Added mini blogging application as Flask example.

This should become the tutorial.

examples/flaskr/flaskr.py

@@ -0,0 +1,103 @@
+# -*- coding: utf-8 -*-
+"""
+    Flaskr
+    ~~~~~~
+
+    A microblog example application written as Flask tutorial with
+    Flask and sqlite3.
+
+    :copyright: (c) 2010 by Armin Ronacher.
+    :license: BSD, see LICENSE for more details.
+"""
+from __future__ import with_statement
+import time
+import sqlite3
+from contextlib import closing
+from flask import Flask, request, session, g, redirect, url_for, abort, \
+     render_template, flash
+from werkzeug import secure_filename
+
+# configuration
+DATABASE = '/tmp/flaskr.db'
+DEBUG = True
+SECRET_KEY = 'development key'
+USERNAME = 'admin'
+PASSWORD = 'default'
+
+# create our little application :)
+app = Flask(__name__)
+app.secret_key = SECRET_KEY
+app.debug = DEBUG
+
+
+def connect_db():
+    """Returns a new connection to the database."""
+    return sqlite3.connect(DATABASE)
+
+
+def init_db():
+    """Creates the database tables."""
+    with closing(connect_db()) as db:
+        with app.open_resource('schema.sql') as f:
+            db.cursor().executescript(f.read())
+        db.commit()
+
+
+@app.request_init
+def before_request():
+    """Make sure we are connected to the database each request.  Also
+    set `g.logged_in` to `True` if we are logged in.
+    """
+    g.db = connect_db()
+    g.logged_in = session.get('logged_in', False)
+
+
+@app.request_shutdown
+def after_request(response):
+    """Closes the database again at the end of the request."""
+    g.db.close()
+    return response
+
+
+@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 g.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'] != USERNAME:
+            error = 'Invalid username'
+        elif request.form['password'] != 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()