preserve db-specific options in schema.rb, fixes #148

basically any valid db-specific thing that you can already specify via
`options: "..."` will be preserved on the way back out.

for mysql that's:
* `ON UPDATE <action>`

for postgres that's:
* `ON UPDATE <action>`
* `ON DELETE SET DEFAULT` (doesn't map to a `:dependent` value)
* `DEFERRABLE` (`NOT DEFERRABLE` is the default)
* `INITIALLY DEFERRED` (`INITIALLY IMMEDIATE` is the default)
* `NOT VALID`

postgres' `MATCH <type>` is not supported, but that's already problematic
for `:options` since it is incompatible with `:dependent` (due to where it
appears in the statement), so ¯\_(ツ)_/¯

lib/foreigner/connection_adapters/mysql2_adapter.rb

@@ -26,12 +26,13 @@ def foreign_keys(table_name)
         fk_info.map do |row|
           options = {column: row['column'], name: row['name'], primary_key: row['primary_key']}
 
-          if create_table_info =~ /CONSTRAINT #{quote_column_name(row['name'])} FOREIGN KEY .* REFERENCES .* ON DELETE (CASCADE|SET NULL|RESTRICT)/
-            options[:dependent] = case $1
+          if create_table_info =~ /CONSTRAINT #{quote_column_name(row['name'])} FOREIGN KEY .* REFERENCES .*\)( ON DELETE (CASCADE|SET NULL|RESTRICT))? ?(.*)$/
+            options[:dependent] = case $2
               when 'CASCADE'  then :delete
               when 'SET NULL' then :nullify
               when 'RESTRICT' then :restrict
             end
+            options[:options] = $3 # e.g. ON UPDATE ...
           end
           ForeignKeyDefinition.new(table_name, row['to_table'], options)
         end

lib/foreigner/connection_adapters/postgresql_adapter.rb

@@ -3,9 +3,19 @@ module ConnectionAdapters
     module PostgreSQLAdapter
       include Foreigner::ConnectionAdapters::Sql2003
 
+      DEPENDENCY_CODE_ACTIONS = {'c' => 'CASCADE', 'n' => 'SET NULL', 'r' => 'RESTRICT', 'd' => 'SET DEFAULT'}
+
       def foreign_keys(table_name)
         fk_info = select_all %{
-          SELECT t2.relname AS to_table, a1.attname AS column, a2.attname AS primary_key, c.conname AS name, c.confdeltype AS dependency
+          SELECT t2.relname AS to_table
+               , a1.attname AS column
+               , a2.attname AS primary_key
+               , c.conname AS name
+               , c.confdeltype AS dependency
+               , c.confupdtype AS update_dependency
+               , c.condeferrable AS deferrable
+               , c.condeferred AS deferred
+            #{", c.convalidated AS valid" if postgresql_version >= 90100}
           FROM pg_constraint c
           JOIN pg_class t1 ON c.conrelid = t1.oid
           JOIN pg_class t2 ON c.confrelid = t2.oid
@@ -22,11 +32,23 @@ def foreign_keys(table_name)
           options = {column: row['column'], name: row['name'], primary_key: row['primary_key']}
 
           options[:dependent] = case row['dependency']
+            # NO ACTION is the default
+            # SET DEFAULT is handled below, since it is postgres-specific
             when 'c' then :delete
             when 'n' then :nullify
             when 'r' then :restrict
           end
 
+          extras = []
+          extras << "ON DELETE SET DEFAULT"      if row['dependency'] == 'd'
+          if update_action = DEPENDENCY_CODE_ACTIONS[row['update_dependency']]
+            extras << "ON UPDATE #{update_action}"
+          end
+          extras << 'DEFERRABLE'                 if row['deferrable'] == 't'
+          extras << 'INITIALLY DEFERRED'         if row['deferred'] == 't'
+          extras << 'NOT VALID'                  if row['valid'] == 'f'
+          options[:options] = extras.join(" ")
+
           ForeignKeyDefinition.new(table_name, row['to_table'], options)
         end
       end
@@ -35,4 +57,4 @@ def foreign_keys(table_name)
 end
 
 Foreigner::Adapter.safe_include :JdbcAdapter, Foreigner::ConnectionAdapters::PostgreSQLAdapter
-Foreigner::Adapter.safe_include :PostgreSQLAdapter, Foreigner::ConnectionAdapters::PostgreSQLAdapter
+Foreigner::Adapter.safe_include :PostgreSQLAdapter, Foreigner::ConnectionAdapters::PostgreSQLAdapter

lib/foreigner/schema_dumper.rb

@@ -21,6 +21,9 @@ def dump_foreign_key(foreign_key)
         if foreign_key.options[:dependent].present?
           statement_parts << ('dependent: ' + foreign_key.options[:dependent].inspect)
         end
+        if foreign_key.options[:options].present?
+          statement_parts << ('options: ' + foreign_key.options[:options].inspect)
+        end
 
         statement_parts.join(', ')
       end

test/foreigner/schema_dumper_test.rb

@@ -32,6 +32,7 @@ def foreign_keys(table, stream)
     assert_dump "add_foreign_key \"foos\", \"bars\", name: \"lulz\", primary_key: \"uuid\"", Foreigner::ConnectionAdapters::ForeignKeyDefinition.new('foos', 'bars', column: 'bar_id', primary_key: 'uuid', name: 'lulz')
     assert_dump "add_foreign_key \"foos\", \"bars\", name: \"lulz\", dependent: :delete", Foreigner::ConnectionAdapters::ForeignKeyDefinition.new('foos', 'bars', column: 'bar_id', primary_key: 'id', name: 'lulz', dependent: :delete)
     assert_dump "add_foreign_key \"foos\", \"bars\", name: \"lulz\", column: \"mamma_id\"", Foreigner::ConnectionAdapters::ForeignKeyDefinition.new('foos', 'bars', column: 'mamma_id', primary_key: 'id', name: 'lulz')
+    assert_dump "add_foreign_key \"foos\", \"bars\", name: \"lulz\", options: \"YOLO MAYBE DB-SPECIFIC!\"", Foreigner::ConnectionAdapters::ForeignKeyDefinition.new('foos', 'bars', column: 'bar_id', primary_key: 'id', name: 'lulz', options: "YOLO MAYBE DB-SPECIFIC!")
   end
 
   test 'all tables' do