Merge pull request #212 from datafold/aug18

Various fixes (issue #211, #208)

Author: erezsh

data_diff/__init__.py

@@ -41,11 +41,11 @@ def diff_tables(
     table2: TableSegment,
     *,
     # Name of the key column, which uniquely identifies each row (usually id)
-    key_column: str = "id",
+    key_column: str = None,
     # Name of updated column, which signals that rows changed (usually updated_at or last_update)
     update_column: str = None,
     # Extra columns to compare
-    extra_columns: Tuple[str, ...] = (),
+    extra_columns: Tuple[str, ...] = None,
     # Start/end key_column values, used to restrict the segment
     min_key: DbKey = None,
     max_key: DbKey = None,
@@ -73,18 +73,17 @@ def diff_tables(
 
     """
     tables = [table1, table2]
-    segments = [
-        t.new(
+    override_attrs = {k:v for k,v in dict(
             key_column=key_column,
             update_column=update_column,
             extra_columns=extra_columns,
             min_key=min_key,
             max_key=max_key,
             min_update=min_update,
             max_update=max_update,
-        )
-        for t in tables
-    ]
+    ).items() if v is not None}
+
+    segments = [t.new(**override_attrs) for t in tables] if override_attrs else tables
 
     differ = TableDiffer(
         bisection_factor=bisection_factor,

data_diff/databases/mysql.py

@@ -47,7 +47,7 @@ def create_connection(self):
             elif e.errno == mysql.errorcode.ER_BAD_DB_ERROR:
                 raise ConnectError("Database does not exist") from e
             else:
-                raise ConnectError(*e) from e
+                raise ConnectError(*e.args) from e
 
     def quote(self, s: str):
         return f"`{s}`"