Add handling of referential actions for foreign key constraints.

mysql2pgsql/lib/mysql_reader.py

@@ -10,6 +10,16 @@
 re_column_length = re.compile(r'\((\d+)\)')
 re_column_precision = re.compile(r'\((\d+),(\d+)\)')
 re_key_1 = re.compile(r'CONSTRAINT `(\w+)` FOREIGN KEY \(`(\w+)`\) REFERENCES `(\w+)` \(`(\w+)`\)')
+# NB: according to the MySQL docs (5.5):
+# SET DEFAULT: This action is recognized by the parser, but InnoDB rejects
+# table definitions containing ON DELETE SET DEFAULT or ON UPDATE
+# SET DEFAULT clauses.
+# Thus not searching for it. RESTRICT is the default behaviour and
+# SHOW CREATE TABLE will _not_ output it (even when explicitly defined before).
+# RESTRICT is assumed as default for Postgres if nothing is defined
+# according to SHOW CREATE TABLE info.
+re_key_1_on_delete = re.compile(r'ON DELETE (NO ACTION|CASCADE|SET NULL)')
+re_key_1_on_update = re.compile(r'ON UPDATE (NO ACTION|CASCADE|SET NULL)')
 re_key_2 = re.compile(r'KEY `(\w+)` \((.*)\)')
 re_key_3 = re.compile(r'PRIMARY KEY \((.*)\)')
 
@@ -160,6 +170,13 @@ def _load_indexes(self):
                     index['column'] = match_data.group(2)
                     index['ref_table'] = match_data.group(3)
                     index['ref_column'] = match_data.group(4)
+                    # NB: MySQL handles not defining a referential action,
+                    # NO ACTION and RESTRICT all like RESTRICT. That's why i
+                    # chose RESTRICT as default for the translation to Postgres.
+                    ondel_match = re_key_1_on_delete.search(line)
+                    index['on_delete'] = ondel_match.group(1) if ondel_match else 'RESTRICT'
+                    onupd_match = re_key_1_on_update.search(line)
+                    index['on_update'] = onupd_match.group(1) if onupd_match else 'RESTRICT'
                     self._foreign_keys.append(index)
                     continue
                 match_data = re_key_2.search(line)

mysql2pgsql/lib/postgres_writer.py

@@ -251,11 +251,13 @@ def write_constraints(self, table):
         constraint_sql = []
         for key in table.foreign_keys:
             constraint_sql.append("""ALTER TABLE "%(table_name)s" ADD FOREIGN KEY ("%(column_name)s")
-            REFERENCES "%(ref_table_name)s"(%(ref_column_name)s);""" % {
+            REFERENCES "%(ref_table_name)s"(%(ref_column_name)s) %(on_delete)s %(on_update)s;""" % {
                 'table_name': table.name,
                 'column_name': key['column'],
                 'ref_table_name': key['ref_table'],
-                'ref_column_name': key['ref_column']})
+                'ref_column_name': key['ref_column'],
+                'on_delete': key['on_delete'] if key['on_delete'] == '' else 'ON DELETE %s' % (key['on_delete']),
+                'on_update': key['on_update'] if key['on_update'] == '' else 'ON UPDATE %s' % (key['on_update'])})
         return constraint_sql
 
     def close(self):