1 package DBIx::Class::Storage;
6 use base qw/DBIx::Class/;
8 use Scalar::Util qw/weaken/;
9 use Carp::Clan qw/^DBIx::Class/;
11 use DBIx::Class::Storage::TxnScopeGuard;
13 __PACKAGE__->mk_group_accessors('simple' => qw/debug debugobj schema/);
14 __PACKAGE__->mk_group_accessors('inherited' => 'cursor_class');
16 __PACKAGE__->cursor_class('DBIx::Class::Cursor');
18 sub cursor { shift->cursor_class(@_); }
20 package # Hide from PAUSE
21 DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION;
23 use overload '"' => sub {
24 'DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION'
30 return bless $self, $class;
33 package DBIx::Class::Storage;
37 DBIx::Class::Storage - Generic Storage Handler
41 A base implementation of common Storage methods. For specific
42 information about L<DBI>-based storage, see L<DBIx::Class::Storage::DBI>.
50 Instantiates the Storage object.
55 my ($self, $schema) = @_;
57 $self = ref $self if ref $self;
62 $new->set_schema($schema);
63 $new->debugobj(new DBIx::Class::Storage::Statistics());
67 my $debug_env = $ENV{DBIX_CLASS_STORAGE_DBI_DEBUG}
70 $new->debug(1) if $debug_env;
77 Used to reset the schema class or object which owns this
78 storage object, such as during L<DBIx::Class::Schema/clone>.
83 my ($self, $schema) = @_;
84 $self->schema($schema);
85 weaken($self->{schema}) if ref $self->{schema};
90 Returns true if we have an open storage connection, false
91 if it is not (yet) open.
95 sub connected { die "Virtual method!" }
99 Closes any open storage connection unconditionally.
103 sub disconnect { die "Virtual method!" }
105 =head2 ensure_connected
107 Initiate a connection to the storage if one isn't already open.
111 sub ensure_connected { die "Virtual method!" }
113 =head2 throw_exception
115 Throws an exception - croaks.
119 sub throw_exception {
122 $self->schema->throw_exception(@_) if $self->schema;
130 =item Arguments: C<$coderef>, @coderef_args?
132 =item Return Value: The return value of $coderef
136 Executes C<$coderef> with (optional) arguments C<@coderef_args> atomically,
137 returning its result (if any). If an exception is caught, a rollback is issued
138 and the exception is rethrown. If the rollback fails, (i.e. throws an
139 exception) an exception is thrown that includes a "Rollback failed" message.
143 my $author_rs = $schema->resultset('Author')->find(1);
144 my @titles = qw/Night Day It/;
147 # If any one of these fails, the entire transaction fails
148 $author_rs->create_related('books', {
150 }) foreach (@titles);
152 return $author->books;
157 $rs = $schema->txn_do($coderef);
160 if ($@) { # Transaction failed
161 die "something terrible has happened!" #
162 if ($@ =~ /Rollback failed/); # Rollback failed
164 deal_with_failed_transaction();
167 In a nested transaction (calling txn_do() from within a txn_do() coderef) only
168 the outermost transaction will issue a L</txn_commit>, and txn_do() can be
169 called in void, scalar and list context and it will behave as expected.
171 Please note that all of the code in your coderef, including non-DBIx::Class
172 code, is part of a transaction. This transaction may fail out halfway, or
173 it may get partially double-executed (in the case that our DB connection
174 failed halfway through the transaction, in which case we reconnect and
175 restart the txn). Therefore it is best that any side-effects in your coderef
176 are idempotent (that is, can be re-executed multiple times and get the
177 same result), and that you check up on your side-effects in the case of
183 my ($self, $coderef, @args) = @_;
185 ref $coderef eq 'CODE' or $self->throw_exception
186 ('$coderef must be a CODE reference');
188 my (@return_values, $return_value);
190 $self->txn_begin; # If this throws an exception, no rollback is needed
192 my $wantarray = wantarray; # Need to save this since the context
193 # inside the eval{} block is independent
194 # of the context that called txn_do()
197 # Need to differentiate between scalar/list context to allow for
198 # returning a list in scalar context to get the size of the list
201 @return_values = $coderef->(@args);
202 } elsif (defined $wantarray) {
204 $return_value = $coderef->(@args);
220 my $rollback_error = $@;
221 my $exception_class = "DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION";
222 $self->throw_exception($error) # propagate nested rollback
223 if $rollback_error =~ /$exception_class/;
225 $self->throw_exception(
226 "Transaction aborted: $error. Rollback failed: ${rollback_error}"
229 $self->throw_exception($error); # txn failed but rollback succeeded
233 return $wantarray ? @return_values : $return_value;
238 Starts a transaction.
240 See the preferred L</txn_do> method, which allows for
241 an entire code block to be executed transactionally.
245 sub txn_begin { die "Virtual method!" }
249 Issues a commit of the current transaction.
251 It does I<not> perform an actual storage commit unless there's a DBIx::Class
252 transaction currently in effect (i.e. you called L</txn_begin>).
