Next, spend some time defining which data you need to store, and how
it relates to the other data you have. For some help on normalisation,
-go to L<http://b62.tripod.com/doc/dbbase.htm> or
-L<http://209.197.234.36/db/simple.html>.
+go to L<http://b62.tripod.com/doc/dbbase.htm>.
Now, decide whether you want to have the database itself be the
definitive source of information about the data layout, or your
->search({'created_time' => { '>=', '2006-06-01 00:00:00' } })
-Note that to use a function here you need to make the whole value into
-a scalar reference:
+Note that to use a function here you need to make it a scalar
+reference:
- ->search({'created_time' => \'>= yesterday()' })
+ ->search({'created_time' => { '>=', \'yesterday()' } })
=item .. search in several tables simultaneously?
query, which can be accessed similarly to a table, see your database
documentation for details.
-=item .. search using greater-than or less-than and database functions?
-
-To use functions or literal SQL with conditions other than equality
-you need to supply the entire condition, for example:
-
- my $interval = "< now() - interval '12 hours'";
- ->search({last_attempt => \$interval})
-
-and not:
-
- my $interval = "now() - interval '12 hours'";
- ->search({last_attempt => { '<' => \$interval } })
-
=item .. search with an SQL function on the left hand side?
To use an SQL function on the left hand side of a comparison:
- ->search({}, { where => \'YEAR(date_of_birth)=1979' });
-
-=begin hidden
+ ->search({ -nest => \[ 'YEAR(date_of_birth) = ?', [ plain_value => 1979 ] ] });
-(When the bind arg ordering bug is fixed, the previous example can be
-replaced with the following.)
-
- ->search({}, { where => \'YEAR(date_of_birth)=?', bind => [ 1979 ] });
-
-=end hidden
+Note: the C<plain_value> string in the C<< [ plain_value => 1979 ] >> part
+should be either the same as the name of the column (do this if the type of the
+return value of the function is the same as the type of the column) or
+otherwise it's essentially a dummy string currently (use C<plain_value> as a
+habit). It is used by L<DBIx::Class> to handle special column types.
Or, if you have quoting off:
=item .. fetch a single (or topmost) row?
-Sometimes you many only want a single record back from a search. A quick
-way to get that single row is to first run your search as usual:
-
- ->search->(undef, { order_by => "id DESC" })
-
-Then call L<DBIx::Class::ResultSet/slice> and ask it only to return 1 row:
-
- ->slice(0)
+See L<DBIx::Class::Manual::Cookbook/Retrieve_one_and_only_one_row_from_a_resultset>.
-These two calls can be combined into a single statement:
+A less readable way is to ask a regular search to return 1 row, using
+L<DBIx::Class::ResultSet/slice>:
->search->(undef, { order_by => "id DESC" })->slice(0)
-Why slice instead of L<DBIx::Class::ResultSet/first> or L<DBIx::Class::ResultSet/single>?
-If supported by the database, slice will use LIMIT/OFFSET to hint to the database that we
-really only need one row. This can result in a significant speed improvement.
+which (if supported by the database) will use LIMIT/OFFSET to hint to the
+database that we really only need one row. This can result in a significant
+speed improvement. The method using L<DBIx::Class::ResultSet/single> mentioned
+in the cookbook can do the same if you pass a C<rows> attribute to the search.
=item .. refresh a row from storage?
=item .. insert many rows of data efficiently?
+The C<populate> method in L<DBIx::Class::ResultSet> provides
+efficient bulk inserts.
+
=item .. update a collection of rows at the same time?
Create a resultset using a search, to filter the rows of data you
=back
+=head2 Custom methods in Result classes
+
+You can add custom methods that do arbitrary things, even to unrelated tables.
+For example, to provide a C<< $book->foo() >> method which searches the
+cd table, you'd could add this to Book.pm:
+
+ sub foo {
+ my ($self, $col_data) = @_;
+ return $self->result_source->schema->resultset('cd')->search($col_data);
+ }
+
+And invoke that on any Book Result object like so:
+
+ my $rs = $book->foo({ title => 'Down to Earth' });
+
+When two tables ARE related, L<DBIx::Class::Relationship::Base> provides many
+methods to find or create data in related tables for you. But if you want to
+write your own methods, you can.
+
+For example, to provide a C<< $book->foo() >> method to manually implement
+what create_related() from L<DBIx::Class::Relationship::Base> does, you could
+add this to Book.pm:
+
+ sub foo {
+ my ($self, $relname, $col_data) = @_;
+ return $self->related_resultset($relname)->create($col_data);
+ }
+
+Invoked like this:
+
+ my $author = $book->foo('author', { name => 'Fred' });
+
=head2 Misc
=over 4
using the tips in L<DBIx::Class::Manual::Cookbook/"Skip row object creation for faster results">
and L<DBIx::Class::Manual::Cookbook/"Get raw data for blindingly fast results">
+=item How do I override a run time method (e.g. a relationship accessor)?
+
+If you need access to the original accessor, then you must "wrap around" the original method.
+You can do that either with L<Moose::Manual::MethodModifiers> or L<Class::Method::Modifiers>.
+The code example works for both modules:
+
+ package Your::Schema::Group;
+ use Class::Method::Modifiers;
+
+ # ... declare columns ...
+
+ __PACKAGE__->has_many('group_servers', 'Your::Schema::GroupServer', 'group_id');
+ __PACKAGE__->many_to_many('servers', 'group_servers', 'server');
+
+ # if the server group is a "super group", then return all servers
+ # otherwise return only servers that belongs to the given group
+ around 'servers' => sub {
+ my $orig = shift;
+ my $self = shift;
+
+ return $self->$orig(@_) unless $self->is_super_group;
+ return $self->result_source->schema->resultset('Server')->all;
+ };
+
+If you just want to override the original method, and don't care about the data
+from the original accessor, then you have two options. Either use
+L<Method::Signatures::Simple> that does most of the work for you, or do
+it the "dirty way".
+
+L<Method::Signatures::Simple> way:
+
+ package Your::Schema::Group;
+ use Method::Signatures::Simple;
+
+ # ... declare columns ...
+
+ __PACKAGE__->has_many('group_servers', 'Your::Schema::GroupServer', 'group_id');
+ __PACKAGE__->many_to_many('servers', 'group_servers', 'server');
+
+ # The method keyword automatically injects the annoying my $self = shift; for you.
+ method servers {
+ return $self->result_source->schema->resultset('Server')->search({ ... });
+ }
+
+The dirty way:
+
+ package Your::Schema::Group;
+ use Sub::Name;
+
+ # ... declare columns ...
+
+ __PACKAGE__->has_many('group_servers', 'Your::Schema::GroupServer', 'group_id');
+ __PACKAGE__->many_to_many('servers', 'group_servers', 'server');
+
+ *servers = subname servers => sub {
+ my $self = shift;
+ return $self->result_source->schema->resultset('Server')->search({ ... });
+ };
+
=back
=head2 Notes for CDBI users
projects / dbsrgits/DBIx-Class.git / blobdiff