python django django-models foreign-keys django-model-field

A count of ForeignKey

I have class Team, which means a group of users. And the relation with User is One-to-Many.

class Team(models.Model):
        member = models.ForeignKey(User, null=True, on_delete=models.SET_NULL)

But Team may consist of 2 and N members. I think to write manually is not our way, because it depends on count of people which is always variable.

 class Team(models.Model):
    member1 = models.ForeignKey(User, null=True, on_delete=models.SET_NULL)   
    member2 = models.ForeignKey(User, null=True, on_delete=models.SET_NULL)
    member3 = models.ForeignKey(User, null=True, on_delete=models.SET_NULL)

How can I do it more elegant and rational? I mean to connect count variable and ForeignKeys associating with users.

upd 15:17 UTC. I still don't understand how to make this. Sorry. So, let's begin to draw.

For example, I wrote simple code

class Event(models.Model):
    id_user = models.ForeignKey(User, null=True, on_delete=models.SET_NULL)

But when I go to admin panel to add Event, I can add only one user. But I need to add a lot of users, who want to participate in the Event and then to divide them into Teams. I think I don't need another class Member. It seems unnecessary. Am I wrong?

Solution

As you stated Team model, have ManyToOne relation that means ForeignKey.

But Team may consist of 2 and N members.

You should create two models Team and Member. In Member model, you can store all information related to members such as their age, gender, city, etc.

In Team model, you can store information related to particular team which consists of more than one Member i.e. It has ManyToOne relation with Member.

Models.py:

from django.db import models
from django.contrib.auth.models import User


class Member(models.Model):
    user = models.ForeignKey(User, on_delete=models.SET_NULL, null=True)

    def __str__(self) -> str:
        return f"{self.user.username}"


class Team(models.Model):
    member = models.ForeignKey(Member, on_delete=models.SET_NULL, null=True)

Registering in admin site:

admin.py:


@admin.register(Member)
class MemberAdmin(admin.ModelAdmin):
    list_display = ['id', 'user'] #Also specify other fields.


@admin.register(Team)
class TeamAdmin(admin.ModelAdmin):
    list_display = ['id', 'member'] #Also specify other fields.

Edit:

According to the current picture, a Event can have more than one Team as well as more than one User. So, make two separate Foreign keys for both the models.

models.py

from django.db import models
from django.contrib.auth.models import User


class Team(models.Model):
    # The below field is for name of team
    name = models.CharField(max_length=200)
    # The below field is for member of team.
    user = models.ForeignKey(User, null=True, on_delete=models.SET_NULL)

    def __str__(self) -> str:
        return f"{self.name}"


class Event(models.Model):
    # The below field is for name of event.
    name = models.CharField(max_length=200)
    # The below field is for user of event.
    user = models.ForeignKey(User, null=True, on_delete=models.SET_NULL)
    # The below is for team of event.
    team = models.ForeignKey(Team, on_delete=models.SET_NULL, null=True)

    def __str__(self) -> str:
        return f"{self.name}"

admin.py

from django.contrib import admin
from .models import Team, Event


@admin.register(Event)
class EventAdmin(admin.ModelAdmin):
    list_display = ['id', 'name', 'user', 'team']


@admin.register(Team)
class TeamAdmin(admin.ModelAdmin):
    list_display = ['id', 'name', 'user']

views.py

from django.shortcuts import render
from .models import Team, Event


def home(request):
    events = Event.objects.all()

    return render(request, 'any_app_name/home.html', {'events': events})

home.html or template file:

<body>
    <h2>All team information.</h2>

    <div>
        {% for event in events %}
        <h3>{{forloop.counter}}</h3>
        <p>Name of event: {{event.name}}</p>
        <p>Name of user related to this event: {{event.user.username}}</p>
        <p>Name of team related to this event: {{event.team.name}}</p>
        <br><hr>
        {% endfor %}
    </div>
</body>