Flask 装饰器不能很好地协同工作

Question

我正在尝试在测试 Flask 应用程序中使用蓝图，但我运行遇到了一个奇怪的问题。这是我的代码的相关部分：

from functools import wraps
from flask import flash, redirect, render_template, \
request, session, url_for, Blueprint
from sqlalchemy.exc import IntegrityError
from datetime import datetime
from time import localtime, strftime

from .forms import AddAppointmentForm
from project import db
from project.models import Appointment

appointments_blueprint = Blueprint('appointments', __name__)

def login_required(test):
    @wraps(test)
    def wrap(*args, **kwargs):
        if 'logged_in' in session:
            return test(*args, **kwargs)
        else:
            flash('You need to login first.')
            return redirect(url_for('users.login'))
        return wrap

@appointments_blueprint.route('/appointments/')
@login_required
def appointments():
    # Get current date
    current_datetime = strftime("%Y-%m-%d %H:%M:%S", localtime())
    future_appointments = db.session.query(Appointment)\
        .filter(Appointment.due_date >= current_datetime)\
        .order_by(Appointment.due_date.asc())
    past_appointments = db.session.query(Appointment)\
        .filter(Appointment.due_date < current_datetime)\
        .order_by(Appointment.due_date.asc())
    return render_template('appointments.html',
        form = AddAppointmentForm(request.form),
        future_appointments=future_appointments,
        past_appointments=past_appointments)

现在，当我运行应用程序时，出现此错误：

  File "/home/mosquito/git/flask-scheduler/project/appointments/views.py", line 72, in <module>
    @login_required
  File "/home/mosquito/python_envs/flask-scheduler/local/lib/python2.7/site-packages/flask/blueprints.py", line 160, in decorator
    endpoint = options.pop("endpoint", f.__name__)
AttributeError: 'NoneType' object has no attribute '__name__'

查看 blueprints.py，我看到了这个：

def route(self, rule, **options):
    """Like :meth:`Flask.route` but for a blueprint.  The endpoint for the
    :func:`url_for` function is prefixed with the name of the blueprint.
    """
    def decorator(f):
        endpoint = options.pop("endpoint", f.__name__)
        self.add_url_rule(rule, endpoint, f, **options)
        return f
    return decorator

这失败了，因为 'f' 是 None。现在更有趣了，如果我删除

@login_required

decorator，到了那个点，f是一个函数，就OK了。

另一方面，如果我删除

@appointments_blueprint.route()

装饰器，它也可以。所以看起来这两个装饰器的组合导致 f 成为 None...知道这里发生了什么吗？

Answer 1

您需要取消缩进 return 行：

def login_required(test):
    @wraps(test)
    def wrap(*args, **kwargs):
        if 'logged_in' in session:
            return test(*args, **kwargs)
        else:
            flash('You need to login first.')
            return redirect(url_for('users.login'))
    return wrap

你把它变成了 wrap 函数本身的一部分，所以外部装饰器函数没有返回任何东西。

删除 @appointments_blueprint.route() 根本不会注册路由，因此您永远不会发现您将 appointments 设置为 None。

Flask 装饰器不能很好地协同工作

Flask decorators not working together nicely

python

flask

decorator

python-decorators