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How to render many to many field data in Django template

I am able to render list of all courses and list of topics corresponding to the courses in different templates.
I need help to view list of all courses and when each course is clicked,a new page should show the list of associated topics
models.py
class Topic(models.Model):
topic_name = models.CharField(max_length=200, null=True)
topic_file = models.FileField(upload_to = "topic_file", blank=True, null=True)
def __str__(self):
return self.topic_name
class Course(models.Model):
course_name = models.CharField(max_length=200, null=True)
course_image = models.ImageField(upload_to="images", blank=True, null=True)
related_topic = models.ManyToManyField(Topic)
def __str__(self):
return self.course_name
Views.py
def view_course(request):
course_list = Course.objects.all()
context = {'course_list':course_list}
return render(request, 'upskill/view_course.html',context)
def course_topic(request,pk):
course_topic_list = Course.objects.get(id=pk)
var = course_topic_list.related_topic.all
context = {'var':var}
return render(request, 'upskill/course_topic.html',context)

Here is how you could get the related topics inside of a template.
{% for course in course_list %}
... data
{% for topic in course.related_topic.all %}
...data
{% endfor %}
{% endfor %}
If you don't want to do a query every single iteration of the {{course}} loop, I recommend you this in your views:
course_list = Course.objects.all().prefetch_related('related_topic')
And for a single object:
def course_topic(request,pk):
course = Course.objects.prefetch_related('related_topic').get(id=pk)
context = {'course ':course }
return render(request, 'upskill/course_topic.html',context)
And then in the template:
{{course.data...}}
{% for topic in course.related_topic.all %}
...data
{% endfor %}
To only have topics:
def topic_view(request, pk)
topics = Topic.objects.filter(course__pk=pk) #The reverse name of Course model.
# You can set a related name the "related_topic" field.
# Then access the above filter with that related name.
.... data
context = {
"topics":topics
}
return render(request, 'template.html', context)

ModelFormset in Django CreateView

I'm still new to Django & I would like to know how can allow user to add more than 1 ReferrerMember on Registration form as I wanted to achieve similar to the image url below
https://imgur.com/a/2HJug5G
I applied modelformset but so far it's giving me an error where "membership_id" violates not-null constraint the moment I submitted the form.
I've searched almost everywhere to find how to implement this properly especially on class-based view instead of function based view but still no luck. If possible please help me point out on any mistakes I did or any useful resources I can refer to
models.py
class RegisterMember(models.Model):
name = models.CharField(max_length=128)
email = models.EmailField()
class ReferrerMember(models.Model):
contact_name = models.CharField(max_length=100)
company_name = models.CharField(max_length=100)
membership = models.ForeignKey(RegisterMember, on_delete=models.CASCADE)
forms.py
class RegisterMemberForm(ModelForm):
class Meta:
model = RegisterMember
fields = ['name', 'email', ]
class ReferrerForm(ModelForm):
class Meta:
model = ReferrerMember
fields = ['contact_name ', 'company_name ', ]
ReferrerMemberFormset = modelformset_factory(ReferrerMember, form=RegisterMemberForm, fields=['contact_name ', 'company_name ', ], max_num=2, validate_max=True, extra=2)
views.py
class RegisterMemberView(CreateView):
form_class = RegisterMemberForm
template_name = 'register.html'
def post(self, request, *args, **kwargs):
member_formset = ReferrerMemberFormset (request.POST, queryset=ReferrerMember.objects.none())
if member_formset .is_valid():
return self.form_valid(member_formset )
def get_context_data(self, **kwargs):
context = super().get_context_data(**kwargs)
context['member_formset'] = ReferrerMember(queryset=ReferrerMember.objects.none())
return context
register.html
<form method="post">
{% csrf_token %}
{{form.as_p}}
{{member_formset.as_p}}
<input type="submit">
</form>

