我无法验证Django表单中的文件域

from django import forms

class MyForm(forms.Form):
    file_field = forms.FileField()

def my_view(request):
    if request.method == 'POST':
        form = MyForm(request.POST, request.FILES)
        # ...

def my_view(request):
    if request.method == 'POST':
        form = MyForm(request.POST, request.FILES)
        if form.is_valid():
            # 处理有效的表单数据
            file = form.cleaned_data['file_field']
            # ...

def my_view(request):
    if request.method == 'POST':
        form = MyForm(request.POST, request.FILES)
        if form.is_valid():
            # 处理有效的表单数据
            file = form.cleaned_data['file_field']
            # ...
        else:
            # 处理无效的表单数据
            errors = form.errors
            # ...