mgt c8 checkpoint at tests

backend/app/models.py

@@ -9,6 +9,13 @@ import pydenticon, hashlib, base64
 from app import db, login
 from flask_login import UserMixin
 
+followers = sa.Table(
+        'followers',
+        db.metadata,
+        sa.Column('follower_id', sa.Integer, sa.ForeignKey('user.id'), primary_key=True),
+        sa.Column('followed_id', sa.Integer, sa.ForeignKey('user.id'), primary_key=True)
+)
+
 class User(UserMixin, db.Model):
     id: so.Mapped[int] = so.mapped_column(primary_key=True)
     username: so.Mapped[str] = so.mapped_column(sa.String(64), index=True, unique=True)
@@ -17,6 +24,16 @@ class User(UserMixin, db.Model):
     posts: so.WriteOnlyMapped['Post'] = so.relationship(back_populates='author')
     about_me: so.Mapped[Optional[str]] = so.mapped_column(sa.String(140))
     last_seen: so.Mapped[Optional[datetime]] = so.mapped_column(default=lambda: datetime.now(timezone.utc))
+    following: so.WriteOnlyMapped['User'] = so.relationship(
+            secondary=followers,
+            primaryjoin=(followers.c.follower_id == id),
+            secondaryjoin=(followers.c.followed_id == id),
+            back_populates='followers')
+    followers: so.WriteOnlyMapped['User'] = so.relationship(
+            secondary=followers,
+            primaryjoin=(followers.c.followed_id == id),
+            secondaryjoin=(followers.c.follower_id == id),
+            back_populates='following')
 
     def set_password(self, password):
         self.password_hash = generate_password_hash(password)
@@ -49,6 +66,36 @@ class User(UserMixin, db.Model):
         pngloc = os.path.join(basedir, 'usercontent', 'identicon', digest + '.png')
         return pngloc
 
+    def follow(self, user):
+        if not self.is_following(user):
+            self.following.add(user)
+    def unfollow(self, user):
+        if self.is_following(user):
+            self.following.remove(user)
+    def is_following(self, user):
+        query = self.following.select().where(User.id == user.id)
+        return db.session.scalar(query) is not None
+    def followers_count(self):
+        query = sa.select(sa.func.count()).select_from(self.followers.select().subquery())
+        return db.session.scalar(query)
+    def following_count(self):
+        query = sa.select(sa.func.count()).select_from(self.following.select().subquery())
+        return db.session.scalar(query)
+    def following_posts(self):
+        Author = so.aliased(User)
+        Follower = so.aliased(User)
+        return (
+                sa.select(Post)
+                .join(Post.author.of_type(Author))
+                .join(Author.followers.of_type(Follower), isouter=True)
+                .where(sa.or_(
+                    Follower.id == self.id
+                    Author.id == self.id
+                ))
+                .group_by(Post)
+                .order_by(Post.timestamp.desc())
+        )
+
     def __repr__(self):
         return '<User {}>'.format(self.username)