在Python中错误使用全局变量？

Question

我的全局变量返回的值不一致。我将感谢您的指导。

我有一个列表屏幕，可以按用户名，姓氏或姓氏的顺序排列。通过分页，它将一次列出几个，然后我可以翻页/下一页或翻页/首页。如果我从一个标准更改为另一个标准，则它将直接转到列表的第1页，否则它将根据需要提供下一个/最后一个/上一个/第一个。为了让页面记住顺序（用户名/姓氏/姓氏），我将其保存在全局变量member_filter_criteria中。

在我的PC上，此代码可以很好地与下面的代码配合使用，当我上传到Heroku时，member_filter_criteria值会在页面之间随机变化。您可以在运行的应用程序中看到这一点：首先在https://clubmanager-2020ad.herokuapp.com/auth/login?next=%2Findex上以Janice（密码“ cat”）登录，然后输入https://clubmanager-2020ad.herokuapp.com/testmembers。

我怀疑我使用或引用的全局参数不正确，但是有人可以告诉我正确的方法吗？

相关代码：

1）我的routes.py文件的顶部，紧随导入之后

...

member_filter_criteria = "Surname"
like = '%'
....

2 route.py中的def是：

@bp.route('/testmembers/', methods=['GET', 'POST'])
@login_required
def testmembers():
    # I need to retrieve the value of member_filter_criteria and like from the last call to this def
    #  This is why I have declared them as global

    global member_filter_criteria
    global like

    def printC(answer):
        return "\n{:0.2f}.\n".format(answer)

    form = MemberForm()
    form.fieldtype.choices = [('--', '--'), ('User Name', 'User Name'), ('Forename', 'Forename'),
                              ('Surname', 'Surname')]
    user = Users.query.filter_by(username=current_user.username).first_or_404()
    strbal = printC(user.balance / 100)
    club = Club.query.filter_by(clubnum=current_user.club).first_or_404()
    clubname = club.clubname
    todaydate = date.today()

    # If a new query we must set the pagination page to 1 at the end of this def
    #   Otherwise we use the current page number
    newquery = 'No'
    if form.validate_on_submit():
        newquery = 'Yes'
        like = form.searchletter.data.upper() + '%'
        if form.fieldtype.data == 'User Name':
            member_filter_criteria = 'User Name'
            users_list = Users.query.filter_by(club=club.clubnum).filter(Users.username.like(like)).order_by(
                Users.username.asc())
        if form.fieldtype.data == 'Forename':
            member_filter_criteria = 'Forename'
            users_list = Users.query.filter_by(club=club.clubnum).filter(Users.forename.like(like)).order_by(
                Users.forename.asc())
        if form.fieldtype.data == 'Surname':
            member_filter_criteria = 'Surname'
            users_list = Users.query.filter_by(club=club.clubnum).filter(Users.surname.like(like)).order_by(
                Users.surname.asc(), Users.forename.asc())

        if form.fieldtype.data == '--':
            users_list = Users.query.filter_by(club=club.clubnum).filter(Users.forename.like(like)) \
                .order_by(Users.surname.asc(), Users.forename.asc())
    else:
        form.fieldtype.data = member_filter_criteria
        if like == '%%':
            like = '%'
        form.searchletter.data = like
        if member_filter_criteria == '':
            users_list = Users.query.filter_by(club=club.clubnum).order_by(Users.surname.asc(), Users.forename.asc())
        if member_filter_criteria == 'User Name':
            users_list = Users.query.filter_by(club=club.clubnum).filter(Users.username.like(like)).order_by(
                Users.username.asc())
        if member_filter_criteria == 'Forename':
            users_list = Users.query.filter_by(club=club.clubnum).filter(Users.forename.like(like)).order_by(
                Users.forename.asc())
        if member_filter_criteria == 'Surname':
            users_list = Users.query.filter_by(club=club.clubnum).filter(Users.surname.like(like)).order_by(
                Users.surname.asc(),
                Users.forename.asc())
        if member_filter_criteria == '--':
            users_list = Users.query.filter_by(club=club.clubnum).filter(Users.forename.like(like)) \
                .order_by(Users.surname.asc(), Users.forename.asc())

    paginator = Paginator(users_list, club.items_per_page)
    if newquery == 'Yes':
        page = 1
    else:
        page = request.args.get('page', type=int)

    paginatelist = paginator.get_page(page)
    return render_template('member.html', title=_('Members'),
                           club=club, paginator=paginator, paginatelist=paginatelist,
                           form=form)

3forms.py中的表单（更改过滤器标准是：）>

class MemberForm(FlaskForm):
    searchletter = StringField(_l('Choose One or more letters of name') )
    fieldtype = SelectField(_l('Search on: User Name<br>User Forename<br>User Surname'))
    submit = SubmitField(_l('Submit'))
4 HTML屏幕是：

{% extends "base.html" %}
{% import 'bootstrap/wtf.html' as wtf %}

{% block app_content %}
    <h1>{{ _('Member details')}} </h1>
    {% if current_user.adminuser == 'Yes' or current_user.coach == 'Yes' or
      current_user.treasurer == 'Yes' or current_user.sessionmanager ==  'Yes' %}
      {% if form %}
        {{ wtf.quick_form(form) }}
      <br>
      {% endif %}
    {% endif %}
<table class="table table-hover">
        <tr>
        <th>Username</th>
        <th>User Number</th>
        <th>Forename</th>
        <th>Surname</th>
        <th>Member Type</th>
        <th>Balance</th>
        <th>Current<br>Member</th>
        <th>Member<br>Expires</th>
        <th>Registered<br>Member</th>

   <!--     <th>Administrator</th>
        <th>Coach</th>
        <th>Activity <br> Manager</th>
        <th>Treasurer</th> -->
        </tr>
    {% for user in paginatelist %}
        {% include '_user.html' %}
    {% endfor %}
    {% include '_paginate.html' %}

</table>
    {% include '_paginate.html' %}

{% endblock %}

我的全局变量返回的值不一致。我将不胜感激。我有一个列表屏幕，可以按用户名，姓氏或姓氏的顺序排列。通过分页将...

Answer 1

Grismar向我指出了正确的方向-不要在Web应用程序中使用Global变量，因为它们是无状态的，而且不可能知道哪个线程将接收请求。