Support Sequence

[matemax]

HI, i am using Sequence in my models.

SEQUENCE = Sequence('my_sequence', start=1)

class MyTabel(Base):

    __tablename__ = 'tabel_1'
    Base.metadata = metadata

    id_2 = Column(String(36), ForeignKey('tabel_2.id_2 ', ondelete='CASCADE'), primary_key=True)

    id_1 = Column(String(36), ForeignKey('tabel_2.id_1 ', ondelete='CASCADE'), primary_key=True)

    seq_id= Column(Integer,  SEQUENCE )

And when i try insert into the table with sequence a new value i have following error:

  File "C:\Program Files\Python37\lib\site-packages\asyncpg\connection.py", line 433, in fetchval
    data = await self._execute(query, args, 1, timeout)
  File "C:\Program Files\Python37\lib\site-packages\asyncpgsa\connection.py", line 89, in _execute
    query, compiled_args = compile_query(query, dialect=self._dialect)
  File "C:\Program Files\Python37\lib\site-packages\asyncpgsa\connection.py", line 64, in compile_query
    query = execute_defaults(query)  # default values for Insert/Update
  File "C:\Program Files\Python37\lib\site-packages\asyncpgsa\connection.py", line 40, in execute_defaults
    _execute_default_attr(query, query.parameters, attr_name)
  File "C:\Program Files\Python37\lib\site-packages\asyncpgsa\connection.py", line 48, in _execute_default_attr
    if attr.is_scalar:
AttributeError: 'Sequence' object has no attribute 'is_scalar'

Following change fix it in my case. But i am not sure that is correct.

# old
def _execute_default_attr(query, param, attr_name):
    for col in query.table.columns:
        attr = getattr(col, attr_name)
        if attr and param.get(col.name) is None:
            if attr.is_scalar:
                param[col.name] = attr.arg
            elif attr.is_callable:
                param[col.name] = attr.arg({})

# new
def _execute_default_attr(query, param, attr_name):
    for col in query.table.columns:
        attr = getattr(col, attr_name)
        if attr and param.get(col.name) is None:
            if attr.is_sequence:
                continue
            if attr.is_scalar:
                param[col.name] = attr.arg
            elif attr.is_callable:
                param[col.name] = attr.arg({})

asyncpgsa - Version: 0.25.2
sqlalchemy - Version: 1.2.15

[nhumrich]

Sweet. Sorry I am getting so late to this. If you would like to open up a pull request, requesting this change, with a couple tests, I would be happy to review it and likely merge it in.