[Fixed]-Django crispy forms: Nesting a formset within a form

A slight modification to the earlier answer by qris.

This update (as suggested by Alejandro) will allow for our custom Formset Layout Object to use a FormHelper object to control how the formset’s fields are rendered.

from crispy_forms.layout import LayoutObject

from django.template.loader import render_to_string


class Formset(LayoutObject):
    """ 
    Renders an entire formset, as though it were a Field.
    Accepts the names (as a string) of formset and helper as they
    are defined in the context

    Examples:
        Formset('contact_formset')
        Formset('contact_formset', 'contact_formset_helper')
    """

    template = "forms/formset.html"

    def __init__(self, formset_context_name, helper_context_name=None,
                 template=None, label=None):

        self.formset_context_name = formset_context_name
        self.helper_context_name = helper_context_name

        # crispy_forms/layout.py:302 requires us to have a fields property
        self.fields = []

        # Overrides class variable with an instance level variable
        if template:
            self.template = template

    def render(self, form, form_style, context, **kwargs):
        formset = context.get(self.formset_context_name)
        helper = context.get(self.helper_context_name)
        # closes form prematurely if this isn't explicitly stated
        if helper:
            helper.form_tag = False

        context.update({'formset': formset, 'helper': helper})
        return render_to_string(self.template, context.flatten())

Template (used to render formset):

{% load crispy_forms_tags %}

<div class="formset">
  {% if helper %}
    {% crispy formset helper %}
  {% else %}
    {{ formset|crispy }}
  {% endif %}
</div>

Now it can be used in any layout just like any other crispy forms layout object.

self.helper.layout = Layout(
    Div(
        Field('my_field'),
        Formset('my_formset'),
        Button('Add New', 'add-extra-formset-fields'),
    ),
)

# or with a helper
self.helper.layout = Layout(
    Div(
        Field('my_field'),
        Formset('my_formset', 'my_formset_helper'),
        Button('Add New', 'add-extra-formset-fields'),
    ),
)

This is currently not supported in crispy-forms. Your only option would be to use |as_crispy_field filter (not documented yet, sorry).

I have started development of this feature for {% crispy %} tag and in a feature branch, it’s all explained here: https://github.com/maraujop/django-crispy-forms/issues/144

I’m looking for feedback, so if you are still interested, feel free to post.

Basing on above solution Formset(LayoutObject), you would combine django-dynamic-formset & crispy.
On my order page I have:

• order’s section part 1
• order’s inline formset with dynamic-add forms
• order’s section part N

Now it is simple and clear, ModelForms are:

class OrderTestForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
    super(OrderTestForm, self).__init__(*args, **kwargs)
    self.helper = FormHelper(self)
    self.helper.form_tag = True
    self.helper.html5_required = True
    self.helper.form_action = 'test_main'
    self.helper.layout = Layout(
        'product_norms', #section 1
        'reference_other', #section 1
        # rest of the section 1 fields
        Formset('samples', 'helper'), # inline dynamic forms
        'checkbox_is_required' # start of section N
        # other order sections fields
    )
    self.helper.add_input(Submit("submit", "Save order"))

Formset helper layout:

class SamplesFormSetHelper(FormHelper):
def __init__(self, *args, **kwargs):
    super(SamplesFormSetHelper, self).__init__(*args, **kwargs)
    self.form_method = 'post'
    self.html5_required = True
    self.layout = Layout(
        Fieldset('',
        'description',
        'product', # foreign key
        'DELETE', # delete django-dynamic-formset
        css_class="formset_row"), # add-rows 
    )
    self.form_tag = False
    self.render_required_fields = False

Add/delete inlines, saving order with formset operations work as expected.