Flask学习笔记 8 - 关注和取消关注
Flask教程：http://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-viii-followers-contacts-and-friends
这次课首先介绍了数据库关系，一对一，一对多，多对多。讲得非常明白。查看原文。
模块设置
创建user引用自己的协表followers
模式编码： app/models.py
followers表
followers = db.Table('followers',
db.Column('follower_id', db.Integer, db.ForeignKey('user.id')),
db.Column('followed_id', db.Integer, db.ForeignKey('user.id'))
)
User表
#...
followed = db.relationship('User',
secondary=followers,
primaryjoin=(followers.c.follower_id == id),
secondaryjoin=(followers.c.followed_id == id),
backref=db.backref('followers', lazy='dynamic'),
lazy='dynamic')
def follow(self, user):
if not self.is_following(user):
self.followed.append(user)
return self
def unfollow(self, user):
if self.is_following(user):
self.followed.remove(user)
return self
def is_following(self, user):
return self.followed.filter(followers.c.followed_id == user.id).count() > 0
def followed_posts(self):
return Post.query.join(followers, (followers.c.followed_id == Post.user_id)).filter(followers.c.follower_id == self.id).order_by(Post.timestamp.desc())
运行db_migrate.py更新数据库
客户端实现
首先，新用户自己关注自己添加打开用户页面的链接app/views.py
@oid.after_login
def after_login(resp):
if resp.email is None or resp.email == "":
flash('Invalid login. Please try again.')
return redirect(url_for('login'))
user = User.query.filter_by(email=resp.email).first()
if user is None:
nickname = resp.nickname
if nickname is None or nickname == "":
nickname = resp.email.split('@')[0]
nickname = User.make_unique_nickname(nickname)
user = User(nickname=nickname, email=resp.email)
db.session.add(user)
db.session.commit()
# make the user follow him/herself
db.session.add(user.follow(user))
db.session.commit()
#...
关注和取消关注的控制器app/views.py
@app.route('/follow/<nickname>')
@login_required
def follow(nickname):
user = User.query.filter_by(nickname=nickname).first()
if user is None:
flash('User %s not found.' % nickname)
return redirect(url_for('index'))
if user == g.user:
flash('You can\'t follow yourself!')
return redirect(url_for('user', nickname=nickname))
u = g.user.follow(user)
if u is None:
flash('Cannot follow ' + nickname + '.')
return redirect(url_for('user', nickname=nickname))
db.session.add(u)
db.session.commit()
flash('You are now following ' + nickname + '!')
return redirect(url_for('user', nickname=nickname))
@app.route('/unfollow/<nickname>')
@login_required
def unfollow(nickname):
user = User.query.filter_by(nickname=nickname).first()
if user is None:
flash('User %s not found.' % nickname)
return redirect(url_for('index'))
if user == g.user:
flash('You can\'t unfollow yourself!')
return redirect(url_for('user', nickname=nickname))
u = g.user.unfollow(user)
if u is None:
flash('Cannot unfollow ' + nickname + '.')
return redirect(url_for('user', nickname=nickname))
db.session.add(u)
db.session.commit()
flash('You have stopped following ' + nickname + '.')
return redirect(url_for('user', nickname=nickname))
最后在用户页面中添加关注和取消关注链接 app/templates/user.html
<table>
<tr valign="top">
<td><img src="{{ user.avatar(128) }}"></td>
<td>
<h1>User: {{ user.nickname }}</h1>
{% if user.about_me %}<p>{{ user.about_me }}</p>{% endif %}
{% if user.last_seen %}<p><i>Last seen on: {{ user.last_seen }}</i></p>{% endif %}
<p>{{ user.followers.count() }} followers |
{% if user.id == g.user.id %}
<a href="{{ url_for('edit') }}">Edit your profile</a>
{% elif not g.user.is_following(user) %}
<a href="{{ url_for('follow', nickname=user.nickname) }}">Follow</a>
{% else %}
<a href="{{ url_for('unfollow', nickname=user.nickname) }}">Unfollow</a>
{% endif %}
</p>
</td>
</tr>
</table>