Почему база данных не заполняется даже после успешного рендеринга и отправки формы в моем приложении django?

Я начинающий django и делаю простую форму регистрации книги для заполнения базы данных sql3. Я думаю, что сделал все правильно, и форма отображается правильно, и при нажатии кнопки submit она даже отправляет POST запрос, но база данных не заполняется. Я исследовал эту проблему все выходные, просмотрел документацию по bootstrap, а также изучил функцию is_valid(). Она выдает ошибку типа "

from django.db import models
class Book(models.Model):
    #Create your models here
    book_name = models.CharField(max_length=200)
    page =models.CharField(max_length=20)
    authors =models.CharField(max_length=200)
    registration = models.CharField(max_length=200)
    #email = models.EmailField(max_length=100)
    def __str__(self):
        return self.book_name
```
views.py

```
from django.shortcuts import render
from django.http import HttpResponse
from . models import Book
from .forms import BookForm
def say_hello(request):
    if(request.method=="POST"):
        #if Post request is made :do something
        form = BookForm(request.POST or None)
        if form.is_valid():
            print("New Book Object is created")
            #Book.objects.create(**form.cleaned_data)
            form.save()
        else:

            print(form.errors)
            print("Invalid Form data")

        return render(request,'join.html',{})
        #Add all things posted to the Bookform

    else:
        #otherwise just reder a normal web page
        return render(request,'join.html',{})
def index(request):
    all_books=Book.objects.all
    return render(request,'index.html',{'all':all_books})
# Create your views here.
```


forms.py
```
from django import forms
from . models import Book
#To post data to the datbase obtained from form
class BookForm(forms.ModelForm):
    class Meta:
        model = Book
        fields = ['book_name','authors','page','registration']

```
    

join.html
```
{%  extends 'base.html' %}<!-- We are including bootstrap loaded base.html file-->
{% block content %}

    <h1>    Register Your Favorite Book
        </h1>
    <p>
    <form method="POST" action="{% url 'hello' %}"> <!-- It says that Call view function respective to 'hello url -->
    {% csrf_token  %} <!-- IT's for security from hacker-->
        <p>
  <div class="form-group">
    <label for="">Book Name</label>
    <input type="text" class="form-control" id="book_name" placeholder="Enter Book Name",name="book_name">
  </div>
  <div class="form-group">
    <label for="authors_name">Authors</label>
    <input type="text" class="form-control" id="author_name" placeholder="Authors' Name" name="authors">
  </div>
         <div class="form-group">
    <label for="Pages">No. Of Pages</label>
    <input type="text" class="form-control" id="page_no" placeholder="No. of Pages" name="page">
              <div class="form-group">
    <label for="Registration">Registration No</label>
    <input type="text" class="form-control" id="reg_no" placeholder="Book Registration No" name="registration">
  </div>
  </div>
  <button type="submit" class="btn btn-primary">Submit</button>
</form>
    </p>
    </body>
{% endblock %}```


 

else:
    # otherwise just reder a normal web page
    return render(request, 'join.html', {'form': BookForm()})

{{ form }}

def say_hello(request):
    if request.method == "POST":   # don't use parenthesis for if statement, it's redundant in Python :)
        form = BookForm(request.POST or None)
        if form.is_valid():
            ...
        else:
            ...
    elif request.method == "GET":
        form = BookForm()
        ...
    return render(request, 'join.html', {'form': form})