Python全局变量在Apache中不起作用

Question

我遇到了一个关于全局变量的问题。在Django的开发服务器上运行时一切正常，但在Apache服务器上就不行了。

下面是我的代码：

red= "/project3/test/"


def showAddRecipe(request):
    #global objc
    if "userid" in request.session:
        objc["ErrorMsgURL"]= ""
        try:
            urlList= request.POST
            URL= str(urlList['url'])
            URL= URL.strip('http://')
            URL= "http://" + URL

            recipe= __addRecipeUrl__(URL)

            if (recipe == 'FailToOpenURL') or (recipe == 'Invalid-website-URL'):
                #request.session["ErrorMsgURL"]= "Kindly check URL, Please enter a valid URL"
                objc["ErrorMsgURL"]= "Kindly check URL, Please enter a valid URL"
                print "here global_context =", objc
                arurl= HttpResponseRedirect("/project3/add/import/")
                arurl['ErrorMsgURL']= objc["ErrorMsgURL"]
                #return HttpResponseRedirect("/project3/add/import/")
                #return render_to_response('addRecipeUrl.html', objc, context_instance = RequestContext(request))
                return (arurl)
            else:
                objc["recipe"] = recipe
                return render_to_response('addRecipe.html',
                    objc,
                    context_instance = RequestContext(request))
        except:
            objc["recipe"] = ""
            return render_to_response('addRecipe.html',
                objc,
                context_instance = RequestContext(request))
    else:
        global red
        red= "/project3/add/"
        return HttpResponseRedirect("/project3/login")



def showAddRecipeUrl(request):
    if "userid" in request.session:
        return render_to_response('addRecipeUrl.html',
            objc, 
            context_instance = RequestContext(request))
    else:
        global red
        red= "/project3/add/import/"
        return HttpResponseRedirect("/project3/login")


def showLogin(request):
    obj = {}
    obj["error_message"] = ""
    obj["registered"] = ""

    if request.method == "POST":
        if (red == "/project3/test"):
            next= '/project3/recipes'
        else:
            next= red

        try:
            username = request.POST['username']
            password = request.POST['password']
            user = authenticate(username=username, password=password)
        except:
            user = authenticate(request=request)

        if user is not None:
            if user.is_active:
                login(request, user)
                request.session["userid"] = user.id

                # Redirect to a success page.
                return HttpResponseRedirect(next)

这段代码在Django开发服务器上运行没问题，但在Apache上，网址却被重定向到了'/project3/recipes'。

Answer 1

之前已经告诉过你，在像Apache这样的多进程环境中使用全局对象是非常危险的。因为会有多个用户同时访问彼此的变量，这样是无法正常工作的。

extraneon说得对，你应该使用会话（sessions）来解决这个问题——这就是会话的用途。从你对他回答的评论来看，很明显你没有阅读过会话文档——你现在应该去看看。

Answer 2

大家好，谢谢你们的帮助。是的，我知道使用全局变量不是正确的方法，但我之前没能让它正常工作。不过现在它可以正常运行了，下面是代码：

def showAddRecipe(request):
    #global objc
    if "userid" in request.session:
        objc["ErrorMsgURL"]= ""
        try:
            urlList= request.POST
            URL= str(urlList['url'])
            URL= URL.strip('http://')
            URL= "http://" + URL

            recipe= __addRecipeUrl__(URL)

            if (recipe == 'FailToOpenURL') or (recipe == 'Invalid-website-URL'):
                #request.session["ErrorMsgURL"]= "Kindly check URL, Please enter a valid URL"
                objc["ErrorMsgURL"]= "Kindly check URL, Please enter a valid URL"
                print "here global_context =", objc
                arurl= HttpResponseRedirect("/project3/add/import/")
                arurl['ErrorMsgURL']= objc["ErrorMsgURL"]
                #return HttpResponseRedirect("/project3/add/import/")
                #return render_to_response('addRecipeUrl.html', objc, context_instance = RequestContext(request))
                return (arurl)
            else:
                objc["recipe"] = recipe
                return render_to_response('addRecipe.html',
                    objc,
                    context_instance = RequestContext(request))
        except:
            objc["recipe"] = ""
            return render_to_response('addRecipe.html',
                objc,
                context_instance = RequestContext(request))
    else:
        request.session['red']= "/project3/add"
        return HttpResponseRedirect("/project3/login")



def showAddRecipeUrl(request):
    if "userid" in request.session:
        return render_to_response('addRecipeUrl.html',
            objc, 
            context_instance = RequestContext(request))
    else:
        request.session['red']= "/project3/add/import"
        return HttpResponseRedirect("/project3/login")


def showLogin(request):
    obj = {}
    obj["error_message"] = ""
    obj["registered"] = ""

    if request.method == "POST":
        if ('red' not in request.session) or (not request.session["red"]):
            print "in if "
            next= '/project3/recipes/'
        else:
            print "in else"
            next= request.session["red"]

        try:
            username = request.POST['username']
            password = request.POST['password']
            user = authenticate(username=username, password=password)
        except:
            user = authenticate(request=request)

        if user is not None:
            if user.is_active:
                login(request, user)
                request.session["userid"] = user.id

                # Redirect to a success page.
                return HttpResponseRedirect(next)

Answer 3

我猜你是在用Apache的CGI功能。这意味着每次请求时，脚本都会重新启动。这就导致每次调用时，全局变量都会被重新初始化。

另外，使用全局变量来存储本质上是会话数据（每个用户都有自己的会话和状态）其实并不是个好主意。全局变量对所有用户都是一样的，而会话是针对每个用户的，这正是你想要的。

在你的情况下，这些会话数据可能应该存储在某个数据库中，因为当你的脚本执行完毕并且页面渲染完成后，Python解释器就会结束。