=head2 Many-to-many relationships
-This is straightforward using L<DBIx::Class::Relationship::ManyToMany>:
+This is straightforward using L<ManyToMany|DBIx::Class::Relationship/many_to_many>:
package My::DB;
# ... set up connection ...
To make an object stringify itself as a single column, use something
like this (replace C<foo> with the column/method of your choice):
- use overload '""' => 'foo', fallback => 1;
+ use overload '""' => sub { shift->name}, fallback => 1;
For more complex stringification, you can use an anonymous subroutine:
### The statement below will print
print "I can do admin stuff\n" if $admin->can('do_admin_stuff');
+=head2 Skip object creation for faster results
+
+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
+ ## $prefetch is a deep hashref of all the data from the prefetched
+ ## related sources.
+
+ sub mk_hash {
+ my ($me, $rest) = @_;
+
+ return { %$me,
+ map { ($_ => mk_hash(@{$rest->{$_}})) } keys %$rest
+ };
+ }
+
+ sub inflate_result {
+ my ($self, $source, $me, $prefetch) = @_;
+ return mk_hash($me, $prefetch);
+ }
+
+ # 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
+ }
+ }
+
+=head2 Want to know if find_or_create found or created a row?
+
+Just use C<find_or_new> instead, then check C<in_storage>:
+
+ my $obj = $rs->find_or_new({ blah => 'blarg' });
+ unless ($obj->in_storage) {
+ $obj->insert;
+ # do whatever else you wanted if it was a new row
+ }
+
+=head3 Wrapping/overloading a column accessor
+
+Problem: Say you have a table "Camera" and want to associate a description
+with each camera. For most cameras, you'll be able to generate the description from
+the other columns. However, in a few special cases you may want to associate a
+custom description with a camera.
+
+Solution:
+
+In your database schema, define a description field in the "Camera" table that
+can contain text and null values.
+
+In DBIC, we'll overload the column accessor to provide a sane default if no
+custom description is defined. The accessor will either return or generate the
+description, depending on whether the field is null or not.
+
+First, in your "Camera" schema class, define the description field as follows:
+
+ __PACKAGE__->add_columns(description => { accessor => '_description' });
+
+Next, we'll define the accessor-wrapper subroutine:
+
+ sub description {
+ my $self = shift;
+
+ # If there is an update to the column, we'll let the original accessor
+ # deal with it.
+ return $self->_description(@_) if @_;
+
+ # Fetch the column value.
+ my $description = $self->_description;
+
+ # If there's something in the description field, then just return that.
+ return $description if defined $description && length $descripton;
+
+ # Otherwise, generate a description.
+ return $self->generate_description;
+ }
+
=cut