Merge pull request #232 from ydb-platform/fix-sqlalchemy-nullable

Fix sqlalchemy nullable

Author: Valeria1235

examples/_sqlalchemy_example/example.py

@@ -196,7 +196,7 @@ def run_example_core(engine):
 def main():
     parser = argparse.ArgumentParser(
         formatter_class=argparse.RawDescriptionHelpFormatter,
-        description="""\033[92mYandex.Database examples _sqlalchemy usage.\x1b[0m\n""",
+        description="""\033[92mYandex.Database examples sqlalchemy usage.\x1b[0m\n""",
     )
     parser.add_argument(
         "-d",

tests/_sqlalchemy/_test_inspect.py

@@ -0,0 +1,24 @@
+import ydb
+
+import sqlalchemy as sa
+
+
+def test_get_columns(driver_sync, engine):
+    session = ydb.retry_operation_sync(
+        lambda: driver_sync.table_client.session().create()
+    )
+    session.execute_scheme(
+        "CREATE TABLE test(id Int64 NOT NULL, value TEXT, num DECIMAL(22, 9), PRIMARY KEY (id))"
+    )
+    inspect = sa.inspect(engine)
+    columns = inspect.get_columns("test")
+    for c in columns:
+        c["type"] = type(c["type"])
+
+    assert columns == [
+        {"name": "id", "type": sa.INTEGER, "nullable": False},
+        {"name": "value", "type": sa.TEXT, "nullable": True},
+        {"name": "num", "type": sa.DECIMAL, "nullable": True},
+    ]
+
+    session.execute_scheme("DROP TABLE test")

ydb/_sqlalchemy/__init__.py

@@ -206,14 +206,16 @@ def upsert(table):
 }
 
 
-def _get_column_type(t):
+def _get_column_info(t):
+    nullable = False
     if isinstance(t, ydb.OptionalType):
+        nullable = True
         t = t.item
 
     if isinstance(t, ydb.DecimalType):
-        return sa.DECIMAL(precision=t.item.precision, scale=t.item.scale)
+        return sa.DECIMAL(precision=t.precision, scale=t.scale), nullable
 
-    return COLUMN_TYPES[t]
+    return COLUMN_TYPES[t], nullable
 
 
 class YqlDialect(DefaultDialect):
@@ -268,11 +270,12 @@ def get_columns(self, connection, table_name, schema=None, **kw):
         columns = raw_conn.describe(qt)
         as_compatible = []
         for column in columns:
+            col_type, nullable = _get_column_info(column.type)
             as_compatible.append(
                 {
                     "name": column.name,
-                    "type": _get_column_type(column.type),
-                    "nullable": True,
+                    "type": col_type,
+                    "nullable": nullable,
                 }
             )