Implement BaseModel class, TimestampMixin, TzDateTime type; cleanup Task model

tofu_api/common/database/metadata.py

@@ -0,0 +1,25 @@
+from sqlalchemy import MetaData as _MetaData
+
+__all__ = [
+    'MetaData',
+]
+
+
+class MetaData(_MetaData):
+    """
+    App specific subclass of the SQLAlchemy MetaData class.
+    """
+
+    # Define naming convention for constraints
+    _naming_convention = {
+        "ix": 'ix_%(column_0_label)s',
+        "uq": "uq_%(table_name)s_%(column_0_name)s",
+        "ck": "ck_%(table_name)s_%(constraint_name)s",
+        "fk": "fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s",
+        "pk": "pk_%(table_name)s"
+    }
+
+    def __init__(self, *args, naming_convention=None, **kwargs):
+        if not naming_convention:
+            naming_convention = self._naming_convention
+        super().__init__(*args, naming_convention=naming_convention, **kwargs)