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 : $return_value;
238 Starts a transaction.
240 See the preferred L</txn_do> method, which allows for
241 an entire code block to be executed transactionally.
245 sub txn_begin { die "Virtual method!" }
249 Issues a commit of the current transaction.
253 sub txn_commit { die "Virtual method!" }
257 Issues a rollback of the current transaction. A nested rollback will
258 throw a L<DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION> exception,
259 which allows the rollback to propagate to the outermost transaction.
263 sub txn_rollback { die "Virtual method!" }
265 =head2 txn_scope_guard
267 Return an object that does stuff.
271 sub txn_scope_guard {
272 return DBIx::Class::Storage::TxnScopeGuard->new($_[0]);
277 Returns a C<sql_maker> object - normally an object of class
278 C<DBIC::SQL::Abstract>.
282 sub sql_maker { die "Virtual method!" }
286 Causes trace information to be emitted on the C<debugobj> object.
287 (or C<STDERR> if C<debugobj> has not specifically been set).
289 This is the equivalent to setting L</DBIC_TRACE> in your
294 Set or retrieve the filehandle used for trace/debug output. This should be
295 an IO::Handle compatible ojbect (only the C<print> method is used. Initially
296 set to be STDERR - although see information on the
297 L<DBIC_TRACE> environment variable.
304 if ($self->debugobj->can('debugfh')) {
305 return $self->debugobj->debugfh(@_);
311 Sets or retrieves the object used for metric collection. Defaults to an instance
312 of L<DBIx::Class::Storage::Statistics> that is compatible with the original
313 method of using a coderef as a callback. See the aforementioned Statistics
314 class for more information.
318 Sets a callback to be executed each time a statement is run; takes a sub
319 reference. Callback is executed as $sub->($op, $info) where $op is
320 SELECT/INSERT/UPDATE/DELETE and $info is what would normally be printed.
322 See L<debugobj> for a better way.
329 if ($self->debugobj->can('callback')) {
330 return $self->debugobj->callback(@_);
336 The cursor class for this Storage object.
342 Deploy the tables to storage (CREATE TABLE and friends in a SQL-based
343 Storage class). This would normally be called through
344 L<DBIx::Class::Schema/deploy>.
348 sub deploy { die "Virtual method!" }
352 The arguments of C<connect_info> are always a single array reference,
353 and are Storage-handler specific.
355 This is normally accessed via L<DBIx::Class::Schema/connection>, which
356 encapsulates its argument list in an arrayref before calling
357 C<connect_info> here.
361 sub connect_info { die "Virtual method!" }
365 Handle a select statement.
369 sub select { die "Virtual method!" }
373 Handle an insert statement.
377 sub insert { die "Virtual method!" }
381 Handle an update statement.
385 sub update { die "Virtual method!" }
389 Handle a delete statement.
393 sub delete { die "Virtual method!" }
397 Performs a select, fetch and return of data - handles a single row
402 sub select_single { die "Virtual method!" }
404 =head2 columns_info_for
406 Returns metadata for the given source's columns. This
407 is *deprecated*, and will be removed before 1.0. You should
408 be specifying the metadata yourself if you need it.
412 sub columns_info_for { die "Virtual method!" }
414 =head1 ENVIRONMENT VARIABLES
418 If C<DBIC_TRACE> is set then trace information
419 is produced (as when the L<debug> method is set).
421 If the value is of the form C<1=/path/name> then the trace output is
422 written to the file C</path/name>.
424 This environment variable is checked when the storage object is first
425 created (when you call connect on your schema). So, run-time changes
426 to this environment variable will not take effect unless you also
427 re-connect on your schema.
429 =head2 DBIX_CLASS_STORAGE_DBI_DEBUG
431 Old name for DBIC_TRACE
435 L<DBIx::Class::Storage::DBI> - reference storage inplementation using SQL::Abstract and DBI.
439 Matt S. Trout <mst@shadowcatsystems.co.uk>
441 Andy Grundman <andy@hybridized.org>
445 You may distribute this code under the same terms as Perl itself.