feat: Add function security option to postgres function.

src/sqlalchemy_declarative_extensions/dialects/postgresql/function.py

@@ -1,19 +1,29 @@
 from __future__ import annotations
 
+import enum
 import textwrap
 from dataclasses import dataclass, replace
 
 from sqlalchemy_declarative_extensions.function import base
 
 
+@enum.unique
+class FunctionSecurity(enum.Enum):
+    invoker = "INVOKER"
+    definer = "DEFINER"
+
+
 @dataclass
 class Function(base.Function):
     """Describes a PostgreSQL function.
 
     Many function attributes are not currently supported. Support is **currently**
-    minimal due to being a means to an end for defining triggers.
+    minimal due to being a means to an end for defining triggers, but can certainly
+    be evaluated/added on request.
     """
 
+    security: FunctionSecurity = FunctionSecurity.invoker
+
     @classmethod
     def from_unknown_function(cls, f: base.Function | Function) -> Function:
         if not isinstance(f, Function):
@@ -27,13 +37,39 @@ def from_unknown_function(cls, f: base.Function | Function) -> Function:
 
         return f
 
+    def to_sql_create(self, replace=False):
+        components = ["CREATE"]
+
+        if replace:
+            components.append("OR REPLACE")
+
+        components.append("FUNCTION")
+        components.append(self.qualified_name + "()")
+
+        if self.returns:
+            components.append(f"RETURNS {self.returns}")
+
+        if self.security == FunctionSecurity.definer:
+            components.append("SECURITY DEFINER")
+
+        components.append(f"LANGUAGE {self.language}")
+        components.append(f"AS $${self.definition}$$")
+
+        return " ".join(components) + ";"
+
     def normalize(self) -> Function:
         returns = self.returns.lower()
         definition = textwrap.dedent(self.definition)
         return replace(
             self, returns=type_map.get(returns, returns), definition=definition
         )
 
+    def with_security(self, security: FunctionSecurity):
+        return replace(self, security=security)
+
+    def with_security_definer(self):
+        return replace(self, security=FunctionSecurity.definer)
+
 
 type_map = {
     "bigint": "int8",

src/sqlalchemy_declarative_extensions/dialects/postgresql/query.py

@@ -10,7 +10,10 @@
     parse_acl,
     parse_default_acl,
 )
-from sqlalchemy_declarative_extensions.dialects.postgresql.function import Function
+from sqlalchemy_declarative_extensions.dialects.postgresql.function import (
+    Function,
+    FunctionSecurity,
+)
 from sqlalchemy_declarative_extensions.dialects.postgresql.role import Role
 from sqlalchemy_declarative_extensions.dialects.postgresql.schema import (
     default_acl_query,
@@ -165,6 +168,9 @@ def get_functions_postgresql(connection: Connection) -> list[Function]:
             returns=f.return_type,
             language=f.language,
             schema=f.schema if f.schema != "public" else None,
+            security=FunctionSecurity.definer
+            if f.security_definer
+            else FunctionSecurity.invoker,
         )
         functions.append(function)
     return functions

src/sqlalchemy_declarative_extensions/dialects/postgresql/schema.py

@@ -77,6 +77,7 @@
     column("pronamespace"),
     column("prolang"),
     column("prorettype"),
+    column("prosecdef"),
 )
 
 pg_language = table(
@@ -258,6 +259,7 @@ def _schema_not_pg(column=pg_namespace.c.nspname):
         pg_language.c.lanname.label("language"),
         pg_type.c.typname.label("return_type"),
         pg_proc.c.prosrc.label("source"),
+        pg_proc.c.prosecdef.label("security_definer"),
     )
     .select_from(
         pg_proc.join(pg_namespace, pg_proc.c.pronamespace == pg_namespace.c.oid)

src/sqlalchemy_declarative_extensions/function/base.py

@@ -31,28 +31,23 @@ def normalize(self) -> Function:
         raise NotImplementedError()  # pragma: no cover
 
     def to_sql_create(self, replace=False):
-        components = ["CREATE"]
-
-        if replace:
-            components.append("OR REPLACE")
-
-        components.append("FUNCTION")
-        components.append(self.qualified_name + "()")
-
-        if self.returns:
-            components.append(f"RETURNS {self.returns}")
-
-        components.append(f"LANGUAGE {self.language}")
-        components.append(f"AS $${self.definition}$$")
-
-        return " ".join(components) + ";"
+        raise NotImplementedError()
 
     def to_sql_update(self):
         return self.to_sql_create(replace=True)
 
     def to_sql_drop(self):
         return f"DROP FUNCTION {self.qualified_name}();"
 
