How to select an instance of a model from a queryset django? - python-3.x

Question

I am creating a project for hosting cricket tournaments. I have created 3 apps in it: home, tournament and team. After adding a tournament, when entering the tournament's detail view, I can add a team to the tournament. My Team model has a ForeignKey to my Tournament model, and my Tournament model has a ForeignKey to my User model(built-in django user model). When creating a team, I want to save the team for a particular tournament. I don't understand how to access the exact tournament and save the team for that tournament only.
My tournament detail html:
{% extends 'menu.html' %}
{% block content %}
<div class="row">
<div class="col-8">
<table class="table table-bordered table-hover">
<tr>
<th scope="col">Match between</th>
<th scope="col">Winner</th>
</tr>
{% for match in match_list %}
<tr>
<td>
{{ match.team1.name }} vs {{ match.team2.name }}
</td>
<td>
{% if match.winner %}
{{ match.winner.name }}
{% else %}
TBD
{% endif %}
</td>
</tr>
{% endfor %}
</table>
</div>
<div class="col-4">
{% if teamscount < tournament.no_of_teams %}
<button class="btn btn-primary" onclick="window.location.href='{% url 'teams:addteam' %}'">Add Team</button>
{% endif %}
</div>
</div>
{% endblock content %}
My urls.py file in tournament app:
from django.urls import path, include
from . import views
app_name='tournaments'
urlpatterns = [
path('all/', views.TournamentListView.as_view(), name='all'),
path('create/', views.TournamentCreateView.as_view(), name='create'),
path('view/<int:pk>/', views.TournamentDetailView.as_view(), name='detail'),
]
My urls.py file in teams app:
from django.urls import path
from . import views
app_name="teams"
urlpatterns = [
path('new/', views.TeamCreateView.as_view(), name="addteam"),
]
My views.py file in teams app:
from django.shortcuts import render
from django.views.generic import CreateView
from .models import Team
from django.urls import reverse_lazy
from tournament.models import Tournament
class TeamCreateView(CreateView):
model = Team
fields = ['name', 'no_of_players',]
success_url = reverse_lazy('tournaments:all')
success_message = "Tournament Created!!"
def get_form(self):
form = super().get_form()
return form
def form_valid(self, form):
print('form_valid called')
object = form.save(commit=False)
object.tournament = Tournament.objects.filter(user = self.request.user)
object.save()
return super(TeamCreateView, self).form_valid(form)
My create team html file:
{% extends 'menu.html' %}
{% load crispy_forms_tags %}
{% block content %}
{% load bootstrap4 %}
{% bootstrap_css %}
{% bootstrap_javascript jquery='full' %}
{{ form.media }}
<form
action="{% url 'teams:addteam' %}"
method="post"
id="upload_form"
enctype="multipart/form-data"
>
{% csrf_token %} {{ form|crispy }}
<div class="form-group">
<button class="btn btn-outline-info" type="submit">Create</button>
<input class="btn btn-danger" type="submit" onclick="window.location='{% url 'tournaments:all' %}' ; return false;" value="Cancel" />
</div>
</form>
{% endblock content %}
How can I save this team to the specific tournament model, or do I need to change the way I've designed the functions and classes?

Answer 1

For what i understood your models have the following design:
class Tournament(models.Model):
name = models.CharField(max_length=50)
user = models.ForeignKey(
get_user_model(),
on_delete=models.CASCADE
)
def __str__(self):
return self.name
class Team(models.Model):
name = models.CharField(max_length=50)
tournament = models.ForeignKey(Tournament, on_delete=models.CASCADE)
def __str__(self):
return self.name
So, if you want to save a Team instance to a specific Tournament, you need to do the following:
# Grab the tournament instance in a variable (I recommend to use the id instead of the user. This is probably better, unless the user is unique per tournament, if not .get() will throw an error )
tournament = Tournament.objects.get(user=user)
# Then create your Team object like this
Team.objects.create(name='super team', tournament=tournament)
One of the problems i see is that you are using 'filter' alone to try to get an instance. 'Filter' returns a QuerySet. You have many choices to return a specific instance after using 'filter', you can do .filter().first() or .filter()[0] (or any number) and there are more