postgresql.py 文件源码

def get_or_create(session, model, defaults=None, **kwargs):
    """
        Generic method to get or create a SQLalchemy object from database
    """
    if defaults is None:
        defaults = {}
    try:
        query = session.query(model).filter_by(**kwargs)
        instance = query.first()
        if instance:
            return instance, False
        else:
            session.begin(nested=True)
            try:
                params = dict((k, v) for k, v in kwargs.items() if not isinstance(v, ClauseElement))
                params.update(defaults)
                instance = model(**params)
                session.add(instance)
                session.commit()
                return instance, True
            except IntegrityError as e:
                session.rollback()
                instance = query.one()
                return instance, False
    except Exception as e:
        raise e