id2 = _id2 ... |
409 | map +($_ => \"= ${\argify $_}"), names_of @pk_cols |
410 | }; |
92ebfc06 |
411 | |
412 | # UPDATE function |
413 | |
05fd2477 |
414 | my $update_func = |
c8e085ba |
415 | function_body |
05fd2477 |
416 | $self->name.'_update', |
417 | [ @pk_cols, @body_cols ], |
418 | [ map $sqla->update( |
419 | $_->name, # UPDATE foo |
420 | { arg_hash $_ }, # SET a = _a |
421 | $pk_where, |
422 | ), @sources |
423 | ]; |
92ebfc06 |
424 | |
425 | # DELETE function |
426 | |
05fd2477 |
427 | my $delete_func = |
c8e085ba |
428 | function_body |
05fd2477 |
429 | $self->name.'_delete', |
430 | [ @pk_cols ], |
431 | [ map $sqla->delete($_->name, $pk_where), @sources ]; |
92ebfc06 |
432 | |
433 | my @rules = ( |
434 | (rule_body insert => $self, [], \@body_cols), |
435 | (rule_body update => $self, \@pk_cols, \@body_cols), |
436 | (rule_body delete => $self, \@pk_cols, []), |
437 | ); |
438 | return join("\n\n", $select, $insert_func, $update_func, $delete_func, @rules); |
487f4489 |
439 | } |
440 | |
70d56286 |
441 | 1; |
146ec120 |
442 | |
443 | __END__ |
f5c54951 |
444 | |
146ec120 |
445 | =head1 NAME |
446 | |
f5c54951 |
447 | DBIx::Class::ResultSource::MultipleTableInheritance |
5fa55fff |
448 | Use multiple tables to define your classes |
f5c54951 |
449 | |
450 | =head1 NOTICE |
451 | |
f49b3ff1 |
452 | This only works with PostgreSQL at the moment. It has been tested with |
453 | PostgreSQL 9.0 and 9.1 beta. |
454 | |
455 | There is one additional caveat: the "parent" result classes that you |
456 | defined with this resultsource must have one primary column and it must |
457 | be named "id." |
146ec120 |
458 | |
459 | =head1 SYNOPSIS |
460 | |
146ec120 |
461 | { |
f8864134 |
462 | package Cafe::Result::Coffee; |
146ec120 |
463 | |
f8864134 |
464 | use strict; |
465 | use warnings; |
466 | use parent 'DBIx::Class::Core'; |
467 | use aliased 'DBIx::Class::ResultSource::MultipleTableInheritance' |
468 | => 'MTI'; |
469 | |
470 | __PACKAGE__->table_class(MTI); |
146ec120 |
471 | __PACKAGE__->table('coffee'); |
472 | __PACKAGE__->add_columns( |
f8864134 |
473 | "id", { data_type => "integer" }, |
474 | "flavor", { |
475 | data_type => "text", |
476 | default_value => "good" }, |
146ec120 |
477 | ); |
478 | |
479 | __PACKAGE__->set_primary_key("id"); |
480 | |
481 | 1; |
482 | } |
483 | |
484 | { |
f8864134 |
485 | package Cafe::Result::Sumatra; |
146ec120 |
486 | |
f8864134 |
487 | use parent 'Cafe::Result::Coffee'; |
146ec120 |
488 | |
489 | __PACKAGE__->table('sumatra'); |
490 | |
f8864134 |
491 | __PACKAGE__->add_columns( "aroma", |
492 | { data_type => "text" } |
146ec120 |
493 | ); |
494 | |
495 | 1; |
496 | } |
5fa55fff |
497 | |
146ec120 |
498 | ... |
499 | |
f8864134 |
500 | my $schema = Cafe->connect($dsn,$user,$pass); |
146ec120 |
501 | |
f8864134 |
502 | my $cup = $schema->resultset('Sumatra'); |
146ec120 |
503 | |
f8864134 |
504 | print STDERR Dwarn $cup->result_source->columns; |
146ec120 |
505 | |
f8864134 |
506 | "id" |
507 | "flavor" |
508 | "aroma" |
509 | .. |
146ec120 |
510 | |
f5c54951 |
511 | Inherit from this package and you can make a resultset class from a view, but |
512 | that's more than a little bit misleading: the result is B<transparently |
513 | writable>. |
146ec120 |
514 | |
f5c54951 |
515 | This is accomplished through the use of stored procedures that map changes |
516 | written to the view to changes to the underlying concrete tables. |
146ec120 |
517 | |
518 | =head1 WHY? |
519 | |
f5c54951 |
520 | In many applications, many classes are subclasses of others. Let's say you |
521 | have this schema: |
146ec120 |
522 | |
523 | # Conceptual domain model |
5fa55fff |
524 | |
146ec120 |
525 | class User { |
f5c54951 |
526 | has id, |
527 | has name, |
528 | has password |
146ec120 |
529 | } |
530 | |
531 | class Investor { |
532 | has id, |
533 | has name, |
534 | has password, |
535 | has dollars |
536 | } |
537 | |
538 | That's redundant. Hold on a sec... |
539 | |
540 | class User { |
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541 | has id, |
542 | has name, |
543 | has password |
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544 | } |
545 | |
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546 | class Investor extends User { |
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547 | has dollars |
548 | } |
549 | |
550 | Good idea, but how to put this into code? |
551 | |
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552 | One far-too common and absolutely horrendous solution is to have a "checkbox" |
553 | in your database: a nullable "investor" column, which entails a nullable |
554 | "dollars" column, in the user table. |
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555 | |
556 | create table "user" ( |
557 | "id" integer not null primary key autoincrement, |
558 | "name" text not null, |
559 | "password" text not null, |
560 | "investor" tinyint(1), |
561 | "dollars" integer |
562 | ); |
563 | |
564 | Let's not discuss that further. |
565 | |
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566 | A second, better, solution is to break out the two tables into user and |
567 | investor: |
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568 | |
569 | create table "user" ( |
570 | "id" integer not null primary key autoincrement, |
571 | "name" text not null, |
572 | "password" text not null |
573 | ); |
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574 | |
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575 | create table "investor" ( |
576 | "id" integer not null references user("id"), |
577 | "dollars" integer |
578 | ); |
579 | |
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580 | So that investor's PK is just an FK to the user. We can clearly see the class |
581 | hierarchy here, in which investor is a subclass of user. In DBIx::Class |
582 | applications, this second strategy looks like: |
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583 | |
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584 | my $user_rs = $schema->resultset('User'); |
585 | my $new_user = $user_rs->create( |
586 | name => $args->{name}, |
