用Python枚举定义SQLAlchemy枚举列会引发"ValueError:不是有效的枚举".

问题描述

我正在尝试遵循此示例在使用以下内容的表中具有枚举列Python的Enum类型.我定义了枚举，然后将其传递到示例中所示的列，但得到ValueError: <enum 'FruitType'> is not a valid Enum.如何使用Python枚举正确定义SQLAlchemy枚举列?

I am trying to follow this example to have an enum column in a table that uses Python's Enum type. I define the enum then pass it to the column as shown in the example, but I get ValueError: <enum 'FruitType'> is not a valid Enum. How do I correctly define a SQLAlchemy enum column with a Python enum?

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
import enum

app = Flask(__name__)
db = SQLAlchemy(app)

class FruitType(enum.Enum):
    APPLE = "Crunchy apple"
    BANANA = "Sweet banana"

class MyTable(db.Model):
    id = db.Column(db.Integer, primary_key = True)
    fruit_type = db.Column(enum.Enum(FruitType))

File "why.py", line 32, in <module>
    class MyTable(db.Model):
  File "why.py", line 34, in MyTable
    fruit_type = db.Column(enum.Enum(FruitType))
  File "/usr/lib/python2.7/dist-packages/enum/__init__.py", line 330, in __call__
    return cls.__new__(cls, value)
  File "/usr/lib/python2.7/dist-packages/enum/__init__.py", line 642, in __new__
    raise ValueError("%s is not a valid %s" % (value, cls.__name__))
ValueError: <enum 'FruitType'> is not a valid Enum

推荐答案

列类型应为 sqlalchemy.types.Enum .您将再次使用Python Enum类型，该类型对值有效，但对列类型无效.

The column type should be sqlalchemy.types.Enum. You're using the Python Enum type again, which is valid for the value but not the column type.

class MyTable(db.Model):
    id = db.Column(db.Integer, primary_key = True)
    fruit_type = db.Column(db.Enum(FruitType))

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