mirror of https://github.com/mitsuhiko/flask.git
Armin Ronacher
13 years ago
32 changed files with 616 additions and 249 deletions
@ -0,0 +1,67 @@ |
|||||||
|
Foreword for Experienced Programmers |
||||||
|
==================================== |
||||||
|
|
||||||
|
This chapter is for programmers who have worked with other frameworks in the |
||||||
|
past, and who may have more specific or esoteric concerns that the typical |
||||||
|
user. |
||||||
|
|
||||||
|
Threads in Flask |
||||||
|
---------------- |
||||||
|
|
||||||
|
One of the design decisions with Flask was that simple tasks should be simple; |
||||||
|
they should not take a lot of code and yet they should not limit you. Because |
||||||
|
of that we made a few design choices that some people might find surprising or |
||||||
|
unorthodox. For example, Flask uses thread-local objects internally so that |
||||||
|
you don’t have to pass objects around from function to function within a |
||||||
|
request in order to stay threadsafe. While this is a really easy approach and |
||||||
|
saves you a lot of time, it might also cause some troubles for very large |
||||||
|
applications because changes on these thread-local objects can happen anywhere |
||||||
|
in the same thread. In order to solve these problems we don’t hide the thread |
||||||
|
locals for you but instead embrace them and provide you with a lot of tools to |
||||||
|
make it as pleasant as possible to work with them. |
||||||
|
|
||||||
|
Web Development is Dangerous |
||||||
|
---------------------------- |
||||||
|
|
||||||
|
If you write a web application, you are probably allowing users to register |
||||||
|
and leave their data on your server. The users are entrusting you with data. |
||||||
|
And even if you are the only user that might leave data in your application, |
||||||
|
you still want that data to be stored securely. |
||||||
|
|
||||||
|
Unfortunately, there are many ways the security of a web application can be |
||||||
|
compromised. Flask protects you against one of the most common security |
||||||
|
problems of modern web applications: cross-site scripting (XSS). Unless |
||||||
|
you deliberately mark insecure HTML as secure, Flask and the underlying |
||||||
|
Jinja2 template engine have you covered. But there are many more ways to |
||||||
|
cause security problems. |
||||||
|
|
||||||
|
The documentation will warn you about aspects of web development that |
||||||
|
require attention to security. Some of these security concerns |
||||||
|
are far more complex than one might think, and we all sometimes underestimate |
||||||
|
the likelihood that a vulnerability will be exploited - until a clever |
||||||
|
attacker figures out a way to exploit our applications. And don't think |
||||||
|
that your application is not important enough to attract an attacker. |
||||||
|
Depending on the kind of attack, chances are that automated bots are |
||||||
|
probing for ways to fill your database with spam, links to malicious |
||||||
|
software, and the like. |
||||||
|
|
||||||
|
So always keep security in mind when doing web development. |
||||||
|
|
||||||
|
The Status of Python 3 |
||||||
|
---------------------- |
||||||
|
|
||||||
|
Currently the Python community is in the process of improving libraries to |
||||||
|
support the new iteration of the Python programming language. While the |
||||||
|
situation is greatly improving there are still some issues that make it |
||||||
|
hard for us to switch over to Python 3 just now. These problems are |
||||||
|
partially caused by changes in the language that went unreviewed for too |
||||||
|
long, partially also because we have not quite worked out how the lower- |
||||||
|
level API should change to account for the Unicode differences in Python 3. |
||||||
|
|
||||||
|
Werkzeug and Flask will be ported to Python 3 as soon as a solution for |
||||||
|
the changes is found, and we will provide helpful tips how to upgrade |
||||||
|
existing applications to Python 3. Until then, we strongly recommend |
||||||
|
using Python 2.6 and 2.7 with activated Python 3 warnings during |
||||||
|
development. If you plan on upgrading to Python 3 in the near future we |
||||||
|
strongly recommend that you read `How to write forwards compatible |
||||||
|
Python code <http://lucumr.pocoo.org/2011/1/22/forwards-compatible-python/>`_. |
||||||
@ -0,0 +1,49 @@ |
|||||||
|
# -*- coding: utf-8 -*- |
||||||
|
""" |
||||||
|
flask.exceptions |
||||||
|
~~~~~~~~~~~~ |
||||||
|
|
||||||
|
Flask specific additions to :class:`~werkzeug.exceptions.HTTPException` |
||||||
|
|
||||||
|
:copyright: (c) 2011 by Armin Ronacher. |
||||||
|
:license: BSD, see LICENSE for more details. |
||||||
|
""" |
||||||
|
from werkzeug.exceptions import HTTPException, BadRequest |
||||||
|
from .helpers import json |
||||||
|
|
||||||
|
|
||||||
|
class JSONHTTPException(HTTPException): |
||||||
|
"""A base class for HTTP exceptions with ``Content-Type: |
||||||
|
application/json``. |
||||||
|
|
||||||
|
The ``description`` attribute of this class must set to a string (*not* an |
||||||
|
HTML string) which describes the error. |
||||||
|
|
||||||
|
""" |
||||||
|
|
||||||
|
def get_body(self, environ): |
||||||
|
"""Overrides :meth:`werkzeug.exceptions.HTTPException.get_body` to |
||||||
|
return the description of this error in JSON format instead of HTML. |
||||||
|
|
||||||
|
""" |
||||||
|
return json.dumps(dict(description=self.get_description(environ))) |
||||||
|
|
||||||
|
def get_headers(self, environ): |
||||||
|
"""Returns a list of headers including ``Content-Type: |
||||||
|
application/json``. |
||||||
|
|
||||||
|
""" |
||||||
|
return [('Content-Type', 'application/json')] |
||||||
|
|
||||||
|
|
||||||
|
class JSONBadRequest(JSONHTTPException, BadRequest): |
||||||
|
"""Represents an HTTP ``400 Bad Request`` error whose body contains an |
||||||
|
error message in JSON format instead of HTML format (as in the superclass). |
||||||
|
|
||||||
|
""" |
||||||
|
|
||||||
|
#: The description of the error which occurred as a string. |
||||||
|
description = ( |
||||||
|
'The browser (or proxy) sent a request that this server could not ' |
||||||
|
'understand.' |
||||||
|
) |
||||||
Loading…
Reference in new issue