Dynamic form field based on another model's entries and save them in a m2m way in Django

form.py

from myapp.models import Attribute, Item, ItemAttribute
from django.forms import ModelForm, HiddenInput, IntegerField, CharField


class ItemForm(ModelForm):

    class Meta():
        model = Item
        exclude = ['attributes']

    def __init__(self, *args, **kwargs):
        self.request = kwargs.pop('request')
        super(ItemForm, self).__init__(*args, **kwargs);
        # Getting all attributes
        attributes = Attribute.objects.all()
        # Dynamically adding form field for each attribute
        for attr in attributes:
            # hardcodingly using char field type.
            # In future it will be dynamicly handled by the type
            # specified in attribute_type
            self.fields[attr.attribute] = CharField(required=True)

models.py

from __future__ import unicode_literals
from django.db import models

class Attribute(models.Model):
    TYPE_CHOICES = (
        ('text', 'text'),
        ('number', 'number')
    )
    attribute = models.CharField(primary_key=True, max_length=50)
    attribute_type = models.CharField(max_length=20, choices=TYPE_CHOICES)

    def __str__(self):              # __unicode__ on Python 2
        return self.attribute

class Item(models.Model):
    id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=50)
    attributes = models.ManyToManyField(Attribute, through='ItemAttribute')

    def __str__(self):              # __unicode__ on Python 2
        return  self.id

class ItemAttribute(models.Model):
    id = models.AutoField(primary_key=True)
    item = models.ForeignKey(Item, on_delete=models.CASCADE)
    attribute = models.ForeignKey(Attribute, on_delete=models.CASCADE)
    value = models.CharField(max_length=250)

views.py

from django.core.urlresolvers import reverse_lazy
from myapp.forms import ItemForm
from myapp.models import Item, ItemAttribute, Attribute

class ItemCreate(FormView):
    form_class = ItemForm
    template_name = 'myapp/item_form.html'
    success_url = reverse_lazy('item_list')
    
    # add the request to the kwargs
    def get_form_kwargs(self):
        kwargs = super(ItemCreate, self).get_form_kwargs()
        kwargs['request'] = self.request
        return kwargs

    def form_valid(self, form):
        item = form.save(commit = True)
        attributes = Attribute.objects.all()
        for attr in attributes:
            value = self.request.POST.get(attr.attribute)
            item_attribute = ItemAttribute.objects.create(item=item, attribute=attr, value=value)
        return super(ItemCreate, self).form_valid(form)