distinct doesn't work as a column wrapper - no label is given

[banuni]

Environment details

• OS type and version: macOs 11.4
• Python version: Python 3.9
• pybigquery 0.9.0 (also tested on 0.8.0)

Steps to reproduce

make a query that uses sqlalchemy.distinct and not Query.distinct
EDIT: found out that the problem is that the former does not add an AS to the query, hence - adding a label manually is a workaround

Code example

  # this raises an error
  from sqlalchemy import distinct
  db.query(distinct(MyTable.my_column)).all()
  
  # this plays fine:
  db.query(MyTable.my_column).distinct().all()
  
  #edit: this ALSO plays nice
  from sqlalchemy import distinct
  db.query(distinct(MyTable.my_column).label('just_a_random_label').all()

Stack trace

Error on request:
Traceback (most recent call last):
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/engine/cursor.py", line 639, in _index_for_key
    rec = self._keymap[key]
KeyError: <sqlalchemy.sql.elements.UnaryExpression object at 0x12e0b9760>

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/some/path/.venv/lib/python3.9/site-packages/werkzeug/serving.py", line 319, in run_wsgi
    execute(self.server.app)
  File "/Users/some/path/.venv/lib/python3.9/site-packages/werkzeug/serving.py", line 308, in execute
    application_iter = app(environ, start_response)
  File "/Users/some/path/.venv/lib/python3.9/site-packages/flask/app.py", line 2088, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Users/some/path/.venv/lib/python3.9/site-packages/flask/app.py", line 2073, in wsgi_app
    response = self.handle_exception(e)
  File "/Users/some/path/.venv/lib/python3.9/site-packages/flask/app.py", line 2070, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/some/path/.venv/lib/python3.9/site-packages/flask/app.py", line 1515, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/some/path/.venv/lib/python3.9/site-packages/flask/app.py", line 1513, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/some/path/.venv/lib/python3.9/site-packages/flask/app.py", line 1499, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)
  File "/Users/some/path/app/my_file.py", line 666, in my_function()
    industries = get_db_session().query(distinct(MyTable.column)).all()
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/orm/query.py", line 2699, in all
    return self._iter().all()
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/orm/query.py", line 2834, in _iter
    result = self.session.execute(
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/orm/session.py", line 1680, in execute
    result = compile_state_cls.orm_setup_cursor_result(
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/orm/context.py", line 318, in orm_setup_cursor_result
    return loading.instances(result, querycontext)
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/orm/loading.py", line 88, in instances
    cursor.close()
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/util/langhelpers.py", line 70, in __exit__
    compat.raise_(
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/util/compat.py", line 207, in raise_
    raise exception
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/orm/loading.py", line 68, in instances
    *[
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/orm/loading.py", line 69, in <listcomp>
    query_entity.row_processor(context, cursor)
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/orm/context.py", line 2597, in row_processor
    getter = result._getter(column)
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/engine/result.py", line 881, in _getter
    return self._metadata._getter(key, raiseerr)
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/engine/result.py", line 98, in _getter
    index = self._index_for_key(key, raiseerr)
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/engine/cursor.py", line 641, in _index_for_key
    rec = self._key_fallback(key, ke, raiseerr)
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/engine/cursor.py", line 783, in _key_fallback
    util.raise_(
  File "/Users/some/path/.venv/lib/python3.9/site-packages/sqlalchemy/util/compat.py", line 207, in raise_
    raise exception
sqlalchemy.exc.NoSuchColumnError: "Could not locate column in row for column 'DISTINCT my_table.my_column'"

Making sure to follow these steps will guarantee the quickest resolution possible.

Thanks!