Flask decorator：无法从URL传递参数 [英] Flask decorator : Can't pass a parameter from URL

问题描述

我对瓶子很新，我正在尝试使用装饰者的潜力：p
我读了很多东西，发现了大量关于python装饰器的主题，但没有什么实际的帮助。 >

i'm quite new with flask and i'm trying to use the migthy power of decorators :p I read lot of things and found tons of topics about python decorators here but nothing really helpful.

@app.route('groups/<id_group>')
@group_required(id_group)
@login_required
def groups_groupIndex(id_group):
    #do some stuff
    return render_template('index_group.html')

这是我得到的错误：

This is the error i get :

@group_required(id_group), NameError: name 'id_group' is not defined

好的，id_group尚未定义，但我不明白为什么我可以在函数groups_groupIndex中使用id_group参数，但不能在装饰器中使用！

Ok, id_group is not defined yet, but I don't understand why i CAN use the id_group parameter from the URL in the function groups_groupIndex but NOT in the decorator!

我尝试移动/切换装饰器，但每次都发生相同的错误。

I try to move/switch decorators, but the same error occure each time.

这是我的装饰器，但它似乎工作正常

Here is my decorator, but it seems to work fine

def group_required(group_id):
    def decorated(func):
        @wraps(func)
        def inner (*args, **kwargs):
            #Core_usergroup : table to match users and groups
            groups = Core_usergroup.query.filter_by(user_id = g.user.id).all()
            for group in groups:
                #if the current user is in the group : return func
                if int(group.group_id) == int(group_id) :
                    return func(*args, **kwargs)
            flash(gettext('You have no right on this group'))
            return render_template('access_denied.html')     
        return inner
    return decorated

也许我没有看到像我应该装饰者...我可以使用我的装饰这种方式或需要我重写不同的东西？

Maybe i don't see decorators like i should... Can i use my decorator this way or need i rewrite something different ?

推荐答案

您将 group_id 定义为函数参数;这使得它成为该函数中的本地名称。

You defined group_id as a function parameter; that makes it a local name in that function.

这不会使名称可用于其他作用域;装饰器所在的全局名称空间看不到该名称。

That doesn't make the name available to other scopes; the global namespace that the decorator lives in cannot see that name.

然而， wrapper 函数可以。在调用时，它将从 @ apps.route（）包装器中传递该参数：

The wrapper function, however, can. It'll be passed that parameter from the @apps.route() wrapper when called:

def group_required():
    @wraps(func)
    def wrapper(group_id, *args, **kwargs):
        #Core_usergroup : table to match users and groups
        groups = Core_usergroup.query.filter_by(user_id = g.user.id).all()
        for group in groups:
            #if the current user is in the group : return func
            if int(group.group_id) == int(group_id) :
                return func(*args, **kwargs)
        flash(gettext('You have no right on this group'))
        return render_template('access_denied.html')     
    return wrapper

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