Django: Sort given results of method on model

In Django, how can I sort the results of a method on my model?
class Flashcard(models.Model):
owner = models.ForeignKey(User, on_delete=models.CASCADE)
deck = models.ForeignKey(Deck, on_delete=models.CASCADE)
question = models.TextField()
answer = models.TextField()
difficulty = models.FloatField(default=2.5)
objects = FlashcardManager()
def __str__(self):
return self.question
class Profile(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE,related_name='profile')
bio = models.TextField(max_length=500,null=True, default='',blank=True)
def __str__(self):
return f'{self.user.username} Profile'
def avg_diff_user(self):
avg_diff = Flashcard.objects.filter(owner = self.user).aggregate(Avg('difficulty'))['difficulty__avg']
return avg_diff
So with avg_diff_user, I get each user's average difficulty rating. Which I can then use in my leaderboard template as follows:
<ol>
{% for user in leaderboard_list %}
<li>{{user.username}}: {{user.profile.avg_diff_user|floatformat:2}}</li>
{% endfor %}
</ol>
The results show, but it's not sorted - how can I sort by avg_diff_user? I've read many similar questions on SO, but to no avail. I've tried a different method on my model:
def avg_diff_sorted(self):
avg_diff_sorted = Flashcard.objects.all().annotate(get_avg_diff_user=Avg(Flashcard('difficulty'))['difficulty__avg'].order_by(get_avg_diff_user))
return avg_diff_sorted
Which I don't think is right and didn't return any results in my template. I also tried the following, as suggested in https://stackoverflow.com/a/930894/13290801, which didn't work for me:
def avg_diff_sorted(self):
avg_diff_sorted = sorted(Flashcard.objects.all(), key = lambda p: p.avg_diff)
return avg_diff_sorted
My views:
class LeaderboardView(ListView):
model = User
template_name = 'accounts/leaderboard.html'
context_object_name = 'leaderboard_list'
def get_queryset(self):
return self.model.objects.all()

something like:
leaderboard_list = User.objects.all().annotate(avg_score=Avg('flashcard__difficulty').order_by('-avg_score')
will sort you the users by their average score.
I don't use ListView that often by if you just used a standard view like:
def LeaderboardView(request):
leaderboard_list = ...
context = {'leaderboard_list':leaderboard_list}
return render(request, 'accounts/leaderboard.html', context)
In your html you could do the same:
{% for user in leaderboard_list %}
...
{% endfor %}

Pre-populating a child models django create form with a parent's ID

I have followed the guidelines from This answer in order to pass Parent pk to the child creation page. At the moment though it is not working and I am seeing the following log.
[14/Jul/2017 13:15:37] "POST /catalog/productstatus/2/create/ HTTP/1.1" 200 4001
I'm not sure what I'm doing wrong, here is the code I currently have.
Models
Models.py
class Product(models.Model):
serial_number = models.CharField(unique=True, max_length=15)
class ProductStatus(models.Model):
serial_number = models.ForeignKey('Product', on_delete=models.CASCADE, null=True)
status = models.CharField(max_length=20, blank=True, default='Stock', help_text='Products status')
date = models.DateTimeField(auto_now_add=True)
View
class ProductStatusCreate(CreateView):
model = ProductStatus
template_name = 'catalog/productstatus_create.html'
form_class = ProductStatusModelForm
def form_valid(self, form):
productstatus = form.save(commit=False)
product_id = form.data['product_id']
product = get_object_or_404(Product, id=product_id)
productstatus.product = product
return super(ProductStatusCreate, self).form_valid(form)
def get_context_data(self, **kwargs):
context = super(ProductStatusCreate, self).get_context_data(**kwargs)
context['s_id'] = self.kwargs['product_id']
return context
def get_success_url(self):
if 'product_id' in self.kwargs:
product = self.kwargs['product_id']
else:
product = self.object.product.pk
return reverse_lazy('product_detail', kwargs={'pk': product})
Forms
class ProductStatusModelForm(forms.ModelForm):
class Meta:
model = ProductStatus
fields = ['status',]
def __init__(self, *args, **kwargs):
self.fields["product"] = forms.CharField(widget=forms.HiddenInput())
super(ProductStatusModelForm, self).__init__( *args, **kwargs)
templates/myapp/product_detail.html
New
urls.py
urlpatterns += [
url(r'^productstatus/(?P<product_id>\d+)/create/$', views.ProductStatusCreate.as_view(), name='productstatus_create'),
]
productstatus_create.html
{% extends "base_generic.html" %}
{% block content %}
<h2>New Product Status</h2>
</br>
<form action="" method="post">
{% csrf_token %}
<table>
<input type=hidden id="id_product" name="product" value="{{ s_id }}">
{{ form }}
</table>
<input type="submit" value="Submit" />
</form>
</br>
{% endblock %}
When looking at the page's source the value does get populated but when I submit the form nothing happens.

