Add http application for chapter 2

bapleliu · Jun 12, 2018 · d84c891 · d84c891
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diff --git a/demos/http/.flaskenv b/demos/http/.flaskenv
@@ -0,0 +1 @@
+FLASK_ENV=development
diff --git a/demos/http/app.py b/demos/http/app.py
@@ -0,0 +1,214 @@
+# -*- coding: utf-8 -*-
+import os
+try:
+    from urlparse import urlparse, urljoin
+except ImportError:
+    from urllib.parse import urlparse, urljoin
+
+from jinja2 import escape
+from jinja2.utils import generate_lorem_ipsum
+from flask import Flask, make_response, request, redirect, url_for, abort, session, jsonify
+
+app = Flask(__name__)
+app.secret_key = os.getenv('SECRET_KEY', 'secret string')
+
+
+# get name value from query string and cookie
+@app.route('/')
+@app.route('/hello')
+def hello():
+    name = request.args.get('name')
+    if name is None:
+        name = request.cookies.get('name', 'Human')
+    response = '<h1>Hello, %s!</h1>' % escape(name)  # escape name to avoid XSS
+    # return different response according to the user's authentication status
+    if 'logged_in' in session:
+        response += '[Authenticated]'
+    else:
+        response += '[Not Authenticated]'
+    return response
+
+
+# redirect
+@app.route('/hi')
+def hi():
+    return redirect(url_for('hello'))
+
+
+# use int URL converter
+@app.route('/goback/<int:year>')
+def go_back(year):
+    return 'Welcome to %d!' % (2018 - year)
+
+
+# use any URL converter
+@app.route('/colors/<any(blue, white, red):color>')
+def three_colors(color):
+    return '<p>Love is patient and kind. Love is not jealous or boastful or proud or rude.</p>'
+
+
+# return error response
+@app.route('/brew/<drink>')
+def teapot(drink):
+    if drink == 'coffee':
+        abort(418)
+    else:
+        return 'A drop of tea.'
+
+
+# 404
+@app.route('/404')
+def not_found():
+    abort(404)
+
+
+# return response with different formats
+@app.route('/note', defaults={'content_type': 'text'})
+@app.route('/note/<content_type>')
+def note(content_type):
+    content_type = content_type.lower()
+    if content_type == 'text':
+        body = '''Note
+to: Peter
+from: Jane
+heading: Reminder
+body: Don't forget the party!
+'''
+        response = make_response(body)
+        response.mimetype = 'text/plain'
+    elif content_type == 'html':
+        body = '''<!DOCTYPE html>
+<html>
+<head></head>
+<body>
+  <h1>Note</h1>
+  <p>to: Peter</p>
+  <p>from: Jane</p>
+  <p>heading: Reminder</p>
+  <p>body: <strong>Don't forget the party!</strong></p>
+</body>
+</html>
+'''
+        response = make_response(body)
+        response.mimetype = 'text/html'
+    elif content_type == 'xml':
+        body = '''<?xml version="1.0" encoding="UTF-8"?>
+<note>
+  <to>Peter</to>
+  <from>Jane</from>
+  <heading>Reminder</heading>
+  <body>Don't forget the party!</body>
+</note>
+'''
+        response = make_response(body)
+        response.mimetype = 'application/xml'
+    elif content_type == 'json':
+        body = {"note": {
+            "to": "Peter",
+            "from": "Jane",
+            "heading": "Remider",
+            "body": "Don't forget the party!"
+        }
+        }
+        response = jsonify(body)
+        # equal to:
+        # response = make_response(json.dumps(body))
+        # response.mimetype = "application/json"
+    else:
+        abort(400)
+    return response
+
+
+# set cookie
+@app.route('/set/<name>')
+def set_cookie(name):
+    response = make_response(redirect(url_for('hello')))
+    response.set_cookie('name', name)
+    return response
+
+
+# log in user
+@app.route('/login')
+def login():
+    session['logged_in'] = True
+    return redirect(url_for('hello'))
+
+
+# protect view
+@app.route('/admin')
+def admin():
+    if 'logged_in' not in session:
+        abort(403)
+    return 'Welcome to admin page.'
+
+
+# log out user
+@app.route('/logout')
+def logout():
+    if 'logged_in' in session:
+        session.pop('logged_in')
+    return redirect(url_for('hello'))
+
+
+# AJAX
+@app.route('/post')
+def show_post():
+    post_body = generate_lorem_ipsum(n=2)
+    return '''
+<h1>A very long post</h1>
+<div class="body">%s</div>
+<button id="load">Load More</button>
+<script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
+<script type="text/javascript">
+$(function() {
+    $('#load').click(function() {
+        $.ajax({
+            url: '/more',
+            type: 'get',
+            success: function(data){
+                $('.body').append(data);
+            }
+        })
+    })
+})
+</script>''' % post_body
+
+
+@app.route('/more')
+def load_post():
+    return generate_lorem_ipsum(n=1)
+
+
+# redirect to last page
+@app.route('/foo')
+def foo():
+    return '<h1>Foo page</h1><a href="%s">Do something and redirect</a>' \
+           % url_for('do_something', next=request.full_path)
+
+
+@app.route('/bar')
+def bar():
+    return '<h1>Bar page</h1><a href="%s">Do something and redirect</a>' \
+           % url_for('do_something', next=request.full_path)
+
+
+@app.route('/do-something')
+def do_something():
+    # do something here
+    return redirect_back()
+
+
+def is_safe_url(target):
+    ref_url = urlparse(request.host_url)
+    test_url = urlparse(urljoin(request.host_url, target))
+    return test_url.scheme in ('http', 'https') and \
+           ref_url.netloc == test_url.netloc
+
+
+def redirect_back(default='hello', **kwargs):
+    for target in request.args.get('next'), request.referrer:
+        if not target:
+            continue
+        if is_safe_url(target):
+            return redirect(target)
+    return redirect(url_for(default, **kwargs))