587 | password => $args->{password}, |
588 | ); |
589 | |
590 | ... |
591 | |
592 | my $new_investor = $schema->resultset('Investor')->create( |
593 | id => $new_user->id, |
594 | dollars => $args->{dollars}, |
595 | ); |
596 | |
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597 | One can cope well with the second strategy, and it seems to be the most popular |
598 | smart choice. |
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599 | |
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600 | =head1 HOW? |
601 | |
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602 | There is a third strategy implemented here. Make the database do more of the |
603 | work: hide the nasty bits so we don't have to handle them unless we really want |
604 | to. It'll save us some typing and it'll make for more expressive code. What if |
605 | we could do this: |
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606 | |
607 | my $new_investor = $schema->resultset('Investor')->create( |
608 | name => $args->{name}, |
609 | password => $args->{password}, |
610 | dollars => $args->{dollars}, |
611 | ); |
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612 | |
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613 | And have it Just Work? The user... |
614 | |
615 | { |
616 | name => $args->{name}, |
617 | password => $args->{password}, |
618 | } |
619 | |
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620 | should be created behind the scenes, and the use of either user or investor |
621 | in your code should require no special handling. Deleting and updating |
622 | $new_investor should also delete or update the user row. |
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623 | |
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624 | It does. User and investor are both views, their concrete tables abstracted |
625 | away behind a set of rules and triggers. You would expect the above DBIC |
626 | create statement to look like this in SQL: |
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627 | |
628 | INSERT INTO investor ("name","password","dollars") VALUES (...); |
629 | |
630 | But using MTI, it is really this: |
631 | |
632 | INSERT INTO _user_table ("username","password") VALUES (...); |
633 | INSERT INTO _investor_table ("id","dollars") VALUES (currval('_user_table_id_seq',...) ); |
634 | |
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635 | For deletes, the triggers fire in reverse, to preserve referential integrity |
636 | (foreign key constraints). For instance: |
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637 | |
638 | my $investor = $schema->resultset('Investor')->find({id => $args->{id}}); |
639 | $investor->delete; |
640 | |
641 | Becomes: |
642 | |
643 | DELETE FROM _investor_table WHERE ("id" = ?); |
644 | DELETE FROM _user_table WHERE ("id" = ?); |
645 | |
646 | |
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647 | =head1 METHODS |
648 | |
649 | =over |
650 | |
651 | =item new |
652 | |
653 | |
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654 | MTI find the parents, if any, of your resultset class and adds them to the |
655 | list of parent_sources for the table. |
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656 | |
657 | |
658 | =item add_additional_parents |
659 | |
660 | |
661 | Continuing with coffee: |
662 | |
663 | __PACKAGE__->result_source_instance->add_additional_parents( |
664 | qw/ |
665 | MyApp::Schema::Result::Beverage |
666 | MyApp::Schema::Result::Liquid |
667 | / |
668 | ); |
669 | |
670 | This just lets you manually add additional parents beyond the ones MTI finds. |
671 | |
672 | =item add_additional_parent |
673 | |
674 | __PACKAGE__->result_source_instance->add_additional_parent( |
675 | MyApp::Schema::Result::Beverage |
676 | ); |
677 | |
678 | You can also add just one. |
679 | |
680 | =item attach_additional_sources |
681 | |
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682 | MTI takes the parents' sources and relationships, creates a new |
683 | DBIx::Class::Table object from them, and registers this as a new, raw, source |
684 | in the schema, e.g., |
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685 | |
686 | use MyApp::Schema; |
687 | |
688 | print STDERR map { "$_\n" } MyApp::Schema->sources; |
689 | |
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690 | # Coffee |
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691 | # Beverage |
692 | # Liquid |
693 | # Sumatra |
694 | # Raw::Sumatra |
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695 | |
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696 | Raw::Sumatra will be used to generate the view. |
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697 | |
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698 | =item view_definition |
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699 | |
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700 | This takes the raw table and generates the view (and stored procedures) you will use. |
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701 | |
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702 | =back |
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703 | |
704 | =head1 AUTHOR |
705 | |
706 | Matt S. Trout, E<lt>mst@shadowcatsystems.co.ukE<gt> |
707 | |
708 | =head2 CONTRIBUTORS |
709 | |
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710 | Amiri Barksdale, E<lt>amiri@roosterpirates.comE<gt> |
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711 | |
712 | =head1 COPYRIGHT |
713 | |
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714 | Copyright (c) 2011 the DBIx::Class::ResultSource::MultipleTableInheritance |
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715 | L</AUTHOR> and L</CONTRIBUTORS> as listed above. |
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716 | |
717 | =head1 LICENSE |
718 | |
719 | This library is free software; you can redistribute it and/or modify |
720 | it under the same terms as Perl itself. |
721 | |
722 | =head1 SEE ALSO |
723 | |
724 | L<DBIx::Class> |
725 | L<DBIx::Class::ResultSource> |
726 | |
727 | =cut |