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编程100小时挑战

利用Flask创建一个mini微博(2)

利用Flask创建一个mini微博(1)

Step 3：创建视图函数

用户登录首页时会进行判断，如果是登录用户则显示，用户关注的时间线，如果没登录则显示公共的时间线。

在首页会有登录登出的选项，这个具体的选项会根据目前用户状态进行判断。如果是未登录则点击进入登录页面，登录成功后返回用户关注的时间线。如果用户已登录，则显示登出，登出后返回公共时间线。

如果是未登录状态，首页还会有注册选项。点击进入注册页面，注册成功后跳转至登录页面。

其次登录用户还可以进入特定的其他用户界面，以浏览某用户的全部微博。在用户的个人界面，可以选择关注或者取消关注某用户。并且可以查看该用户的关注列表。

  • 在处理每个请求前，判断用户是否已登录
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    @app.before_request
    def before_request():
        g.user = None
        if 'user_id' in session:
            g.user = query_db('select * from users where user_id = ?',
                              [session['user_id']], one=True)

通过分析，我们得知在整个网站中需要用到一下链接和对应的视图函数：

  • 首页。

当用户进入首页时判断用户是否登录，如果登录则显示个人的时间线，以显示自己和关注人的消息。否则重定向到公开时间线。

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from flask import session, render_template, redirect, url_for

PER_PAGE = 20

@app.route('/')
def timeline():
    if not g.user:
        return redirect(url_for('public_timeline'))
    query = '''
        SELECT messages.*, users.* FROM messages, users
        WHERE messages.user_id = users.user_id AND (
            users.user_id = ? OR
            users.user_id IN (SELECT followed_id FROM follows
                WHERE follower_id = ?))
        ORDER BY messages.pub_time DESC LIMIT ?'''
    messages = query_db(query, [session['user_id'], session['user_id'], PER_PAGE])
    return  render_template('timeline.html', messages=messages)
  • 公共主页

公共时间线显示最近发布的若干条信息。

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@app.route('/public')
def public_timeline():
    query = '''
        SELECT messages.*, users.* FROM messages, users
        WHERE messages.user_id = users.user_id
        ORDER BY messages.pub_time DESC LIMIT ?'''
    messages = query_db(query, [PER_PAGE])
    return render_template('timeline.html', messages=messages)
  • 用户页

用户页用以显示单个用户发布的所有消息。

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from flask import abort

@app.route('/<username>')
def user_timeline(username):
    profile_user = query_db('SELECT * FROM user WHERE user_name = ?',
        [username], one=True)
    if profile_user is None:
        abort(404)
    followed = False
    if g.user:
        followed = query_db('''SELECT 1 FROM follows WHERE
            follows.follower_id = ? AND follows.followed_id = ?''',
            [session['user_id'], profile_user['user_id']],
            one=True) is not None
    query = '''
        SELECT messages.*, users.* FROM messages, users
        WHERE users.user_id = message.user_id AND users.user_id = ?
        ORDER BY messages.pub_time DESC LIMIT ?'''
    messages = query_db(query, [profile_user[user_id], PER_PAGE])
    return render_template('timeline.html', messages=messages,
        followed=followed, profile_user=profile_user)
  • 关注

关注用户，就是在关注表中添加一条记录，关注人为当前登录用户，被关注者为浏览的用户。

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from flask import flash

@app.route('/<username>/follow')
def follow(username):
    if not g.user:
        abort(401)
    followed_id = get_user_id(username)
    if followed_id is None:
        abort(404)
    db = get_db()
    db.execute('''INSERT INTO follows (follower_id, followed_id)
        VALUES (?, ?)''', [session['user_id'], followed_id])
    db.commit()
    flash('Your are now following "%s".' % username)
    return redirect(url_for('user_timeline', username=username))
  • 取消关注
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@app.route('/<username>/unfollow')
def unfollow(username):
    if not g.user:
        abort(401)
    followed_id = get_user_id(username)
    if followed_id is None:
        abort(404)
    db = get_db()
    db.execute('DELETE FROM follows WHERE follower_id=? AND followed_id=?',
        [session['user_id'], followed_id])
    db.commit()
    flash('You are no longer following "%s".' % username)
    return redirect(url_for('user_timeline', username=username))
  • 发布消息
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import time
from flask import request

@app.route('/add_message', methods=['POST'])
def add_message():
    if not g.user:
        abort(401)
    if request.form['text']:
        db = get_db()
        db.execute('''INSERT INTO messages (user_id, text, pub_time)
            VALUES (?, ?, ?)''', [session['user_id'], request.form['text'],
            int(time.time())])
        db.commit()
        flash('Your message was recorded.')
    return redirect(url_for('timeline'))
  • 注册

注册时，首先要检查用户的提交的信息是否完整，其次检查是否重名。为了安全起见，我们用werkzeug库提供的函数，对密码进行哈希处理，避免在数据库中明文存储密码。

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from werkzeug import generate_password_hash

@app.route('/register', methods=['GET', 'POST'])
def register():
    if g.user:
        return redirect(url_for('timeline'))
    error = None
    if request.method == 'POST':
        if not request.form['username']:
            error = 'You have to enter a username'
        elif not request.form['email'] or \
                '@' not in request.form['email']:
            error = 'You have to enter a valid emial address'
        elif not request.form['password']:
            error = 'You have to enter a password'
        elif request.form['password'] != request.form['password2']:
            error = 'The two password do not match'
        elif get_user_id(request.form['username']) is not None:
            error = 'The username is already taken'
        else:
            db = get_db()
            db.execute('''INSERT INTO users (user_name, email, pw_hash) VALUES
                (?, ?, ?)''', [request.form['username'], request.form['email'], generate_password_hash(request.form['password'])])
            db.commit()
            flash('You were successfully registered and can login now')
            return redirect(url_for('login'))
    if error:
        flash(error)
    return render_template('register.html')
  • 登录
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from werkzeug import check_password_hash

@app.route('/login', methods=['GET', 'POST'])
def login():
    if g.user:
        return redirect(url_for('timeline'))
    error = None
    if request.method == 'POST':
        user = query_db('''SELECT * FROM users WHERE user_name=?''',
            [request.form['username']], one=True)
        if user is None:
            error = 'Invalid username'
        elif not check_password_hash(user['pw_hash'], request.form['password']):
            error = 'Invalid password'
        else:
            flash('You were logged in.')
            session['user_id'] = user['user_id']
            return redirect(url_for('timeline'))
    if error:
        flash(error)
    return render_template('login.html')
  • 登出
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@app.route('/logout')
def logout():
    flash('You were logged out')
    session.pop('user_id', None)
    return redirect(url_for('public_timeline'))
  • 查看关注列表

通过关注列表，用户可以获取与自己有关的关注信息，包括自己关注的人，和关注自己的人。

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@app.route('/follow_list')
def follow_list():
    if not g.user:
        abort(401)
    followed = query_db('SELECT * FROM follows WHERE follower_id=?',
        [session['user_id']])
    follower = query_db('SELECT * FROM follows WHERE followed_id=?',
        [session['user_id']])
    return render_template('follow_list.html', followed=followed, follower=follower)

待续

Step 4：制作模板

Step 5：测试程序

Step 6: 部署程序

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淡定，耐心，积累。创造完整的作品。 编程100小时的挑战，旨在一个月内(2016/6/23开始),用100小时提高编程水平。 目标-行动-记录-改进。

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