Implemented CHECK constraint reflection for SQLite and PostgreSQL

Co-Authored-By: Mike Bayer <mike_mp@zzzcomputing.com>
Change-Id: Ie6cf2d2958d1c567324db9e08fef2d3186e97350
Pull-request: https://bitbucket.org/zzzeek/sqlalchemy/pull-requests/80

2 files changed, 51 insertions, 0 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/base.py b/lib/sqlalchemy/dialects/postgresql/base.py
index 9d019b56e..fe3d29450 100644
--- a/lib/sqlalchemy/dialects/postgresql/base.py
+++ b/lib/sqlalchemy/dialects/postgresql/base.py
@@ -2497,6 +2497,31 @@ class PGDialect(default.DefaultDialect):
             for name, uc in uniques.items()
         ]
 
+    @reflection.cache
+    def get_check_constraints(
+            self, connection, table_name, schema=None, **kw):
+        table_oid = self.get_table_oid(connection, table_name, schema,
+                                       info_cache=kw.get('info_cache'))
+
+        CHECK_SQL = """
+            SELECT
+                cons.conname as name,
+                cons.consrc as src
+            FROM
+                pg_catalog.pg_constraint cons
+            WHERE
+                cons.conrelid = :table_oid AND
+                cons.contype = 'c'
+        """
+
+        c = connection.execute(sql.text(CHECK_SQL), table_oid=table_oid)
+
+        return [
+            {'name': name,
+             'sqltext': src[1:-1]}
+            for name, src in c.fetchall()
+            ]
+
     def _load_enums(self, connection, schema=None):
         schema = schema or self.default_schema_name
         if not self.supports_native_enum:
diff --git a/lib/sqlalchemy/dialects/sqlite/base.py b/lib/sqlalchemy/dialects/sqlite/base.py
index ddd869448..2fe10556b 100644
--- a/lib/sqlalchemy/dialects/sqlite/base.py
+++ b/lib/sqlalchemy/dialects/sqlite/base.py
@@ -1474,6 +1474,32 @@ class SQLiteDialect(default.DefaultDialect):
         return unique_constraints
 
     @reflection.cache
+    def get_check_constraints(self, connection, table_name,
+                              schema=None, **kw):
+        table_data = self._get_table_sql(
+            connection, table_name, schema=schema, **kw)
+        if not table_data:
+            return []
+
+        CHECK_PATTERN = (
+            '(?:CONSTRAINT (\w+) +)?'
+            'CHECK *\( *(.+) *\),? *'
+        )
+        check_constraints = []
+        # NOTE: we aren't using re.S here because we actually are
+        # taking advantage of each CHECK constraint being all on one
+        # line in the table definition in order to delineate.  This
+        # necessarily makes assumptions as to how the CREATE TABLE
+        # was emitted.
+        for match in re.finditer(CHECK_PATTERN, table_data, re.I):
+            check_constraints.append({
+                'sqltext': match.group(2),
+                'name': match.group(1)
+            })
+
+        return check_constraints
+
+    @reflection.cache
     def get_indexes(self, connection, table_name, schema=None, **kw):
         pragma_indexes = self._get_table_pragma(
             connection, "index_list", table_name, schema=schema)