expand relationship_attrs POD

Explain the defaults for relationship attributes, how they are
overridden by the actual database values for foreign keys and can be
overridden by the user via this attribute.

Also explain how defaults are chosen for different databases for
belongs_to rels.

diff --git a/lib/DBIx/Class/Schema/Loader/Base.pm b/lib/DBIx/Class/Schema/Loader/Base.pm
index c93d28d..ba20fc4 100644 (file)
--- a/lib/DBIx/Class/Schema/Loader/Base.pm
+++ b/lib/DBIx/Class/Schema/Loader/Base.pm
@@ -389,15 +389,17 @@ override the introspected attributes of the foreign key if any.
 For example:
 
   relationship_attrs => {
-    has_many => { cascade_delete => 1, cascade_copy => 1 },
+    has_many   => { cascade_delete => 1, cascade_copy => 1 },
+    might_have => { cascade_delete => 1, cascade_copy => 1 },
   },
 
 use this to turn L<DBIx::Class> cascades to on on your
-L<has_many|DBIx::Class::Relationship/has_many> relationships, they default to
-off.
+L<has_many|DBIx::Class::Relationship/has_many> and
+L<might_have|DBIx::Class::Relationship/might_have> relationships, they default
+to off.
 
 Can also be a coderef, for more precise control, in which case the coderef gets
-this hash of parameters:
+this hash of parameters (as a list:)
 
     rel_name        # the name of the relationship
     local_source    # the DBIx::Class::ResultSource object for the source the rel is *from*
@@ -430,6 +432,50 @@ For example:
         }
     },
 
+These are the default attributes:
+
+    has_many => {
+        cascade_delete => 0,
+        cascade_copy   => 0,
+    },
+    might_have => {
+        cascade_delete => 0,
+        cascade_copy   => 0,
+    },
+    belongs_to => {
+        on_delete => 'CASCADE',
+        on_update => 'CASCADE',
+        is_deferrable => 1,
+    },
+
+For L<belongs_to|DBIx::Class::Relationship/belongs_to> relationships, these
+defaults are overridden by the attributes introspected from the foreign key in
+the database, if this information is available (and the driver is capable of
+retrieving it.)
+
+This information overrides the defaults mentioned above, and is then itself
+overridden by the user's L</relationship_attrs> for C<belongs_to> if any are
+specified.
+
+In general, for most databases, for a plain foreign key with no rules, the
+values for a L<belongs_to|DBIx::Class::Relationship/belongs_to> relationship
+will be:
+
+    on_delete     => 'NO ACTION',
+    on_update     => 'NO ACTION',
+    is_deferrable => 0,
+
+In the cases where an attribute is not supported by the DB, a value matching
+the actual behavior is used, for example Oracle does not support C<ON UPDATE>
+rules, so C<on_update> is set to C<NO ACTION>. This is done so that the
+behavior of the schema is preserved when cross deploying to a different RDBMS
+such as SQLite for testing.
+
+In the cases where the DB does not support C<DEFERRABLE> foreign keys, the
+value is set to C<1> if L<DBIx::Class> has a working C<<
+$storage->with_deferred_fk_checks >>. This is done so that the same
+L<DBIx::Class> code can be used, and cross deployed from and to such databases.
+
 =head2 debug
 
 If set to true, each constructive L<DBIx::Class> statement the loader

diff --git a/lib/DBIx/Class/Schema/Loader/DBI/SQLite.pm b/lib/DBIx/Class/Schema/Loader/DBI/SQLite.pm
index eeb5276..b39b510 100644 (file)
--- a/lib/DBIx/Class/Schema/Loader/DBI/SQLite.pm
+++ b/lib/DBIx/Class/Schema/Loader/DBI/SQLite.pm
@@ -172,7 +172,7 @@ EOF
 
                 my ($deferrable_clause) = $ddl =~ /
                     "?\Q$local_col\E"? \s* (?:\w+\s*)* (?: \( \s* \d\+ (?:\s*,\s*\d+)* \s* \) )? \s*
-                    references \s* (?:\S+|".+?(?<!")") (?:\s* \( \s* "?\Q$remote_col\E"? \s* \))? \s*
+                    references \s+ (?:\S+|".+?(?<!")") (?:\s* \( \s* "?\Q$remote_col\E"? \s* \))? \s*
                     (?:(?:
                       on \s+ (?:delete|update) \s+ (?:set \s+ null|set \s+ default|cascade|restrict|no \s+ action)
                     |