How to pass foreign key in a hierarchical url in django? - html

Question

I have a hierarchy within my Django App. I want to achieve the following:
First show several boards
Then, if the user clicks on one board, I want to display all topics within the board.
Now the problem is that I have declared a foreign key within the Topic model, but now the topic can be called from each of the boards, not only from within the one I assigned it to.
Here my models:
from django.db import models
from django.contrib.auth.models import User
from mptt.models import TreeForeignKey
# overview over all topics
class Board(models.Model):
name = models.CharField(max_length=30, unique=True)
description = models.CharField(max_length=100)
def __str__(self):
return self.name
# topics withing the boards
class Topic(models.Model):
board = TreeForeignKey(Board, on_delete=models.CASCADE, related_name='Topic')
subject = models.CharField(max_length=255, unique=True)
last_updated = models.DateTimeField(auto_now_add=True) # auto_now_add sets current date+time when created
starter = models.ForeignKey(User, on_delete=models.CASCADE, related_name='Topic')
def __str__(self):
return self.subject
Then the views:
from .models import Board, Topic
class BoardsView(generic.ListView):
template_name = 'dbconnect/board.html'
context_object_name = 'board_list'
def get_queryset(self):
""" Return all boards."""
return Board.objects.all()
class TopicView(generic.ListView):
model = Topic
template_name = 'dbconnect/topic.html'
context_object_name = 'topic_list'
def get_queryset(self):
"""Return all topics."""
return Topic.objects.all()
The board.html works fine, since there is no second level in the url:
<div style = "text-align: left; margin-left: 10%; margin-right: 10%">
<div style = "display: inline-block; text-align: left;">
{% if board_list %}
<ul>
{% for board in board_list %}
<li>{{ board.name }}</li>
{% endfor %}
</ul>
{% else %}
<p>No boards are available.</p>
{% endif %}
</div>
But then comes topic.html and now I'm lost, what to pass, so that the topic refers to the board:
<div style = "text-align: left; margin-left: 10%; margin-right: 10%">
<div style = "display: inline-block; text-align: left;">
{% if topic_list %}
<ul>
{% for topic in topic_list %}
<li>{{ topic.subject }}</li>
{% endfor %}
</ul>
{% else %}
<p>No topics are available.</p>
{% endif %}
</div>
Here you can see my urls:
app_name = 'dbconnect'
urlpatterns = [
path('', views.BoardsView.as_view(), name = 'board'),
path('<int:topic>/', views.TopicView.as_view(), name='topic'),
path('<int:topic>/<int:level>/', views.LevelView.as_view(), name='level')]
How could I achieve that to show the restricted topic list inside each board?

Answer 1

The URLs
If I understand your question correctly, you should probably adapt your URLs to fit the case you describe:
urlpatterns = [
...
path('<int:board_id>/', views.TopicView.as_view(), name='topic-list'),
...
]
The first URL can stay the same, but the second URL gets the board_id as URL parameter, not the topic_id, since you want to display a list of topics belonging to the selected board.
And maybe rename that URL from topic to topic-list or something similar to be clearer what it is about.
Now, filtering inside the view:
You can filter your topic queryset like this:
class TopicView(generic.ListView):
model = Topic
...
def get_queryset(self):
return super().get_queryset().filter(board=self.kwargs['board_id'])
You can use super().get_queryset() there as you already defined model = Topic on the class; see the docs.
See this post for a similar case.