Python 局部变量'；上下文规则'；分配前参考

有人能解释一下这个错误是什么意思吗？什么是作业？上下文应该在哪里？还是我犯了其他错误？我是Django的新手。非常感谢你

def add_page(request, category_name_slug):
    try:
        cat = Category.objects.get(slug=category_name_slug)
    except Category.DoesNotExist:
        cat = None

    if request.method == 'POST':
        form = PageForm(request.POST)
        if form.is_valid():
            if cat:
                page = form.save(commit=False)
                page.category = cat
                page.views = 0
                page.save()
                # probably better to use a redirect here.
                return category(request, category_name_slug)
           else:
               print form.errors
        else:
            form = PageForm()

        context_dict = {'form':form, 'category': cat}

    return render(request, 'rango/add_page.html', context_dict)

我得到了这个错误：

local variable 'context_dict' referenced before assignment

例外的是，在返回render（reqyest，'rango/add_page.html'，context_dict）的行中指向我

---

相同的回溯

请尝试此代码，仅回复POST请求

def add_page(request, category_name_slug):
    try:
        cat = Category.objects.get(slug=category_name_slug)
    except Category.DoesNotExist:
        cat = None

    if request.method == 'POST':
        form = PageForm(request.POST)
        if form.is_valid():
            if cat:
                page = form.save(commit=False)
                page.category = cat
                page.views = 0
                page.save()
                # probably better to use a redirect here.
                return category(request, category_name_slug)
           else:
               print form.errors
        else:
            form = PageForm()

        context_dict = {'form':form, 'category': cat}
        # indented - only reply to post requests
        return render(request, 'rango/add_page.html', context_dict)
    # if this is not a post request, raise an exception (handle your way later..)
    raise Exception('NOT A POST REQUEST')

---

记住，在Python中，缩进很重要。问题在于变量

context\u dict

在if语句之外没有引用，因为它是如何缩进的。因此，在if语句之外声明变量

context\u dict

：

    context_dict = {}
    if request.method == 'POST':
    <rest of code here>

context_dict={}
如果request.method==“POST”：

我再次对我的代码进行了分解，这种方法很有效。我的context_dict现在位于if-outer语句之外，而else:form=PageForm（）现在位于outer-if语句中，与以前在internal-if语句中不同。谢谢你们帮助我

def add_page(request, category_name_slug):
    try:
        cat = Category.objects.get(slug=category_name_slug)
    except Category.DoesNotExist:
        cat = None

    if request.method == 'POST':
        form = PageForm(request.POST)
        if form.is_valid():
            if cat:
                page = form.save(commit=False)
                page.category = cat
                page.views = 0
                page.save()
                # probably better to use a redirect here.
                return category(request, category_name_slug)
            else:
                print form.errors
    else:
        form = PageForm()

    context_dict = {'category': cat, 'form': form}

    return render(request, 'rango/add_page.html', context_dict)

---

如果请求方法不是

'POST'

您不定义

context\u dict

，但您尝试在最后一行中使用它。这样我得到了错误：不是POST请求，但我实际上在If语句之外声明了变量context\u dict，并且它可以工作：）错误是故意的。您需要决定如何处理该错误，并在错误不是错误的情况下删除该错误。