python - 未绑定(bind)本地错误 : local variable 'form' referenced before assignment in Django

Question

所以我正在做一个 Django 项目，这是我的 views.py 文件:

def new_topic(request, pk):
    board = get_object_or_404(Board, pk=pk)
    user = User.objects.first()  # TODO: get the currently logged in user

    if request.method == 'POST':
        form = NewTopicForm(request.POST)
    if form.is_valid():
        topic = form.save()
        return redirect('board_topics', pk=board.pk)
    else:
        form = NewTopicForm()
    return render(request, 'new_topic.html', {'form': form})

当我运行我的服务器时，我收到一条错误消息:

UnboundLocalError:赋值前引用了局部变量“form”

这是我的new_topic.html 文件

{% extends 'base.html' %}

{% block title %}Start a New Topic{% endblock %}

{% block breadcrumb %}
    <li class="breadcrumb-item"><a href="{% url 'home' %}">Boards</a></li>
    <li class="breadcrumb-item"><a href="{% url 'board_topics' board.pk %}">{{ board.name }}</a></li>
    <li class="breadcrumb-item active">New topic</li>
{% endblock %}

{% block content %}
    <form method="post">
        {% csrf_token %}
        {{ form.as_p }}
        <button type="submit" class="btn btn-success">Post</button>
    </form>
{% endblock %}

Answer 1

if form.is_valid(): 行在 GET 请求上失败，因为当 时您只定义了 form request.method == 'POST'.

这可以通过更改一些缩进来解决:

if request.method == 'POST':
    form = NewTopicForm(request.POST)
    if form.is_valid():
        topic = form.save()
        return redirect('board_topics', pk=board.pk)
else:
    form = NewTopicForm()
return render(request, 'new_topic.html', {'form': form})