FlaskWarts 0.1a7

Assortment of various utilities for Flask applications

FlaskWarts are a set of utility classes and functions for making it easier to overcome some of the warts that one always seem to encounter when developing Flask applications. It’s called ‘warts’ because ‘utils’ was taken. The main package is still called utils, because that’s what it was called in a few apps author was using the code in, and was too lazy to refactor them all.

Overview

The library is not too generic. In fact, it’s quite opinionated. It’s made available as is if you care to use it, but it’s mainly there for the author’s use cases.

While not an immediate goal, it is author’s intention to make this a fully-comliant Flask extension at some point, and far more flexible. It may be brokend down into multiple separate libraries as well. Currently, it is a multi-purpose library that expects you to organize your site as a single application and uses flask.current_app extensively. While this is not a good pattern in general, it’s a pattern that works (for the time being).

It also expects that you place your configuration in app.config.

Note that not all code is fully developed and tested. Some of the code even misses unit tests, and documentation doesn’t exist. So this is pretty much pre-alpha software. Also, don’t expect anything in the way of API stability in any form.

Features

The utils have following features:

• Class-based route handlers (utils.routes)

• Form-handling with Formencode (utils.forms)

• CSRF middleware (utils.middlewares)

• Basic timezone manipulation support (utils.timezone)

• One decorator for denying non-XHR requests (utils.decorators)

Installation

Either:

easy_install FlaskWarts

Or:

pip install FlaskWarts

Class-based route handling

Please see the sources for now. More detailed docs are planned for future releases. It’s similar to Django’s CBVs but not quite the same.

Simple example:

from flask import render_template
from utils.routes import Route

class MyRoute(Route):
    path = '/my'

    def GET(self):
        return render_template('foo.html')

Method names correspond to HTTP methods, and any positional or keyword arguments in the paths are passed as positional and keyword arguments to the method. In addition, the positional and keyword arguments are accessible as self.args and self.kwargs, a list and dict respectively.

Methods are expected to return a response just like normal flask route handler functions.

By default, HTTP method overrides are supported via the _method request parameter for all POST requests, and the Route class intelligently maps them to the correct instance method. This is handled transparently behind the scenes so you don’t have to worry about it. You can disable this behavior, by setting the allow_overrides property to False in your subclass.

There are many subclasses of the Route class which implement different interfaces for common tasks like form processing and template rendering. Some of them implement multiple HTTP methods. For now you will have to look at the sources to find out more.

Routes are reigstered by calling the register() class method, and passing it an application object:

MyRoute.register(app)

The route name can be explicitly specified using the name property. Otherwise, it is derived from the class name by decamelizing it. For instance, MyRoute has a name of my_route. Foo has a name of foo, and so on.

If you organize routes into modules (e.g., have multiple route classes in a single module), you can register them in batches.

from utils.routes import register_module
register_module(app, 'myapp.routes')

The register_module() function will register any object that has register() and get_route_name() attributes, and whose path attribute is not None. This is generally a good enough set of rules to catch all routes, but if you have objects that accidentally fulfill the conditions, the function will try to register it, so be careful.

If you want to explicitly exlude routes, you can use the exclude argument. This argument should be an iterable containing names of classes or route names.

For instance:

register_module(app, 'myapp.routes', exclude=['Test', 'mickey_mouse'])

The above excludes classes Test and MickeyMouse.

Form-handling with Formencode

Allows basic form validation using Formencode’s htmlfill_schemabuilder. Docs on the way, so stay tuned.

CSRF middleware

A bit rough at the moment, but works. Uses os.urandom for random number generation, you’ve been warned. It also makes Jinja2 a requirement.

Basic usage is simply:

from utils.middlewares import csrf
csrf(app)

In template:

<form method="POST">
    {{ csrf_tag }}
    ...
</form>

Docs? Who said anything about docs? :D

Timezone manipulation

Requires pytz. Again, no docs yet, so please look at the module.

Decorators

To prevent non-XHR requests to your endpoint, just do this:

from utils.decorators import xhr_only

@app.route('/')
@xhr_only
def my_view():
    pass

It will abort a non-XHR request with HTTP 400 status.