Flask Web开发5.8:AttributeError: 'InstrumentedList' object has no attribute 'order

今天继续学习 Flask Web开发5.8节，在python console中输入：

user_role.users.order_by(User.username).all()

显示错误信息：

AttributeError: 'InstrumentedList' object has no attribute 'order_by'

 

我的hello.py

 

import os

 

from flask import Flask, render_template, session, redirect, url_for, flash
from flask_bootstrap import Bootstrap
from flask_moment import Moment
from flask_wtf import FlaskForm
from wtforms import StringField, SubmitField
from wtforms.validators import DataRequired
from flask_sqlalchemy import SQLAlchemy

 

basedir = os.path.abspath(os.path.dirname(__file__))
app = Flask(__name__)
app.config['SECRET_KEY'] = 'hard to guess string'

 

app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///' + os.path.join(basedir, 'data.sqlite')
app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN'] = True
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False

 

bootstrap = Bootstrap(app)
moment = Moment(app)
db = SQLAlchemy(app)

 

class Role(db.Model):
    __tablename__ = 'roles'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), unique=True)
    users = db.relationship('User', backref='role', lazy='dynamic')

 

    def __repr__(self):
        return '<Role %r>' % self.name

 

class User(db.Model):
    __tablename__ = 'users'
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(64), unique=True, index=True)
    role_id = db.Column(db.Integer, db.ForeignKey('roles.id'))

 

    def __repr__(self):
        return '<User %r>' % self.username

 

class NameForm(FlaskForm):
    name = StringField('What is your name?', validators=[DataRequired()])
    submit = SubmitField('Submit')

 

@app.errorhandler(404)
def page_not_found(e):
    return render_template('404.html'), 404

 

@app.errorhandler(500)
def internal_server_error(e):
    return render_template('500.html'), 500

 

@app.route('/', methods=['GET', 'POST'])
def index():
    form = NameForm()
    if form.validate_on_submit():
        old_name = session.get('name')
        if old_name is not None and old_name != form.name.data:
            flash('Looks like you have changed your name!')
        session['name'] = form.name.data
        return redirect(url_for('index'))
    return render_template('index.html', form=form, name=session.get('name'))

 

if __name__ == '__main__':
    app.run(debug=True)

 

 

最后的解决方法是：

将服务重启，重新在python console中重新加载数据，最后成功！