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

Question

信息：

我想通过以下提供的示例来创建嵌套表单：

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

此页面上的教程似乎非常好&&它正在尝试解决我遇到的确切问题。

当没有 POST 请求数据（即我们从数据库执行初始填充）时，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，但我担心它会影响这里提供的信息）。

这是失败的 views.py 代码（以粗体显示）：

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 

我收到的错误消息是：

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

我已经挖得更深了，看来这个失败发生在 site-packages/django/forms/formsets.py 行

该is_valid()检查失败，因为一些managementform所需的数据（形状TOTAL_FORMS的，形状和INITIAL_FORMS形状MAX_NUM_FORMS）是无效的。下面是 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 }}

{% 用于在buildings.forms 中构建%}

 {{ building }}

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

{% 结束为 %}

视图.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)

表格.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)

笔记：

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

• 我正在使用 Django V1.5

问题：

如果没有 POST 数据并且表单仅从数据库生成，那么应该如何正确填写 'form-TOTAL_FORMS' && 'form-INITIAL_FORMS' 数据以解决此故障？

Answer 1

更新：

在查看您提供的示例forms.py后，add_fields()方法末尾有一个片段，内容如下：

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

该data参数导致问题，因为它最初是空的，并且在内部 Django 将确定表单是否受与此类似的条件约束：

self.is_bound = data is not None

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

正如您所看到的，Python 中的空字典不是 None，因此即使不是，您TenantFormset也被视为bound表单。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)
]

您可以发布视图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>