第 0023 题： 使用 Python 的 Web 框架，做一个 Web 版本 留言簿 应用。

import sqlite3
from flask import Flask, request, session, g, redirect, url_for, abort, render_template, flash
from contextlib import closing
import time

DATABASE = 'guestbook.db'
DEBUG = True
SECRET_KEY = 'development key'

app = Flask(__name__)
app.config.from_object(__name__)

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

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

@app.before_request
def before_request():
g.db = connect_db()

@app.teardown_request
def teardown_request(exception):
db = getattr(g, 'db', None)
if db is not None:
db.close()
g.db.close()

@app.route('/')
def show_entires():
cur = g.db.execute('select name,text,time from entries order by id desc')
entries = [dict(name=row[0], text=row[1], time=row[2]) for row in cur.fetchall()]
for i in entries:
print i
return render_template('show_entries.html', entries=entries)

@app.route('/add', methods=['POST'])
def add_entry():
if not session.get('logged_in'):
abort(401)
current_time = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())
g.db.execute('insert into entries (name, text, time) values (?, ?, ?)',
[request.form['name'], request.form['text'], current_time])
g.db.commit()
flash('New entry was successfully posted')
return redirect(url_for('show_entires'))

@app.route('/login', methods=['GET', 'POST'])
def login():
error = None
if request.method == 'POST':
if request.form['username'] is None:
error = "Invalid username"
else:
session['logged_in'] = True
session['name'] = request.form['username']
flash('You were logged in')
return redirect(url_for('show_entires'))
return render_template('login.html', error=error)

@app.route('/logout')
def logout():
session.pop('logged_in', None)
flash('You were logged out')
return redirect(url_for('show_entires'))

if __name__ == "__main__":
app.run()