Why do you have views.ProductInstanceCreate.as_view() in your urls.py but the view you show is called ProductStatusCreate? Are you sure you are using the right view?

You are creating a 'product' hidden field in your form, but not providing a value for it anywhere. Your template output then has two product fields, and the latter (blank) is taken, so returns an error saying it is required.
None of this outputting the product ID to the template in order to read it back in is necessary - you always have the ID available to you in the URL kwargs.
You can get rid of your get_context_data, and the extra field code in the Form and template. Your form_valid can be something like:
def form_valid(self, form):
product = get_object_or_404(Product, id=self.kwargs['product_id'])
form.instance.product = product
return super().form_valid(form)
And product_id will always be in self.kwargs, so your get_success_url can be shorter too:
def get_success_url(self):
product = self.kwargs['product_id']
return reverse('product_detail', kwargs={'pk': product})

Trouble with order.by('?') .first() to get random content in Django

Update #4:
The for loop in slider.html is currently not pulling content after the last update. Slider.html was randomized; however, I'm getting four of the same story and the urls are not going to their appropriate detailed view page anymore.
List.html has been fixed and is now random.
slider.html - This section is still wonky, (updated - 4:19 p.m.)
{% for random_article in random_articles %}
<div class="slider">
<div class="group visible">
<div class="sliderItem">
<img src="{{random_article.relatedImage}}" alt="" class="sliderPicture">
<p class="related">{{random_article.title}}</p>
</div><!-- /.sliderItem -->
</div><!-- /.group -->
</div><!-- /.slider -->
{% endfor %}
Here is the URL error when I click to detailed view:
NoReverseMatch at /last-us
Reverse for 'detailed' with arguments '()' and keyword arguments '{u'slug': ''}' not found. 1 pattern(s) tried: ['(?P<slug>\\S+)']
New culprits (for why slider.html isn't working)
urls.py
from django.conf.urls import patterns, url
from . import views
urlpatterns = patterns(
'',
url(r'^$', views.BlogIndex.as_view(), name="list"),
url(r'^(?P<slug>\S+)', views.BlogDetail.as_view(), name="detailed"),
)
views.py (updated - 4:19 p.m.)
Added context['random_slider'] = FullArticle.objects.order_by('?')[:4] but I don't think this is the right approach. So that I can get four different articles vs. four of the same article randomized.
from django.views import generic
from . import models
from .models import FullArticle
# Create your views here.
class BlogIndex(generic.ListView):
queryset = models.FullArticle.objects.published()
template_name = "list.html"
def get_context_data(self, **kwargs):
context = super(BlogIndex, self).get_context_data(**kwargs)
context['random_article'] = FullArticle.objects.order_by('?').first()
return context
class BlogDetail(generic.DetailView):
model = models.FullArticle
template_name = "detailed.html"
def get_context_data(self, **kwargs):
context = super(BlogDetail, self).get_context_data(**kwargs)
context['object_list'] = models.FullArticle.objects.published()
return context
def get_context_data(self, **kwargs):
context = super(BlogDetail, self).get_context_data(**kwargs)
context['random_articles'] = FullArticle.objects.exclude(
pk=self.get_object().pk
).order_by('?')[:4]
return context
Original Problem
I'm using FullArticle.objects.order_by('?').first() to get a random article from my database, but it's currently giving the same article when I refresh the page. There is probably something missing from my models, view or how I'm calling it (using slice) in list.html or slider.html that is causing the problem.
