Django Form not saving

Question

I am relatively new to django and i'm trying to implement some modelforms.

My page consists of two views, a Politics section and a Sports section, each one with the same form for making comments (my comment model is named Comentario). It has a field for the content and a field for the section the comment belongs to. Both views are basically the same so I'm going to showcase just the politics one:

from django.contrib import messages
from django.shortcuts import render
from django.views.generic import CreateView

from usuarios.models import Usuario

from .forms import CrearComentario
from .models import Comentario

usuarios = Usuario.objects.all()
comentarios = Comentario.objects.all()
pag = ''

def politics(request):
    if request.user.is_authenticated:
        if request.method == 'POST':
            form = CrearComentario(request.POST, instance=request.user)
            if form.is_valid():
                messages.success(request, 'Publicado!')
                pag = 'politics'
                form.save()
                form = CrearComentario()
        else:
            form = CrearComentario(request.POST,instance=request.user)
    else:
        messages.warning(request, 'Comentario no válido')
        form = CrearComentario(request.POST)
    return render(request, 'main/politics.html', {'usuarios': usuarios,
                                                'comentarios': comentarios,
                                                'form': form})

In case you're wondering, 'pag' is a control variable that is checked by my signals.py file to update the 'pagina' field

I had trouble with the submit buttons in my custom modelsforms, the form displays correctly, and when I write something in the form and submit it, it displays a success message but the comment doesn't appear in the comment section and it doesn't appear in the django shell either.

politics.html

{% extends 'main/base.html' %}
{% load static %}
{% load crispy_forms_tags %}
<!-- Here would be the content-->
{% block comentarios %}
    <h3>Comentarios</h3>
    <ul class="a">
  {% for comment in comentarios %}
    {% if comment.pagina == 'politics' %}
        <li>
            <span>{{ comment.contenido }}</span>
            <br>
            <small>{{ comment.usuario }} , {{ comment.fecha }}</small>
            <hr>
            <br>
         </li>
    {% endif %}
  {% endfor %}
        </ul>
  {% if user.is_authenticated %}
        <form method="POST" enctype="multipart/form-data" action="http://localhost:8000/main/politics/">
          {% csrf_token %}
          <fieldset class="form-group">
              <legend>Dejanos tu opinion</legend>
                  {{ form|crispy }}
          </fieldset>
          <div class="form-group">
              <button class="btn btn-outline-info" type="submit">OK</button>
          </div>
      </form>
  {% else %}
   <legend>Inicia sesión para poner comentarios</legend>
  {% endif %} 

{% endblock %}

My forms.py looks like this:

from django import forms
from .models import Comentario

class CrearComentario(forms.ModelForm):
    contenido = forms.CharField(max_length = 250, required=False, widget=forms.Textarea)
    pagina = forms.CharField(max_length = 250, required=False, widget=forms.HiddenInput())

    class Meta:
        model = Comentario
        fields = ['contenido', 'pagina']

The field that determines to which section the comment belongs to ('pagina') is hidden because it's meant to be set by my signals.py file:

from django.db.models.signals import pre_save
from django.dispatch import receiver
from .models import Comentario
from .views import pag
from .forms import CrearComentario


@receiver(pre_save, sender=Comentario)
def fijar_pagina(sender, instance, **kwargs)
    if pag:
        instance.pagina = pag
        pag = ''
        instance.save(update_fields['pagina'])

I'm not getting any error message, and everything behaves like it should except for the fact that comments aren't being saved

I tried too a commit==False save instead of the signals but it was just as ineffective:

def politics(request):
    if request.user.is_authenticated:
        if request.method == 'POST':
            form = CrearComentario(request.POST, instance=request.user)
            if form.is_valid():
                messages.success(request, 'Publicado!')
                pag = 'politics'
                comentario = form.save(commit=False)
                comentario.pagina = 'sonsol'
                comentario.save()
                form = CrearComentario()
        else:
            form = CrearComentario(request.POST,instance=request.user)
    else:
        messages.warning(request, 'Comentario no válido)
        form = CrearComentario(request.POST)
    return render(request, 'main/politics.html', {'usuarios': usuarios,
                                                'comentarios': comentarios,
                                                'form': form})

Answer 1

usuarios and comentarios have both been defined at the module (file) level. As such they will not update for the lifetime of the process.

You should move both of these into the view body so that the query is run on every request

usuarios = Usuario.objects.all()
comentarios = Comentario.objects.all()
return render(request, 'main/politics.html', {'usuarios': usuarios,
                                            'comentarios': comentarios,
                                            'form': form})