Followers and Following:

This part we need to actually import “Follow” function.
I did some tests yesterday, and that note includes some related techniques:
https://www.yuque.com/akiencore/qgdgg5/ksg9eu

import new features and models:

• in /profiles/models.py
  • add FollowerRelation
  • add 3 variables in Profile ```python class FollowerRelation(models.Model): user = models.ForeignKey(User, on_delete=models.CASCADE) profile = models.ForeignKey(“Profile”, on_delete=models.CASCADE) timestamp = models.DateTimeField(auto_now_add=True)

class Profile(models.Model):

# A OneToOneField is essentially the same as a ForeignKey
user = models.OneToOneField(User, on_delete=models.CASCADE)
location = models.CharField(
    max_length=220, null=True, blank=True)  # allow null and blank
bio = models.TextField(blank=True, null=True)
# new
timestamp = models.DateTimeField(auto_now_add=True)
updated = models.DateTimeField(auto_now=True)
followers = models.ManyToManyField(User, related_name="following", blank=True)
"""
project_obj = Profile.objects.first()
project_obj.followers.all() -> All users following this profile
users.following.all() -> All users I follow
"""

- becuase we have changed the model, makemigration and migrate as usual
```bash
[root@localhost Twittme]# python3 ./manage.py makemigrations
You are trying to add the field 'timestamp' with 'auto_now_add=True' to profile without a default; the database needs something to populate existing rows.
 1) Provide a one-off default now (will be set on all existing rows)
 2) Quit, and let me add a default in models.py
Select an option: 1
Please enter the default value now, as valid Python
You can accept the default 'timezone.now' by pressing 'Enter' or you can provide another value.
The datetime and django.utils.timezone modules are available, so you can do e.g. timezone.now
Type 'exit' to exit this prompt
[default: timezone.now] >>> timezone.now
Migrations for 'profiles':
  profiles/migrations/0002_auto_20200729_2241.py
    - Add field followers to profile
    - Add field timestamp to profile
    - Add field updated to profile
    - Create model FollowerRelation
[root@localhost Twittme]# python3 ./manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, profiles, sessions, tweets
Running migrations:
  Applying profiles.0002_auto_20200729_2241... OK

test case:

• we simulate a following step in test file
• in /profiles/tests.py
  • setup 2 users, run 2 tests cases
    • make sure 2 corresponding profiles are created
    • add a follower to a user, and check their following status ```python from django.test import TestCase

Create your tests here.

from django.contrib.auth import get_user_model from .models import Profile

User = get_user_model()

class ProfileTestCase(TestCase): def setUp(self): self.user = User.objects.create_user( username=’cfe’, password=’somepassword’) self.userb = User.objects.create_user( username=’cfe-2’, password=’somepassword2’)

def test_profile_created_via_signal(self):
    qs = Profile.objects.all()
    self.assertEqual(qs.count(), 2) # the count of profiles is 2
def test_following(self):
    first = self.user
    second = self.userb
    first.profile.followers.add(second)  # first is followed by second
    second_user_following_whom = second.following.all() # check who second is following
    qs = second_user_following_whom.filter(user=first) # check is second following first
    first_user_following_no_one = first.following.all()
    self.assertTrue(qs.exists()) # second should now following first
    self.assertFalse(first_user_following_no_one.exists()) # first should now not following anyone

run test case for only "profiles" app: 
```bash
[root@localhost Twittme]# python3 ./manage.py test profiles
Creating test database for alias 'default'...
System check identified no issues (0 silenced).
..
----------------------------------------------------------------------
Ran 2 tests in 1.159s
OK
Destroying test database for alias 'default'...

all 2 cases passed.