Flask初步学习

Flask文档  http://docs.jinkan.org/docs/flask/index.html

快速入门：http://docs.jinkan.org/docs/flask/tutorial/introduction.html

文件目录

schema.sql 

drop table if exists entries;
create table entries (
  id integer primary key autoincrement,
  title string not null,
  text string not null
);

flaskr.py

#!/usr/bin/python
# -*- coding: UTF-8 -*-
"""
-------------------------------------------------
   File Name：     flaskr
   Author :       zhang
   date：          2020/2/12
-------------------------------------------------
"""
# all the imports
import os
import sqlite3

from flask import Flask, request, session, g, redirect, url_for, abort, \
    render_template, flash

DATABASE = './flaskr.db'
DEBUG = True
SECRET_KEY = 'flask flask flask'
USERNAME = 'admin'
PASSWORD = 'password'

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

def connect_db():
    """Connects to the specific database."""
    rv = sqlite3.connect(app.config['DATABASE'])
    rv.row_factory = sqlite3.Row
    return rv

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

#全局变量g.db没有定义，在系统启动前增加全局变量即可
@app.before_request
def before_request():
    g.db = connect_db()

@app.teardown_request
def teardown_request(exception):
    g.db.close()

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

@app.route('/add', methods=['POST'])
def add_entry():
    if not session.get('logged_in'):
        abort(401)
    g.db.execute('insert into entries (title, text) values (?, ?)',
                 [request.form['title'], request.form['text']])
    g.db.commit()
    flash('New entry was successfully posted')
    return redirect(url_for('show_entries'))

@app.route('/login', methods=['GET', 'POST'])
def login():
    error = None
    if request.method == 'POST':
        if request.form['username'] != app.config['USERNAME']:
            error = 'Invalid username'
        elif request.form['password'] != app.config['PASSWORD']:
            error = 'Invalid password'
        else:
            session['logged_in'] = True
            flash('You were logged in')
            return redirect(url_for('show_entries'))
    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_entries'))

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

layout.html

  
Flaskr
  

  {% if not session.logged_in %}
    log in
  {% else %}
    log out
  {% endif %}
  
  {% for message in get_flashed_messages() %}
    
{{ message }}
  {% endfor %}
  {% block body %}{% endblock %}

show_entries.html

{% extends "layout.html" %}
{% block body %}
  {% if session.logged_in %}
    

      

        
Title:
        

        
Text:
        

        

      
    
  {% endif %}
  

  {% for entry in entries %}
    
{{ entry.title }}
{{ entry.text|safe }}
  {% else %}
    
Unbelievable.  No entries here so far
  {% endfor %}
  
{% endblock %}

login.html

{% extends "layout.html" %}
{% block body %}
  
Login
  {% if error %}
Error: {{ error }}{% endif %}
  

    

      
Username:
      

      
Password:
      

      

    
  
{% endblock %}

style.css

body            { font-family: sans-serif; background: #eee; }
a, h1, h2       { color: #377BA8; }
h1, h2          { font-family: 'Georgia', serif; margin: 0; }
h1              { border-bottom: 2px solid #eee; }
h2              { font-size: 1.2em; }

.page           { margin: 2em auto; width: 35em; border: 5px solid #ccc;
                  padding: 0.8em; background: white; }
.entries        { list-style: none; margin: 0; padding: 0; }
.entries li     { margin: 0.8em 1.2em; }
.entries li h2  { margin-left: -1em; }
.add-entry      { font-size: 0.9em; border-bottom: 1px solid #ccc; }
.add-entry dl   { font-weight: bold; }
.metanav        { text-align: right; font-size: 0.8em; padding: 0.3em;
                  margin-bottom: 1em; background: #fafafa; }
.flash          { background: #CEE5F5; padding: 0.5em;
                  border: 1px solid #AACBE2; }
.error          { background: #F0D6D6; padding: 0.5em; }