Custom ModelForm class with django-crispy-forms' FormHelper. You can optionally provide your own layout

crispy_modelform_with_formhelper.py

from django.forms import ModelForm
from crispy_forms.helper import FormHelper
from crispy_forms.bootstrap import FormActions
from crispy_forms.layout import Layout, HTML, Div, Submit

# Put it variable to avoid writing it twice
buttons_layout = Layout(
    Div(
        HTML('<br>'),
        FormActions(
            Submit('submit', 'Save'),
            HTML('<a class="btn btn-secondary" href="{{ request.META.HTTP_REFERER }}">Cancel</a>')
        ),
        css_class='row justify-content-center',
    ),
)


class CrispyModelFormWithHelper(ModelForm):
    """
    Custom ModelForm with a FormHelper.
    Optionally a helper_custom_layout can be provided.
    """
    helper_custom_layout = None
    
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        custom_layout = self.helper_custom_layout
        self.helper = FormHelper(self)
        self.helper.form_class = 'form-horizontal'
        self.helper.label_class = 'col-md-12'
        self.helper.field_class = 'col-md-12'
        if custom_layout:
            self.helper.layout = Layout(custom_layout, buttons_layout)
        else:
            self.helper.layout.append(buttons_layout)