Django 管理表单失败，因为 'form-TOTAL_FORMS' 和 'form-INITIAL_FORMS' 未正确填充

Question

信息:

我想创建嵌套表单，最好通过以下位置提供的示例进行描述:

http://yergler.net/blog/2009/09/27/nested-formsets-with-django/

此页面上的教程似乎相当不错 && 它正在尝试解决我遇到的确切问题。

当没有 POST 请求数据时(即我们正在从数据库执行初始填充)，views.py 文件中的此实现似乎存在问题。

代码可以在上面提供的 URL 中看到(如果需要我可以发布一些代码，但我担心它会带走这里提供的信息)。

这是失败的 views.py 代码(粗体):

block = get_object_or_404(models.Block, id=block_id)

if request.method == 'POST':
    formset = forms.BuildingFormset(request.POST, instance=block)

    if formset.is_valid():
        rooms = formset.save_all()

        return redirect('block_view', block_id=block.id)

else:
    formset = forms.BuildingFormset(instance=block)  #This is the line that is throwing the ValidationError 

我得到的错误信息是:

ValidationError at "urlName":
[u'ManagementForm data is missing or has been tampered with']

我已经深入挖掘，看来这个失败发生在 site-packages/django/forms/formsets.py 行

is_valid() 检查失败，因为一些管理表单所需的数据(form-TOTAL_FORMS、form-INITIAL_FORMS 和 form-MAX_NUM_FORMS)无效。以下是 self.errors 的实际输出:

{u'TOTAL_FORMS': [u'This field is required.'], u'INITIAL_FORMS': [u'This field is required.']}

代码:

edit_building.html:

{{ buildings.management_form }}

{% for building in buildings.forms %}

 {{ building }}

 {% if building.nested %}   
   {% for formset in building.nested %}   
     {{ formset.as_table }}   
   {% endfor %}   
 {% endif %}

{% endfor %}

views.py:

def should_delete(self, form):
    """Convenience method for determining if the form’s object will
    be deleted; cribbed from BaseModelFormSet.save_existing_objects."""

    if self.can_delete:
        raw_delete_value = form._raw_value(DELETION_FIELD_NAME)
        should_delete = form.fields[DELETION_FIELD_NAME].clean(raw_delete_value)
        return should_delete

    return False

def save_all(self, commit=True):
    """Save all formsets and along with their nested formsets."""

    # Save without committing (so self.saved_forms is populated)
    # — We need self.saved_forms so we can go back and access
    #    the nested formsets
    objects = self.save(commit=False)

    # Save each instance if commit=True
    if commit:
        for o in objects:
            o.save()

    # save many to many fields if needed
    if not commit:
        self.save_m2m()

    # save the nested formsets
    for form in set(self.initial_forms + self.saved_forms):
        if self.should_delete(form): continue

        for nested in form.nested:
            nested.save(commit=commit)

表单.py:

def should_delete(self, form):
    """Convenience method for determining if the form’s object will
    be deleted; cribbed from BaseModelFormSet.save_existing_objects."""

    if self.can_delete:
        raw_delete_value = form._raw_value(DELETION_FIELD_NAME)
        should_delete = form.fields[DELETION_FIELD_NAME].clean(raw_delete_value)
        return should_delete

    return False

def save_all(self, commit=True):
    """Save all formsets and along with their nested formsets."""

    # Save without committing (so self.saved_forms is populated)
    # — We need self.saved_forms so we can go back and access
    #    the nested formsets
    objects = self.save(commit=False)

    # Save each instance if commit=True
    if commit:
        for o in objects:
            o.save()

    # save many to many fields if needed
    if not commit:
        self.save_m2m()

    # save the nested formsets
    for form in set(self.initial_forms + self.saved_forms):
        if self.should_delete(form): continue

        for nested in form.nested:
            nested.save(commit=commit)

注意事项:

• 我已经在 https://docs.djangoproject.com/en/dev/topics/forms/formsets/#understanding-the-managementform 查看了 django 文档并且没有找到任何有用的内容来讨论 DJANGO 如何自动填充这些值

• 我正在使用 Django V1.5

问题:

在没有POST数据的情况下，如果只从数据库生成表单，应该如何正确填写'form-TOTAL_FORMS' && 'form-INITIAL_FORMS'数据来解决这个问题？

Answer 1

更新:

看完the example您在 add_fields() 方法末尾的 forms.py 中提供了这样一段代码:

# store the formset in the .nested property
form.nested = [
    TenantFormset(data = self.data,
                  instance = instance,
                  prefix = 'TENANTS_%s' % pk_value)
]

data 参数引起了问题，因为它最初是空的，并且 Django 内部将确定表单是否为 is bound。通过类似于此的条件:

self.is_bound = data is not None

# Example
>>> my_data = {}
>>> my_data is not None
True

正如您所见，Python 中的空字典不是 None，因此您的 TenantFormset 被视为 bound 表单，即使它不是。您可以使用以下内容修复它:

# store the formset in the .nested property
form.nested = [
    TenantFormset(data = self.data if any(self.data) else None,
                  instance = instance,
                  prefix = 'TENANTS_%s' % pk_value)
]

---

您可以发布 View 和表单代码以及表单的模板代码吗？

我的猜测是您没有在模板中使用“management_form”(它添加了您缺少的“form-TOTAL_FORMS”和“form-INITIAL_FORMS”字段)，即

<form method="post">
    {{ formset.management_form }}
    <table>
        {% for form in formset %}
        {{ form }}
        {% endfor %}
    </table>
</form>