Select a valid choice. <some choice> is not one of the available choices - django-forms

Question

I am trying to build a Form which will show a choice field with options. Now these options changes for different kind of user. I am able to set the values in the choice field from view. The problem is when I click on "Submit" all the fields become empty and get the error like "Select a valid choice. 2 is not one of the available choices."
Logic to find the correct list of companies to show in the choice field.
def get_my_companies(user):
if user.profile.company.is_customer:
return (user.profile_set.company.id,user.profile_set.company.name)
elif user.is_superuser:
companies = Company.objects.filter(is_customer=True)
list_of_companies = [(c.id, c.name) for c in companies]
return list_of_companies
else:
list_of_groups = list(user.groups.values_list('name',flat = True))
list_of_companies = []
# ... some more logic to find appropriate list of companies for each such user
return list_of_companies
The logic is working correctly and the values are getting populated on the page load. Only problem occurs when I submit the form.
views.py
def home(request):
my_companies = get_my_companies(request.user)
myForm = device_readings_form()
myForm.fields['company'].choices = my_companies
if request.method == 'POST':
myForm = device_readings_form(request.POST)
is_historical = True
if myForm.is_valid():
cd = myForm.cleaned_data
company = cd.get('company')
#device = cd.get('device')
date_from = cd.get('date_from')
date_to = cd.get('date_to')
print(date_from)
print(date_to)
# .... some more stuff to work. Then I return the render using template
context = {
'readings': data,
'columns' : df.columns,
'range' : {
'from' : datetime.datetime.now().strftime('%Y-%m-%d')+ ' 00:00:00',
'to': datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S')
},
'is_historical' : is_historical,
'show_chart' : show_chart,
'form' : myForm
}
return render(request,'portal/home.html',context)
forms.py
class device_readings_form(forms.Form):
initial_from_date = datetime.date.today()
initial_to_date = initial_from_date + datetime.timedelta(days=1)
date_from = forms.DateField(initial=initial_from_date)
date_to = forms.DateField(initial=initial_to_date)
company = forms.ChoiceField()
portal/home.html
{% block sidebar %}
<div class="col-md-4">
<div class="content-section">
<p class='text-muted'> <h5>Get Historical Readings</h5>
<form method="POST" action="{% url 'portal-home' %}">
{% csrf_token %}
{{form|crispy}}
<button type="submit">Submit</button>
</form>
</p>
</div>
</div>
{% endblock sidebar %}
The problem is faced only in case of ChoiceField. If I remove the ChoiceField and keep only remaining two DateFields then form gets properly submitted and I am able to read the form values in the view.
Can you guys please point me in right direction what I am doing wrong?
I would like to get the form submitted properly and get the form values in the view to process.

Answer 1

SOLVED!!!
The solution is:
One need to set the choices in the form instance.
Modified the code like below:
forms.py
class device_readings_form(forms.Form):
company = forms.ChoiceField()
devices = forms.ChoiceField()
initial_from_date = datetime.date.today()
initial_to_date = initial_from_date + datetime.timedelta(days=1)
date_from = forms.DateField(initial=initial_from_date)
date_to = forms.DateField(initial=initial_to_date)
def __init__(self, companies, devices, *args, **kwargs):
super().__init__(*args, **kwargs)
self.fields['company'].choices = companies
self.fields['devices'].choices = devices
views.py
def home(request):
my_companies = get_my_companies(request.user)
my_devices, total_list = get_available_devices(my_companies)
is_historical = False
show_chart = False
myForm = device_readings_form(my_companies, total_list)
#myForm.fields['company'].choices = my_companies
if request.method == 'POST':
myForm = device_readings_form(my_companies, total_list, request.POST or None)
is_historical = True
if myForm.is_valid():
cd = myForm.cleaned_data
company = cd.get('company')
device = cd.get('devices')
date_from = cd.get('date_from')
date_to = cd.get('date_to')
print(company)
print(device)
print(date_from)
print(date_to)