Django: Complex Formset with multiple foreignKeys - django

Question

I'm working on a project where users can vote on collections of books. My models look like this:
class Collection(models.Model):
id = models.AutoField(primary_key=True)
name = models.CharField(max_length=31)
class Book(models.Model):
id = models.AutoField(primary_key=True)
name = models.CharField(max_length=255)
collection = models.ForeignKey(Collection)
vote_choices = ((-1,'Bad'),
(0, 'Not good, Not bad'),
(1,'Good'))
class Vote(models.Model):
id = models.AutoField(primary_key=True)
user = models.ForeignKey(User, related_name='votes')
book = models.ForeignKey(Book)
vote = models.IntegerField(choices=vote_choices)
I need to display a view for the users where they can see all the books in a given collection and vote for those books at once, since this is much more user-friendly than looping over everybook to vote. So I need a formset where every form will be: a book and its vote.
Initially I thought this was a good opportunity to use formsets (I have never used them before, but I'm used to work with forms, modelforms), but I'm running into difficulties on how to create this formset.
I would like to use generic class based views, since, in theory, I could easily create/update all votes easily, but I can't figure out how to do this.
Right now, I don't have a direct relation between the Collection model and the User (from django.contrib.auth.model) model, but I don't mind adding one if this makes things easier. I don't really need one, since every User is linked to a Book through a Vote and every Book is linked to a Collection.
I'm not sure whether I should use formsets or just regular modelforms.
How would you do it? Thanks in advance for any help.

Answer 1

I would recommend not to use django forms for this case. There are some more convenient ways.
First way. Using pure jQuery
Extend your book class:
class Book(models.Model):
id = models.AutoField(primary_key=True)
name = models.CharField(max_length=255)
collection = models.ForeignKey(Collection, related_name='books')
def get_vote(self, user):
vote = Vote.objects.filter(book=self, user=user)
if vote:
return vote.vote
else:
return ''
Your views (you can rewrite it on CBV if you want):
def list_collection(request, collection_id):
collection = Collection.objects.get(pk=id)
user = request.user
books = []
for item in collection.books.all():
book = {
'id': item.pk,
'name': item.name,
'vote': item.get_vote(user)
}
books.append(book)
return render_to_response('colleciton.html', {'books': books})
def set_vote(request):
id = request.GET('id')
vote = int(request.GET('vote'))
user = request.user
book = Book.objects.get(pk=id)
vote = Vote()
vote.user = user
vote.vote = vote
vote.book = book
vote.save()
return HttpResponse()
Your urls:
url(r'^list-collection/', 'list_collection', name='list_collection'),
url(r'^set-vote/', 'set_vote', name='set_vote'),
Your django template:
{% extends 'base.html' %}
{% block content %}
{% for book in collection.books.all %}
<div class="book" data-id="{{ book.id }}">
<div class="book-name">{{ book.name]}</div>
<div class="book-vote" {% if not book.get_vote %}style="display:none"{% endif %}>book.get_vote</div>
<div class="voting" {% if book.get_vote %}style="display:none"{% endif %}>
<button class="vote-up"></button>
<button class="vote-down"></button>
</div>
</div>
{% endfor %}
{% endblock %}
And the javascript is like
$(document).ready(function(){
$('.vote-up, .vote-down').on('click', function(e){
var id, vote, t, book_el;
e.preventDefault();
t = $(e.currentTarget);
book_el = t.parents().parents()
id = book_el.attr('data-id');
if t.hasClass('vote-up'){
vote = 1;
} else {
vote = -1;
}
book_el.find('.book-vote').show();
book_el.find('.book-vote').text(vote);
book_el.find('voting').hide();
$.get("/set-vote", {vote: vote, id: id});
});
});
Second way. Using javascript frameworks like Backbone.js
It makes the whole process much easier. Especially if you plan to add some other features to your app.
From the other hand Backbone requires some time to learn it.
Read the docs, look at the tutorial app TodoMVC or other tutorials.
Maybe you'll find it more appropriate for your task.