Django incremental change in simultaneous ModelForm submission - django

Question

My model has a field working_hour which is PositiveIntegerField, I am using ModelForm and django-crispy-forms.Assume tow different people has rendered form with working_hour value 20 and both of them want to increase working_hour by 10 and they updates the working_hour form field from 20 to 30.When they both submit the form, updated working_hour becomes 30 in database, but it should be 40.
models.py
class OverallHour(models.Model):
working_hour = models.PositiveIntegerField()
views.py
class OverallHourUpdateView(LoginRequiredMixin, UpdateView):
model = OverallHour
form_class = OverallHourForm
success_url = reverse_lazy('home')
forms.py
class OverallHourForm(ModelForm):
class Meta:
model = OverallHour
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.helper = FormHelper()
self.helper.add_input(Submit('submit', 'UPDATE'))
overall_hour_form.html
{% extends "base.html" %}
{% load crispy_forms_tags %}
{% block content %}
<div class="row justify-content-center">
<div class="col-md-8">
<div class="card bg-light">
<div class="card-body">
{% crispy form %}
</div>
</div>
</div>
</div>
{% endblock content %}
I just need change delta from initial form value in the server when they submit the form.Can you please advice me on this issue?

Answer 1

I got the solution!
class OverallHourForm(ModelForm):
class Meta:
model = OverallHour
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.helper = FormHelper()
self.helper.add_input(Submit('submit', 'UPDATE'))
def clean(self):
cleaned_data = super(ProjectForm, self).clean()
print(self.has_changed())
print(self.changed_data)
print(self.initial)
print(cleaned_data)