I'm trying get user input from a HTML form and use that value to populate a ChartJS graph in my Django app called DisplayData which has a template called Display.html. I have the following form in my project.

Display.html

<div class="row">
    <form method="POST">
        {% csrf_token %}
        <input type="text" name="textfield">
        <button type="submit">Submit</button>
    </form>
</div>

In my views file, I have the following code to get the data from this form:

views.py

class ChartData(APIView):
    authentication_classes = []
    permission_classes = []

    display_id = 0

    def post(self, request, format=None):
        display_id = self.request.POST.get("textfield")

        try:
           display_id = int(display_id) 
        except ValueError: 
           display_id = 2

    def get(self, request, format=None):

        display_id = self.request.GET.get("textfield") 

        all_entries = models.Entries.objects.all().filter(parent=display_id) #change to input from text box via display_id
        all_id = models.Entries.objects.all().values_list('id', flat=True)
        all_measurables = models.Measurables.objects.all().filter(user_id=request.user.id) #change to current user



        all_times = [m.timestamp for m in all_entries]

        all_data = []
        for m in all_entries:
            data = m.data
            json_data = json.loads(data)
            value = json_data['value']
            all_data.append(value)


        data = {
            "labels": all_times,
            "default": all_data,
        }   
        return Response(data)

My urls are set up as follows.

urls.py

from .views import get_data, ChartData

urlpatterns=[
    url(r'^$',views.DisplayView, name='DisplayView'),
    url(r'^api/data/$', views.get_data, name='api-data'),
    url(r'^display/api/chart/data/$', views.ChartData.as_view()),
    url(r'^logs/', views.LogDisplay, name='Display-Logs'),
]

When I go into the form in the page and type in a number and hit submit, in my console I get the following error:

TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

What am I doing wrong?