The two parts I'm looking to make random on page load:
list.html (changed so that it's {{random_article.}} ) - This section of the problem is fixed.
<div class="mainContent clearfix">
<div class="wrapper">
<h1>Top 10 Video Games</h1>
{% for article in object_list|slice:":1" %}
<p class="date">{{article.pubDate|date:"l, F j, Y" }}</p> | <p class="author">{{article.author}}</p>
<img src="{{article.heroImage}}" alt="" class="mediumImage">
<p class="caption">{{article.body|truncatewords:"80"}}</p>
{% endfor %}
models.py
from django.db import models
from django.core.urlresolvers import reverse
# Create your models here.
class FullArticleQuerySet(models.QuerySet):
def published(self):
return self.filter(publish=True)
class FullArticle(models.Model):
title = models.CharField(max_length=150)
author = models.CharField(max_length=150)
slug = models.SlugField(max_length=200, unique=True)
pubDate = models.DateTimeField(auto_now_add=True)
updated = models.DateTimeField(auto_now=True)
category = models.CharField(max_length=150)
heroImage = models.CharField(max_length=250, blank=True)
relatedImage = models.CharField(max_length=250, blank=True)
body = models.TextField()
publish = models.BooleanField(default=True)
gameRank = models.CharField(max_length=150, blank=True, null=True)
objects = FullArticleQuerySet.as_manager()
def __str__(self):
return self.title
def get_absolute_url(self):
return reverse("FullArticle_detailed", kwargs={"slug": self.slug})
class Meta:
verbose_name = "Blog entry"
verbose_name_plural = "Blog Entries"
ordering = ["-pubDate"]

The problem is that you are setting the value of a class attribute at "compile time" and not each time the view is called. Instead, you could do:
class BlogIndex(generic.ListView):
queryset = models.FullArticle.objects.published()
template_name = "list.html"
def random_article(self):
return = FullArticle.objects.order_by('?').first()
Or:
class BlogIndex(generic.ListView):
queryset = models.FullArticle.objects.published()
template_name = "list.html"
def get_context_data(self, **kwargs):
context = super(BlogIndex, self).get_context_data(**kwargs)
context['random_article'] = FullArticle.objects.order_by('?').first()
return context
[update]
In list html, I only need one random article. In slider.html, I need four random articles, would I just tack on FullArticle.objects.order_by('?')[:4] somewhere in that def get_context_data snippet?
Yes. Make it plural in the view (don't forget to exclude the main article from the side list):
class BlogDetail(generic.DetailView):
model = models.FullArticle
template_name = "detailed.html"
def get_context_data(self, **kwargs):
context = super(BlogDetail, self).get_context_data(**kwargs)
context['random_articles'] = FullArticle.objects.exclude(
pk=self.get_object().pk
).order_by('?')[:4]
return context
At the template, do:
{% for random_article in random_articles %}
<div class="sliderItem">
<img src="{{random_article.relatedImage}}" alt="" class="sliderPicture">
<p class="related">{{random_article.title}}</p>
</div><!-- /.sliderItem -->
{% endfor %}

The generic listview just passes an object_list as context based on the queryset. In your case it means you have to either change the value of queryset in your view or override the get_context_data method and add your random item to it.
https://docs.djangoproject.com/en/dev/ref/class-based-views/mixins-multiple-object/#django.views.generic.list.MultipleObjectMixin.get_context_data