inline_formset in django

coach_create.html

{% extends "staff_base.html" %}

{% load bootstrap3 %}

{% block title %}Salamander{% endblock %}
{% block content_title %}
<h1 class="page-header">Create coach</h1>
{% endblock %}

{% block content %}
<div class="row sub-header">
  <h2 class="col-md-4">
    Create a coach
  </h2>
</div>
<div class = "row">
  </br>
  <div class="col-md-5">
    <form action="" method="POST">
      {% csrf_token %}

      {%bootstrap_form form%}
  </div>
  <div class="col-md-5 col-md-offset-1">
    {{ coach_item_form.management_form }}
    {{ coach_item_form.non_form_errors }}
    {% for form in coach_item_form %}
    {%bootstrap_form form%}
    {% endfor %}

  </div>
</div>
<div class = "row">
  <div class = "col-md-12" style = "text-align:cneter" >
    <input type="submit" class="btn btn-primary center-block" value="Envoyer"/>
    </form>
  </div>
</div>
{% endblock %}

forms.py

from django.forms.models import inlineformset_factory
from staffManagement.models import MyUser, Coach

class MyUserForm(forms.ModelForm):
    class Meta:
        model = MyUser
        fields = ['first_name', 'last_name', 'email', 'street_number', 'street', 'zip_code', 'city', 'phone_number', 'birthday']
        
CoachFormSet = inlineformset_factory(MyUser, Coach, can_delete=False,
        fields = ('weight', 'height', 'first_position', 'second_position',
            'number', 'emergency_first_name', 'emergency_last_name',
            'emergency_function', 'emergency_phone'))

view.py

from staffManagement.models import Coach, Player
from staffManagement.models import MyUser as Member
from staffManagement.forms import *
from django.views.generic import CreateView

class CoachCreateView(WithUserMixin, CreateView):
    """Create a coach
    """

    model = MyUser
    form_class = MyUserForm
    template_name = "staffManagement/coach_create.html"
    success_url = "/staff/"

    def get(self, request, *args, **kwargs):

        self.object = None
        form_class = self.get_form_class()
        form = self.get_form(form_class)
        coach_item_form = CoachFormSet()
        return self.render_to_response(self.get_context_data(form = form, coach_item_form = coach_item_form))

    def post(self, request, *args, **kwargs):

        self.object = None
        form_class = self.get_form_class()
        form = self.get_form(form_class)
        coach_item_form = CoachFormSet(self.request.POST)

        if form.is_valid() and coach_item_form.is_valid():
            return self.form_valid(form, coach_item_form)
        else:
            return self.form_invalid(form, coach_item_form)

    def form_valid(self, form, coach_item_form):
        self.object = form.save(commit = False)
        self.object.team = self.request.user.team
        salt = os.urandom(2).encode('hex')
        username = str(self.object.last_name + self.object.first_name +
                self.object.team.name + salt)
        self.object.username = username
        self.object.save()

        coach_item_form.instance = self.object
        coach_item_form.save()

        return HttpResponseRedirect(self.get_success_url())

    def form_invalid(self, form, coach_item_form):
        return self.render_to_response(self.get_context_data(form = form, coach_item_form = coach_item_form))