For more information on generating complex queries, see
L<SQL::Abstract/WHERE CLAUSES>.
+=head3 Arbitrary SQL through a custom ResultSource
+
+Sometimes you have to run arbitrary SQL because your query is too complex
+(e.g. it contains Unions, Sub-Selects, Stored Procedures, etc.) or has to
+be optimized for your database in a special way, but you still want to
+get the results as a L<DBIx::Class::ResultSet>.
+The recommended way to accomplish this is by defining a separate ResultSource
+for your query. You can then inject complete SQL statements using a scalar
+reference (this is a feature of L<SQL::Abstract>).
+
+Say you want to run a complex custom query on your user data, here's what
+you have to add to your User class:
+
+ package My::Schema::User;
+
+ use base qw/DBIx::Class/;
+
+ # ->load_components, ->table, ->add_columns, etc.
+
+ # Make a new ResultSource based on the User class
+ my $source = __PACKAGE__->result_source_instance();
+ my $new_source = $source->new( $source );
+ $new_source->source_name( 'UserFriendsComplex' );
+
+ # Hand in your query as a scalar reference
+ # It will be added as a sub-select after FROM,
+ # so pay attention to the surrounding brackets!
+ $new_source->name( \<<SQL );
+ ( SELECT u.* FROM user u
+ INNER JOIN user_friends f ON u.id = f.user_id
+ WHERE f.friend_user_id = ?
+ UNION
+ SELECT u.* FROM user u
+ INNER JOIN user_friends f ON u.id = f.friend_user_id
+ WHERE f.user_id = ? )
+ SQL
+
+ # Finally, register your new ResultSource with your Schema
+ My::Schema->register_source( 'UserFriendsComplex' => $new_source );
+
+Next, you can execute your complex query using bind parameters like this:
+
+ my $friends = [ $schema->resultset( 'UserFriendsComplex' )->search( {},
+ {
+ bind => [ 12345, 12345 ]
+ }
+ ) ];
+
+... and you'll get back a perfect L<DBIx::Class::ResultSet>.
+
=head3 Using specific columns
When you only want specific columns from a table, you can use
my $ordered_cds = $schema->resultset('CD')->search_cds_ordered();
-
-=head3 Predefined searches without writing a ResultSet class
-
-Alternatively you can automatically generate a DBIx::Class::ResultSet
-class by using the ResultSetManager component and tagging your method
-as ResultSet:
-
- __PACKAGE__->load_components(qw/ ResultSetManager Core /);
-
- sub search_cds_ordered : ResultSet {
- my ($self) = @_;
- return $self->search(
- {},
- { order_by => 'name DESC' },
- );
- }
-
-Then call your method in the same way from your code:
-
- my $ordered_cds = $schema->resultset('CD')->search_cds_ordered();
-
=head2 Using joins and prefetch
You can use the C<join> attribute to allow searching on, or sorting your
=head2 Transactions
As of version 0.04001, there is improved transaction support in
-L<DBIx::Class::Storage::DBI> and L<DBIx::Class::Schema>. Here is an
+L<DBIx::Class::Storage> and L<DBIx::Class::Schema>. Here is an
example of the recommended way to use it:
my $genus = $schema->resultset('Genus')->find(12);
C<next::method>.
sub new {
- my ( $class, $attrs ) = @_;
+ my ( $self, $attrs ) = @_;
$attrs->{foo} = 'bar' unless defined $attrs->{foo};
- $class->next::method($attrs);
+ my $new = $class->next::method($attrs);
+
+ return $new;
}
For more information about C<next::method>, look in the L<Class::C3>
ways to write your own base classes to do this.
People looking for ways to do "triggers" with DBIx::Class are probably
-just looking for this.
+just looking for this.
=head2 Stringification
=head2 Overloading methods
-L<DBIx::Class> uses the L<Class::C3> package, which provides for redispatch of
-method calls. You have to use calls to C<next::method> to overload methods.
-More information on using L<Class::C3> with L<DBIx::Class> can be found in
+L<DBIx::Class> uses the L<Class::C3> package, which provides for redispatch of
+method calls, useful for things like default values and triggers. You have to
+use calls to C<next::method> to overload methods. More information on using
+L<Class::C3> with L<DBIx::Class> can be found in
L<DBIx::Class::Manual::Component>.
=head3 Changing one field whenever another changes
=head2 Profiling
-When you enable L<DBIx::Class::Storage::DBI>'s debugging it prints the SQL
+When you enable L<DBIx::Class::Storage>'s debugging it prints the SQL
executed as well as notifications of query completion and transaction
begin/commit. If you'd like to profile the SQL you can subclass the
L<DBIx::Class::Storage::Statistics> class and write your own profiling
DBIx::Class is not built for speed, it's built for convenience and
ease of use, but sometimes you just need to get the data, and skip the
-fancy objects. Luckily this is also fairly easy using
-C<inflate_result>:
-
- # Define a class which just returns the results as a hashref:
- package My::HashRefInflator;
-
- ## $me is the hashref of cols/data from the immediate resultsource
- ## $prefetch is a deep hashref of all the data from the prefetched
- ## related sources.
+fancy objects.
+
+To do this simply use L<DBIx::Class::ResultClass::HashRefInflator>.
+
+ my $rs = $schema->resultset('CD');
+
+ $rs->result_class('DBIx::Class::ResultClass::HashRefInflator');
+
+ my $hash_ref = $rs->find(1);
+
+Wasn't that easy?
+
+=head2 Get raw data for blindingly fast results
- sub mk_hash {
- my ($me, $rest) = @_;
+If the C<inflate_result> solution above is not fast enough for you, you
+can use a DBIx::Class to return values exactly as they come out of the
+data base with none of the convenience methods wrapped round them.
- return { %$me,
- map { ($_ => mk_hash(@{$rest->{$_}})) } keys %$rest
- };
- }
+This is used like so:-
- sub inflate_result {
- my ($self, $source, $me, $prefetch) = @_;
- return mk_hash($me, $prefetch);
+ my $cursor = $rs->cursor
+ while (my @vals = $cursor->next) {
+ # use $val[0..n] here
}
- # Change the object inflation to a hashref for just this resultset:
- $rs->result_class('My::HashRefInflator');
-
- my $datahashref = $rs->next;
- foreach my $col (keys %$datahashref) {
- if(!ref($datahashref->{$col})) {
- # It's a plain value
- }
- elsif(ref($datahashref->{$col} eq 'HASH')) {
- # It's a related value in a hashref
- }
- }
+You will need to map the array offsets to particular columns (you can
+use the I<select> attribute of C<search()> to force ordering).
=head2 Want to know if find_or_create found or created a row?
projects / dbsrgits/DBIx-Class.git / blobdiff