+    def with_name(self, name: str):
+        return replace(self, name=name)
+
+    def with_language(self, language: str):
+        return replace(self, language=language)
+
+    def with_return_type(self, return_type: str):
+        return replace(self, returns=return_type)
+
 
 @dataclass
 class Functions:

tests/function/test_pg_security_definer.py

@@ -0,0 +1,105 @@
+import pytest
+from pytest_mock_resources import create_postgres_fixture
+from sqlalchemy import Column, text, types
+from sqlalchemy.exc import ProgrammingError
+
+from sqlalchemy_declarative_extensions import (
+    declarative_database,
+    register_function,
+    register_sqlalchemy_events,
+)
+from sqlalchemy_declarative_extensions.dialects.postgresql import Function
+from sqlalchemy_declarative_extensions.dialects.postgresql.grant import (
+    DefaultGrant,
+)
+from sqlalchemy_declarative_extensions.dialects.postgresql.role import Role
+from sqlalchemy_declarative_extensions.function.compare import compare_functions
+from sqlalchemy_declarative_extensions.grant.base import Grants
+from sqlalchemy_declarative_extensions.role.base import Roles
+from sqlalchemy_declarative_extensions.sqlalchemy import declarative_base
+
+_Base = declarative_base()
+
+
+@declarative_database
+class Base(_Base):  # type: ignore
+    __abstract__ = True
+
+    roles = Roles(ignore_unspecified=True).are(Role("can_insert"), Role("cant_insert"))
+    grants = Grants().are(
+        DefaultGrant.on_tables_in_schema("public").grant("select", to="cant_insert"),
+        DefaultGrant.on_tables_in_schema("public")
+        .grant("insert", to="cant_insert")
+        .invert(),
+        DefaultGrant.on_tables_in_schema("public").grant(
+            "insert", "select", to="can_insert"
+        ),
+    )
+
+
+class Foo(Base):
+    __tablename__ = "foo"
+
+    id = Column(types.Integer(), primary_key=True)
+
+
+function_invoker = (
+    Function(
+        "add_one_invoker",
+        """
+    DECLARE
+        m INTEGER;
+    BEGIN
+    SELECT coalesce(max(id), 0) + 1 INTO m FROM foo;
+    INSERT INTO foo (id) VALUES (m);
+    RETURN m;
+    END
+    """,
+    )
+    .with_return_type("INTEGER")
+    .with_language("plpgsql")
+)
+
+function_definer = function_invoker.with_security_definer().with_name("add_one_definer")
+
+register_function(Base.metadata, function_invoker)
+register_function(Base.metadata, function_definer)
+
+
+register_sqlalchemy_events(Base.metadata, roles=True, grants=True, functions=True)
+
+pg = create_postgres_fixture(engine_kwargs={"echo": True}, session=True)
+
+
+def test_function_security(pg):
+    Base.metadata.create_all(bind=pg.connection())
+    pg.commit()
+
+    # Permission decided by invoker
+    pg.execute(text("SET ROLE cant_insert"))
+    with pytest.raises(ProgrammingError) as e:
+        result = pg.execute(text("SELECT add_one_invoker()")).scalar()
+    assert "permission denied for table foo" in str(e)
+
+    pg.rollback()
+
+    pg.execute(text("SET ROLE can_insert"))
+    result = pg.execute(text("SELECT add_one_invoker()")).scalar()
+    assert result == 1
+
+    # Permission decided by definer
+    pg.execute(text("SET ROLE cant_insert"))
+    result = pg.execute(text("SELECT add_one_definer()")).scalar()
+    assert result == 2
+
+    pg.execute(text("SET ROLE can_insert"))
+    result = pg.execute(text("SELECT add_one_definer()")).scalar()
+    assert result == 3
+
+    # Just a double check
+    result = pg.query(Foo.id).count()
+    assert result == 3
+
+    connection = pg.connection()
+    diff = compare_functions(connection, Base.metadata.info["functions"], Base.metadata)
+    assert diff == []