256 sub txn_commit { die "Virtual method!" }
260 Issues a rollback of the current transaction. A nested rollback will
261 throw a L<DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION> exception,
262 which allows the rollback to propagate to the outermost transaction.
266 sub txn_rollback { die "Virtual method!" }
270 Arguments: $savepoint_name?
272 Created a new savepoint using the name provided as argument. If no name
273 is provided, a random name will be used.
277 sub svp_begin { die "Virtual method!" }
281 Arguments: $savepoint_name?
283 Release the savepoint provided as argument. If none is provided,
284 release the savepoint created most recently. This will implicitly
285 release all savepoints created after the one explicitly released as well.
289 sub svp_release { die "Virtual method!" }
293 Arguments: $savepoint_name?
295 Rollback to the savepoint provided as argument. If none is provided,
296 rollback to the savepoint created most recently. This will implicitly
297 release all savepoints created after the savepoint we rollback to.
301 sub svp_rollback { die "Virtual method!" }
305 =head2 txn_scope_guard
307 An alternative way of transaction handling based on
308 L<DBIx::Class::Storage::TxnScopeGuard>:
310 my $txn_guard = $storage->txn_scope_guard;
317 If an exception occurs, or the guard object otherwise leaves the scope
318 before C<< $txn_guard->commit >> is called, the transaction will be rolled
319 back by an explicit L</txn_rollback> call. In essence this is akin to
320 using a L</txn_begin>/L</txn_commit> pair, without having to worry
321 about calling L</txn_rollback> at the right places. Note that since there
322 is no defined code closure, there will be no retries and other magic upon
323 database disconnection. If you need such functionality see L</txn_do>.
327 sub txn_scope_guard {
328 return DBIx::Class::Storage::TxnScopeGuard->new($_[0]);
333 Returns a C<sql_maker> object - normally an object of class
334 C<DBIx::Class::SQLAHacks>.
338 sub sql_maker { die "Virtual method!" }
342 Causes trace information to be emitted on the C<debugobj> object.
343 (or C<STDERR> if C<debugobj> has not specifically been set).
345 This is the equivalent to setting L</DBIC_TRACE> in your
350 Set or retrieve the filehandle used for trace/debug output. This should be
351 an IO::Handle compatible ojbect (only the C<print> method is used. Initially
352 set to be STDERR - although see information on the
353 L<DBIC_TRACE> environment variable.
360 if ($self->debugobj->can('debugfh')) {
361 return $self->debugobj->debugfh(@_);
367 Sets or retrieves the object used for metric collection. Defaults to an instance
368 of L<DBIx::Class::Storage::Statistics> that is compatible with the original
369 method of using a coderef as a callback. See the aforementioned Statistics
370 class for more information.
374 Sets a callback to be executed each time a statement is run; takes a sub
375 reference. Callback is executed as $sub->($op, $info) where $op is
376 SELECT/INSERT/UPDATE/DELETE and $info is what would normally be printed.
378 See L<debugobj> for a better way.
385 if ($self->debugobj->can('callback')) {
386 return $self->debugobj->callback(@_);
392 The cursor class for this Storage object.
398 Deploy the tables to storage (CREATE TABLE and friends in a SQL-based
399 Storage class). This would normally be called through
400 L<DBIx::Class::Schema/deploy>.
404 sub deploy { die "Virtual method!" }
408 The arguments of C<connect_info> are always a single array reference,
409 and are Storage-handler specific.
411 This is normally accessed via L<DBIx::Class::Schema/connection>, which
412 encapsulates its argument list in an arrayref before calling
413 C<connect_info> here.
417 sub connect_info { die "Virtual method!" }
421 Handle a select statement.
425 sub select { die "Virtual method!" }
429 Handle an insert statement.
433 sub insert { die "Virtual method!" }
437 Handle an update statement.
441 sub update { die "Virtual method!" }
445 Handle a delete statement.
449 sub delete { die "Virtual method!" }
453 Performs a select, fetch and return of data - handles a single row
458 sub select_single { die "Virtual method!" }
460 =head2 columns_info_for
462 Returns metadata for the given source's columns. This
463 is *deprecated*, and will be removed before 1.0. You should
464 be specifying the metadata yourself if you need it.
468 sub columns_info_for { die "Virtual method!" }
470 =head1 ENVIRONMENT VARIABLES
474 If C<DBIC_TRACE> is set then trace information
475 is produced (as when the L<debug> method is set).
477 If the value is of the form C<1=/path/name> then the trace output is
478 written to the file C</path/name>.
480 This environment variable is checked when the storage object is first
481 created (when you call connect on your schema). So, run-time changes
482 to this environment variable will not take effect unless you also
483 re-connect on your schema.
485 =head2 DBIX_CLASS_STORAGE_DBI_DEBUG
487 Old name for DBIC_TRACE
491 L<DBIx::Class::Storage::DBI> - reference storage implementation using
492 SQL::Abstract and DBI.
496 Matt S. Trout <mst@shadowcatsystems.co.uk>
498 Andy Grundman <andy@hybridized.org>
502 You may distribute this code under the same terms as Perl itself.