SQLAlchemy: Improve DDL compiler to ignore unique key constraints

Author: amotl

CHANGES.txt

@@ -13,7 +13,8 @@ Unreleased
   certificate details are immanent, like no longer accepting the long
   deprecated ``commonName`` attribute. Instead, going forward, only the
   ``subjectAltName`` attribute will be used.
-- SQLAlchemy: Improve DDL compiler to ignore foreign key constraints
+- SQLAlchemy: Improve DDL compiler to ignore foreign key and uniqueness
+  constraints
 
 .. _urllib3 v2.0 migration guide: https://urllib3.readthedocs.io/en/latest/v2-migration-guide.html
 .. _urllib3 v2.0 roadmap: https://urllib3.readthedocs.io/en/stable/v2-roadmap.html

src/crate/client/sqlalchemy/compiler.py

@@ -184,6 +184,13 @@ def visit_foreign_key_constraint(self, constraint, **kw):
         """
         return None
 
+    def visit_unique_constraint(self, constraint, **kw):
+        """
+        CrateDB does not support unique key constraints.
+        """
+        return None
+
+
 class CrateTypeCompiler(compiler.GenericTypeCompiler):
 
     def visit_string(self, type_, **kw):

src/crate/client/sqlalchemy/tests/compiler_test.py

@@ -346,3 +346,28 @@ class ItemStore(Base):
             )
 
         """))  # noqa: W291, W293
+
+    def test_ddl_with_unique_key(self):
+        """
+        Verify the CrateDB dialect properly ignores unique key constraints.
+        """
+
+        Base = sa.orm.declarative_base(metadata=self.metadata)
+
+        class FooBar(Base):
+            """The entity."""
+
+            __tablename__ = "foobar"
+
+            id = sa.Column(sa.Integer, primary_key=True)
+            name = sa.Column(sa.String, unique=True)
+
+        self.metadata.create_all(self.engine, tables=[FooBar.__table__], checkfirst=False)
+        self.assertEqual(self.executed_statement, dedent("""
+            CREATE TABLE testdrive.foobar (
+            \tid INT NOT NULL, 
+            \tname STRING, 
+            \tPRIMARY KEY (id)
+            )
+
+        """))  # noqa: W291