SQLAlchemy 表类没有属性列

Question

我正在尝试动态访问使用 SQL Alchemy 创建的表的列列表。我创建了这样的表：

base.py

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import scoped_session, sessionmaker
import os

# Create database engine
db_name = 'database.db'
db_path = os.path.join(os.path.dirname(__file__), db_name)
db_uri = 'sqlite:///{}'.format(db_path)
engine = create_engine(db_uri, convert_unicode=True)

# Declarative base model to create database tables and classes
Base = declarative_base()
Base.metadata.bind = engine  # Bind engine to metadata of the base class

# Create database session object
db_session = scoped_session(sessionmaker(bind=engine, expire_on_commit=False))
Base.query = db_session.query_property()  # Used by graphql to execute queries

model_planet.py

from .base import Base
from .model_people import ModelPeople
from sqlalchemy import Column, Integer, String
from sqlalchemy.orm import relationship


class ModelPlanet(Base):
    """Planet model."""

    __tablename__ = 'planet'

    id = Column('id', Integer, primary_key=True)
    name = Column('name', String, doc="Name of the planet.")
    rotation_period = Column('rotation_period', String, doc="Rotation period of the planet.")
    orbital_period = Column('orbital_period', String, doc="Orbital period of the planet.")
    diameter = Column('diameter', String, doc="Diameter of the planet.")
    climate = Column('climate', String, doc="Climate period of the planet.")
    gravity = Column('gravity', String, doc="Gravity of the planet.")
    terrain = Column('terrain', String, doc="Terrain of the planet.")
    surface_water = Column('surface_water', String, doc="Surface water of the planet.")
    population = Column('population', String, doc="Population of the planet.")
    created = Column('created', String, doc="Record created date.")
    edited = Column('edited', String, doc="Record last updated date.")
    url = Column('url', String, doc="URL of the planet in the Star Wars API.")

    peopleList = relationship(ModelPeople, backref='planet')

在另一个文件中，我正在导入 model_planet.ModelPlanet 并尝试按照此处的文档访问其列：http://docs.sqlalchemy.org/en/latest/core/metadata.html

from database.model_planet import ModelPlanet

print(type(ModelPlanet))
for column in ModelPlanet.columns:
    print(column)

我得到以下信息：

<class 'sqlalchemy.ext.declarative.api.DeclarativeMeta'>
Traceback (most recent call last):
[...]
    for column in ModelPlanet.columns:
AttributeError: type object 'ModelPlanet' has no attribute 'columns'

我想这与我定义表格的方式有关。如何动态访问其列？

谢谢

Answer 1

您需要像这样获得访问权限：

for column in ModelPlanet.__table__.columns:
    print(column)