X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FRelationship.pm;h=d4926d187fb6a7cf3d35ae5731765b629bafa34e;hb=64ae166780d0cb2b9577e506da9b9b240c146d20;hp=b3f8507e7e0bc6f21768ee729d3129fa8f9a67e0;hpb=684af87666cd89229fd16c750cf1f77790e76a39;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/Relationship.pm b/lib/DBIx/Class/Relationship.pm
index b3f8507..d4926d1 100644
--- a/lib/DBIx/Class/Relationship.pm
+++ b/lib/DBIx/Class/Relationship.pm
@@ -39,6 +39,9 @@ See L<DBIx::Class::Manual::Cookbook> for more.
 
 =head1 DESCRIPTION
 
+The word I<Relationship> has a specific meaning in DBIx::Class, see
+the definition in the L<Glossary|DBIx::Class::Manual::Glossary/Relationship>.
+
 This class provides methods to set up relationships between the tables
 in your database model. Relationships are the most useful and powerful
 technique that L<DBIx::Class> provides. To create efficient database queries,
@@ -102,20 +105,20 @@ L<DBIx::Class::Relationship::Base>.
 
 All helper methods are called similar to the following template:
 
-  __PACKAGE__->$method_name('relname', 'Foreign::Class', $cond, $attrs);
-  
+  __PACKAGE__->$method_name('relname', 'Foreign::Class', \%cond | \@cond, \%attrs);
+
 Both C<$cond> and C<$attrs> are optional. Pass C<undef> for C<$cond> if
-you want to use the default value for it, but still want to set C<$attrs>.
+you want to use the default value for it, but still want to set C<\%attrs>.
 
 See L<DBIx::Class::Relationship::Base> for documentation on the
-attrubutes that are allowed in the C<$attrs> argument.
+attributes that are allowed in the C<\%attrs> argument.
 
 
 =head2 belongs_to
 
 =over 4
 
-=item Arguments: $accessor_name, $related_class, $our_fk_column|\%cond|\@cond?, \%attr?
+=item Arguments: $accessor_name, $related_class, $our_fk_column|\%cond|\@cond?, \%attrs?
 
 =back
 
@@ -208,6 +211,11 @@ Cascading deletes are off by default on a C<belongs_to>
 relationship. To turn them on, pass C<< cascade_delete => 1 >>
 in the $attr hashref.
 
+By default, DBIC will return undef and avoid querying the database if a
+C<belongs_to> accessor is called when any part of the foreign key IS NULL. To
+disable this behavior, pass C<< undef_on_null_fk => 0 >> in the C<$attr>
+hashref.
+
 NOTE: If you are used to L<Class::DBI> relationships, this is the equivalent
 of C<has_a>.
 
@@ -220,17 +228,17 @@ which can be assigned to relationships as well.
 
 =over 4
 
-=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond?, \%attr?
+=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond?, \%attrs?
 
 =back
 
-Creates a one-to-many relationship, where the corresponding elements
-of the foreign class store the calling class's primary key in one (or
-more) of the foreign class columns. This relationship defaults to using
-the end of this classes namespace as the foreign key in C<$related_class>
-to resolve the join, unless C<$their_fk_column> specifies the foreign
-key column in C<$related_class> or C<cond> specifies a reference to a
-join condition hash.
+Creates a one-to-many relationship where the foreign class refers to
+this class's primary key. This relationship refers to zero or more
+records in the foreign table (e.g. a C<LEFT JOIN>). This relationship 
+defaults to using the end of this classes namespace as the foreign key
+in C<$related_class> to resolve the join, unless C<$their_fk_column>
+specifies the foreign key column in C<$related_class> or C<cond>
+specifies a reference to a join condition hash.
 
 =over
 
@@ -289,7 +297,7 @@ OR condition.
     'My::DBIC::Schema::Book', 
     { 'foreign.author_id' => 'self.id' },
   );
-  
+
   # OR (similar result, assuming related_class is storing our PK, in "author")
   # (the "author" is guessed at from "Author" in the class namespace)
   My::DBIC::Schema::Author->has_many(
@@ -353,7 +361,7 @@ which can be assigned to relationships as well.
 
 =over 4
 
-=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond?, \%attr?
+=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond?, \%attrs?
 
 =back
 
@@ -433,11 +441,22 @@ methods and valid relationship attributes. Also see L<DBIx::Class::ResultSet>
 for a L<list of standard resultset attributes|DBIx::Class::ResultSet/ATTRIBUTES>
 which can be assigned to relationships as well.
 
+Note that if you supply a condition on which to join, if the column in the
+current table allows nulls (i.e., has the C<is_nullable> attribute set to a
+true value), than C<might_have> will warn about this because it's naughty and
+you shouldn't do that.  
+
+ "might_have/has_one" must not be on columns with is_nullable set to true (MySchema::SomeClass/key)
+
+If you must be naughty, you can suppress the warning by setting
+C<DBIC_DONT_VALIDATE_RELS> environment variable to a true value.  Otherwise,
+you probably just want to use C<DBIx::Class::Relationship/belongs_to>.
+
 =head2 has_one
 
 =over 4
 
-=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond?, \%attr?
+=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond?, \%attrs?
 
 =back
 
@@ -520,14 +539,23 @@ methods and valid relationship attributes. Also see L<DBIx::Class::ResultSet>
 for a L<list of standard resultset attributes|DBIx::Class::ResultSet/ATTRIBUTES>
 which can be assigned to relationships as well.
 
+Note that if you supply a condition on which to join, if the column in the
+current table allows nulls (i.e., has the C<is_nullable> attribute set to a
+true value), than warnings might apply just as with
+L<DBIx::Class::Relationship/might_have>.
+
 =head2 many_to_many
 
 =over 4
 
-=item Arguments: $accessor_name, $link_rel_name, $foreign_rel_name, \%attr?
+=item Arguments: $accessor_name, $link_rel_name, $foreign_rel_name, \%attrs?
 
 =back
 
+C<many_to_many> is a I<Relationship bridge> which has a specific
+meaning in DBIx::Class, see the definition in the
+L<Glossary|DBIx::Class::Manual::Glossary/Relationship bridge>.
+
 C<many_to_many> is not strictly a relationship in its own right. Instead, it is
 a bridge between two resultsets which provide the same kind of convenience
 accessors as true relationships provide. Although the accessor will return a