NOT NULL constraint failed: history.user_id - django

Question

I am new to Django and I am trying to learn by practicing with some project but I am stuck with this problem, I want to return the information of the History model to the authenticated user according to its id_user. The problem appears when the user gives the submit of the form.
The message that he gives me is this:
NOT NULL constraint failed: history.user_id
models.py
from django.db import models
from django.contrib.auth.models import User
class History(models.Model):
DAY35 = '35 days'
DAY45 = '45 days'
HISTORY_DAYS = (
(DAY35, '35 days'),
(DAY45, '45 days'),
)
user = models.ForeignKey(User, on_delete=models.CASCADE)
amount = models.FloatField(default=10)
days = models.CharField(
max_length=7,
choices=HISTORY_DAYS,
default=DAY35,
)
def is_upperclass(self):
return self.days in (self.DAY35, self.DAY45)
views.py
from django.utils.decorators import method_decorator
from django.contrib.auth.decorators import login_required
from django.views.generic.edit import CreateView
from .forms import HistoryForm
from .models import History
#method_decorator(login_required, name='dispatch')
class HistoryCreate(CreateView):
model = History
fields = ['amount', 'days']
success_url = reverse_lazy('history')
form_class = HistoryForm
forms.py
from django import forms
from .models import MiningHistory
class HistoryForm(forms.ModelForm):
class Meta:
model = History
fields = ['amount', 'days']
widgets = {
'amount': forms.NumberInput(attrs={'class':'x', 'placeholder':'0.00'}),
'days': forms.Select(attrs={'class':'x'}),
}

Answer 1

A History instance must have a non null user field. However you are not specifying the user related the History object you're creating.
In case you dont want to add the user, update you're model's user field :
user = models.ForeignKey(User, on_delete=models.CASCADE,blank=True,null=True)
If you want to associate the user field with the logged in user, update your views :
#method_decorator(login_required, name='dispatch')
class HistoryCreate(CreateView):
model = History
fields = ['amount', 'days']
success_url = reverse_lazy('history')
form_class = HistoryForm
def form_valid(self, form_class ):
form_class.instance.user= self.request.user
return super().form_valid(form)
Don't forget to add user to your form fields.
PS : Don't add user to your views modifiable fields. Check this for more details.