Flask -- 使用数据库(Sqlite3)、用户注册、登录注销、修改密码

---

# 使用sqlite数据库

import sqlite3
from contextlib import closing

app.config.update(
    DATABASE = 'my.db',      #相对于文件所在目录
    DEBUG=True,
)

def connect_db():
    return sqlite3.connect(app.config['DATABASE'])

def init_db():
    with closing(connect_db()) as db:
        with app.open_resource('schema.sql', 'r') as f:
            db.cursor().executescript(f.read())
        db.commit()

def get_db():
    db = connect_db()
    cur = db.cursor()
    return db, cur

---

# 用户注册

　from wtforms import Form, TextField, PasswordField, BooleanField, validators
　from passlib.hash import sha256_crypt

import gc

class RegistrationForm(Form):     使用flask-WTF表单系统，可以方便地使用逻辑（pip install flask-WTF）

    username = TextField('Username', [validators.Length(min=4, max=20)])
    email = TextField('Email', [validators.Length(min=6, max=50)])
    password = PasswordField('Password', [validators.Required(), validators.EqualTo('confirm', message='Passwords must match.')])
    confirm = PasswordField('Password Again')
    accept_tos = BooleanField("<small>I accept it</small>", [validators.Required()])

@app.route('/register/', methods=['POST', 'GET'])
def register():
    try:
        form = RegistrationForm(request.form)

        if request.method == 'POST' and form.validate():
            username = form.username.data
            email = form.email.data
            password = sha256_crypt.encrypt(str(form.password.data))    #对密码加密,生成一个hash值[每次调用生成不同的hash]（pip install passlib)

            db, cur = get_db()

            x = cur.execute(
                'SELECT * FROM users WHERE username = ?', [username])

            if x.fetchall():
                flash("That username is already taken, please choose another")
                return render_template('register.html', form=form)

            else:
                cur.execute("INSERT INTO users (username, password, email) VALUES(?,?,?)", [
                            username, password, email])
                db.commit()

                flash("Thanks for registering!")

                cur.close()
                db.close()
                gc.collect()      # collect garbage

                session['logged_in'] = True
                session['username'] = username

                return redirect(url_for('dashboard'))

        return render_template('register.html', form=form)   

    except Exception as e:
        return str(e)

#register.html

<div class="container" style>
    <h4>Welcome to register</h4>
    <br />
    {% from '_formhelpers.html' import render_field %}
    <form action="" method="post">
        {{ render_field(form.username) }}
        {{ render_field(form.email) }}
        {{ render_field(form.password) }}
        {{ render_field(form.confirm) }}
        {{ render_field(form.accept_tos) }}

        <p><input type="submit" value="Register" /></p>
    </form>

    {% if error %}
        <p class="error"><strong>Error: </strong>{{ error }}</p>
    {% endif %}

</div>

# _formhelper.html

{% macro render_field(field) %}  宏逻辑，相当于一个函数

<dt>{{ field.label }}</dt>
<dd>{{ field(**kwargs) | safe }}
    {% if field.errors  %}
        <ul class="errors">
            {% for error in field.errors %}
            <li>{{ error }}</li>
            {% endfor %}
        </ul>
    {% endif %}
<dd>

{% endmacro %}

#用户登录

@app.route('/login/', methods=['POST', 'GET'])
def login():
    try:
        error = None
        if request.method == 'POST':

            username = request.form['username']
            password = request.form['password']

            db, cur = get_db()

            passwd_hash_tuple = cur.execute(
                'SELECT password FROM users WHERE username=?', [username]).fetchone()   # return a tuple

            if not passwd_hash_tuple:
                error = 'Invalid username'
            elif not sha256_crypt.verify(password, passwd_hash_tuple[0]):
                error = 'Invalid password'
            else:
                flash('Hey %s, you are in' % username)
                session['logged_in'] = True
                session['username'] = username
                return redirect(url_for('dashboard'))

        gc.collect()
        return render_template('login.html', error=error)

    except Exception as e:
        return str(e)

# login.html

<div class="container">
    {% if error %}
        <p class="alert alert-danger">{{ error }}</p>
    {% endif %}

    <h4>Please Login</h4>
    <form method="post" action="" class="form-inline">
        <input type="text" class="form-control" placeholder="username" name="username" value="{{ request.form.username }}" />
        <input type="password" class="form-control" placeholder="password" name="password" value="{{ request.form.password }}" />
        <input type="submit" class="btn btn-default" value="Login" />
    </form>

</div>

# 用户退出

@app.route('/logout/')
@login_required
def logout():
    session.pop('logged_in', None)
    flash("You have logged out")
    return redirect(url_for('dashboard'))