Reflect ON DELETE and ON UPDATE for SQLite foreign keys

Co-authored-by: Mike Bayer <mike_mp@zzzcomputing.com>
Change-Id: Icd77ddbf851b1950f767022d67c8142b1b3c50f3
Pull-request: https://github.com/zzzeek/sqlalchemy/pull/244

4 files changed, 68 insertions, 4 deletions

diff --git a/doc/build/changelog/changelog_11.rst b/doc/build/changelog/changelog_11.rst
index b872f12ab..40fa46b7c 100644
--- a/doc/build/changelog/changelog_11.rst
+++ b/doc/build/changelog/changelog_11.rst
@@ -53,6 +53,14 @@
         Pull request courtesy Josh Marlow.
 
     .. change::
+        :tags: feature, sqlite
+        :pullreq: github:244
+
+        The SQLite dialect now reflects ON UPDATE and ON DELETE phrases
+        within foreign key constraints.  Pull request courtesy
+        Michal Petrucha.
+
+    .. change::
         :tags: bug, mssql
         :pullreq: bitbucket:58
 
diff --git a/doc/build/changelog/migration_11.rst b/doc/build/changelog/migration_11.rst
index 479681798..7ebaf84a0 100644
--- a/doc/build/changelog/migration_11.rst
+++ b/doc/build/changelog/migration_11.rst
@@ -2274,6 +2274,14 @@ both within the method :meth:`.Inspector.get_check_constraints` as well
 as within :class:`.Table` reflection within the :attr:`.Table.constraints`
 collection.
 
+ON DELETE and ON UPDATE foreign key phrases now reflect
+-------------------------------------------------------
+
+The :class:`.Inspector` will now include ON DELETE and ON UPDATE
+phrases from foreign key constraints on the SQLite dialect, and the
+:class:`.ForeignKeyConstraint` object as reflected as part of a
+:class:`.Table` will also indicate these phrases.
+
 Dialect Improvements and Changes - SQL Server
 =============================================
 
diff --git a/lib/sqlalchemy/dialects/sqlite/base.py b/lib/sqlalchemy/dialects/sqlite/base.py
index 2fe10556b..85ebaaa1d 100644
--- a/lib/sqlalchemy/dialects/sqlite/base.py
+++ b/lib/sqlalchemy/dialects/sqlite/base.py
@@ -1374,14 +1374,17 @@ class SQLiteDialect(default.DefaultDialect):
             FK_PATTERN = (
                 '(?:CONSTRAINT (\w+) +)?'
                 'FOREIGN KEY *\( *(.+?) *\) +'
-                'REFERENCES +(?:(?:"(.+?)")|([a-z0-9_]+)) *\((.+?)\)'
+                'REFERENCES +(?:(?:"(.+?)")|([a-z0-9_]+)) *\((.+?)\) *'
+                '((?:ON (?:DELETE|UPDATE) '
+                '(?:SET NULL|SET DEFAULT|CASCADE|RESTRICT|NO ACTION) *)*)'
             )
 
             for match in re.finditer(FK_PATTERN, table_data, re.I):
                 (
                     constraint_name, constrained_columns,
                     referred_quoted_name, referred_name,
-                    referred_columns) = match.group(1, 2, 3, 4, 5)
+                    referred_columns, onupdatedelete) = \
+                    match.group(1, 2, 3, 4, 5, 6)
                 constrained_columns = list(
                     self._find_cols_in_sig(constrained_columns))
                 if not referred_columns:
@@ -1390,14 +1393,20 @@ class SQLiteDialect(default.DefaultDialect):
                     referred_columns = list(
                         self._find_cols_in_sig(referred_columns))
                 referred_name = referred_quoted_name or referred_name
+                options = {}
+                for token in re.split(r" *ON *", onupdatedelete):
+                    if token.startswith("DELETE"):
+                        options['ondelete'] = token[6:].strip()
+                    elif token.startswith("UPDATE"):
+                        options["onupdate"] = token[6:].strip()
                 yield (
                     constraint_name, constrained_columns,
-                    referred_name, referred_columns)
+                    referred_name, referred_columns, options)
         fkeys = []
 
         for (
             constraint_name, constrained_columns,
-                referred_name, referred_columns) in parse_fks():
+                referred_name, referred_columns, options) in parse_fks():
             sig = fk_sig(
                 constrained_columns, referred_name, referred_columns)
             if sig not in keys_by_signature:
@@ -1411,6 +1420,8 @@ class SQLiteDialect(default.DefaultDialect):
                 continue
             key = keys_by_signature.pop(sig)
             key['name'] = constraint_name
+            if options:
+                key['options'] = options
             fkeys.append(key)
         # assume the remainders are the unnamed, inline constraints, just
         # use them as is as it's extremely difficult to parse inline
diff --git a/test/dialect/test_sqlite.py b/test/dialect/test_sqlite.py
index dde9da086..16a628777 100644
--- a/test/dialect/test_sqlite.py
+++ b/test/dialect/test_sqlite.py
@@ -1146,6 +1146,16 @@ class ConstraintReflectionTest(fixtures.TestBase):
 
             # will contain an "autoindex"
             conn.execute("create table o (foo varchar(20) primary key)")
+            conn.execute(
+                "CREATE TABLE onud_test (id INTEGER PRIMARY KEY, "
+                "c1 INTEGER, c2 INTEGER, c3 INTEGER, "
+                "CONSTRAINT fk1 FOREIGN KEY (c1) REFERENCES a1(id) "
+                "ON DELETE SET NULL, "
+                "CONSTRAINT fk2 FOREIGN KEY (c2) REFERENCES a1(id) "
+                "ON UPDATE CASCADE, "
+                "CONSTRAINT fk3 FOREIGN KEY (c3) REFERENCES a2(id) "
+                "ON DELETE CASCADE ON UPDATE SET NULL)"
+            )
 
             conn.execute(
                 "CREATE TABLE cp ("
@@ -1283,6 +1293,33 @@ class ConstraintReflectionTest(fixtures.TestBase):
              'constrained_columns': ['q', 'p']}]
         )
 
+    def test_foreign_key_ondelete_onupdate(self):
+        inspector = Inspector(testing.db)
+        fks = inspector.get_foreign_keys('onud_test')
+        eq_(
+            fks,
+            [
+                {
+                    'referred_table': 'a1', 'referred_columns': ['id'],
+                    'referred_schema': None, 'name': 'fk1',
+                    'constrained_columns': ['c1'],
+                    'options': {'ondelete': 'SET NULL'}
+                },
+                {
+                    'referred_table': 'a1', 'referred_columns': ['id'],
+                    'referred_schema': None, 'name': 'fk2',
+                    'constrained_columns': ['c2'],
+                    'options': {'onupdate': 'CASCADE'}
+                },
+                {
+                    'referred_table': 'a2', 'referred_columns': ['id'],
+                    'referred_schema': None, 'name': 'fk3',
+                    'constrained_columns': ['c3'],
+                    'options': {'ondelete': 'CASCADE', 'onupdate': 'SET NULL'}
+                },
+            ]
+        )
+
     def test_dont_reflect_autoindex(self):
         inspector = Inspector(testing.db)
         eq_(inspector.get_indexes('o'), [])