Adds Injector support to Flask, this way there's no need to use global Flask objects, which makes testing simpler.
Injector is a dependency-injection framework for Python, inspired by Guice.
Flask-Injector is compatible with CPython 2.6-2.7, 3.3+ and PyPy 1.9+. As of version 0.3.0 it requires Injector version 0.7.4 or greater.
GitHub project page: https://github.com/alecthomas/flask_injector
PyPI package page: https://pypi.python.org/pypi/Flask-Injector
Changelog: https://github.com/alecthomas/flask_injector/blob/master/CHANGELOG.rst
Flask-Injector lets you inject dependencies into:
- views (functions and class-based)
- before_request handlers
- after_request handlers
- teardown_request handlers
- template context processors
- error handlers
- Jinja environment globals (functions in app.jinja_env.globals)
import sqlite3
from flask import Flask, Config
from flask.views import View
from flask_injector import FlaskInjector
from injector import inject
app = Flask(__name__)
# Configure your application by attaching views, handlers, context processors etc.:
@app.route("/bar")
def bar():
return render("bar.html")
# Route with injection
@app.route("/foo")
@inject(db=sqlite3.Connection)
def foo(db):
users = db.execute('SELECT * FROM users').all()
return render("foo.html")
# Class-based view with injected constructor
class Waz(View):
@inject(db=sqlite3.Connection)
def __init__(self, db):
self.db = db
def dispatch_request(self, key):
users = self.db.execute('SELECT * FROM users WHERE name=?', (key,)).all()
return 'waz'
app.add_url_rule('/waz/<key>', view_func=Waz.as_view('waz'))
# In the Injector world, all dependency configuration and initialization is
# performed in modules (http://packages.python.org/injector/#module). The
# same is true with Flask-Injector. You can see some examples of configuring
# Flask extensions through modules below.
# Accordingly, the next step is to create modules for any objects we want made
# available to the application. Note that in this example we also use the
# Injector to gain access to the `flask.Config`:
def configure(binder):
binder.bind(
sqlite3.Connection,
to=sqlite3.Connection(':memory:'),
scope=request,
)
# Initialize Flask-Injector. This needs to be run *after* you attached all
# views, handlers, context processors and template globals.
FlaskInjector(app=app, modules=[configure])
# All that remains is to run the application
app.run()See example.py for a more complete example, including Flask-SQLAlchemy and Flask-Cache integration.
Typically, