SQLAlchemy向我显示"AttributeError:类型对象'User'没有属性'columns'"; [英] SQLAlchemy show me that "AttributeError: type object 'User' has no attribute 'columns'"
问题描述
我正在使用python + Flask + SQLAlchemy构建一个小项目,我制作了以下模型文件:
I am building a small project use python+Flask+SQLAlchemy, I make a model file following:
################# start of models.py #####################
from sqlalchemy import Column, Integer, String, Sequence, Date, DateTime, ForeignKey
from sqlalchemy.orm import relationship, backref
from dk.database import Base
import datetime
class User(Base):
__tablename__ = 'users'
id = Column(Integer, Sequence('seq_user_id'), primary_key=True)
name = Column(String(50), unique=True, index = True, nullable = False)
email = Column(String(120), unique=True, index = True, nullable = False)
password = Column(String(128), nullable = False)
def __init__(self, name, email, password):
self.name = name
self.email = email
self.password = password
def __repr__(self):
return '<User %r>' % (self.name)
class Session(Base):
__tablename__ = 'session'
id = Column(String(128), primary_key = True, nullable = False)
user_name = Column(String(30), nullable = False)
user_id = Column(Integer, ForeignKey('users.id'))
user = relationship('User', backref=backref('session', lazy='dynamic'))
def __repr__(self):
return '<Session %r>' % (self.id)
################# end of models.py #####################
然后我建立一个初始文件:
and I build a initial file following:
################# start of __init__.py #################
from flask import Flask
from flask.ext.sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config.from_object('config') #load database config information
db = SQLAlchemy(app)
################# end of __init__.py #################
当我在脚本中运行"init_db()"时,成功建立到数据库的表. 但是当我想查看SQL脚本时,我在脚本中运行了"print CreateTable(User)",系统显示以下错误:
when I run the "init_db()" in script, tables built to database successful. but when I want to see the SQL script then I run the "print CreateTable(User)" in script, the system show follwing errors:
File "/home/jacky/flaskcode/venv/lib/python2.6/site-packages/sqlalchemy/schema.py", line 3361, in __init__
for column in element.columns
AttributeError: type object 'User' has no attribute 'columns'
我不知道如何解决这个问题!
I have no idea how to solve this problem!
推荐答案
您需要为CreateTable()
传递 Table
对象:
You need to pass in a Table
object for CreateTable()
:
CreateTable(User.__table__)
但是如果您想查看SQLAlchemy发出的SQL语句,最好通过设置
but if you wanted to see the SQL statements that SQLAlchemy issues you are better off switching on echoing by setting echo=True
when creating the connection.
Flask SQLAlchemy集成层支持 SQLALCHEMY_ECHO
选项设置该标志.
The Flask SQLAlchemy integration layer supports a SQLALCHEMY_ECHO
option to set that flag.
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