sqlalchemy中的查询枚举列导致LookupError

我的桌子有一种 contact_type :

                                        List of data types
 Schema |     Name      | Internal name | Size |   Elements    |  Owner   | Access privileges | Description
--------+---------------+---------------+------+---------------+----------+-------------------+-------------
 public | contact_types | contact_types | 4    | unknown      +| postgres |                   |
        |               |               |      | incoming_text+|          |                   |
        |               |               |      | incoming_call+|          |                   |
        |               |               |      | outgoing_call |          |                   |

在表格中:

  Table "public.calls"
    Column    |           Type           |                     Modifiers
--------------+--------------------------+----------------------------------------------------
 contact_type | contact_types            |

在python中,我创建了 enum 每 the docs :

import enum

class contact_types(enum.Enum):
    unknown: 1
    incoming_text: 2
    incoming_call: 3
    outgoing_call: 4

class Call(db.Model):
    contact_type = db.Column(db.Enum(contact_types))

一切看起来都很好。插入工作,我可以在查看表时看到值,但是SQLAlchemy的验证在查询时似乎不满意。这会导致错误:

calls = Call.query.order_by(Call.time.desc()).limit(pagesize).offset(offset)
for c in calls:
    print(c)

“未知”在枚举中。我是否缺少将查询连接到枚举类的步骤?