fix: Implement NOTYPE.python_type to fix adapting column types (#238)

Closes #237

Author: edgarrmondragon

target_postgres/connector.py

@@ -1,4 +1,5 @@
 """Handles Postgres interactions."""
+
 from __future__ import annotations
 
 import atexit
@@ -813,3 +814,12 @@ def process_bind_param(self, value, dialect):
         if value is not None and isinstance(value, (dict, list)):
             value = simplejson.dumps(value, use_decimal=True)
         return value
+
+    @property
+    def python_type(self):
+        """Return the Python type for this column."""
+        return object
+
+    def as_generic(self, *args: t.Any, **kwargs: t.Any):
+        """Return the generic type for this column."""
+        return TEXT()

target_postgres/sinks.py

@@ -115,7 +115,7 @@ def generate_temp_table_name(self):
         # exceeds maximum length of 63 characters
         # Is hit if we have a long table name, there is no limit on Temporary tables
         # in postgres, used a guid just in case we are using the same session
-        return f"{str(uuid.uuid4()).replace('-','_')}"
+        return f"{str(uuid.uuid4()).replace('-', '_')}"
 
     def bulk_insert_records(  # type: ignore[override]
         self,

target_postgres/tests/test_types.py

@@ -0,0 +1,38 @@
+"""Test custom types and the type hierarchy."""
+
+import pytest
+from sqlalchemy import Boolean, DateTime, Integer, String
+
+from target_postgres.connector import NOTYPE, PostgresConnector
+
+
+@pytest.fixture
+def connector():
+    """Create a PostgresConnector instance."""
+    return PostgresConnector(
+        config={
+            "dialect+driver": "postgresql+psycopg2",
+            "host": "localhost",
+            "port": "5432",
+            "user": "postgres",
+            "password": "postgres",
+            "database": "postgres",
+            "ssl_enable": False,
+            "ssl_client_certificate_enable": False,
+        },
+    )
+
+
+@pytest.mark.parametrize(
+    ("types", "expected"),
+    [
+        pytest.param([Integer(), String()], String, id="int+str=str"),
+        pytest.param([Boolean(), String()], String, id="bool+str=str"),
+        pytest.param([Integer(), DateTime()], Integer, id="int+datetime=int"),
+        pytest.param([NOTYPE(), String()], String, id="none+str=str"),
+        pytest.param([NOTYPE(), Integer()], NOTYPE, id="none+int=none"),
+    ],
+)
+def test_type_hierarchy(connector, types, expected):
+    """Test that types are merged correctly."""
+    assert type(connector.merge_sql_types(types)) is expected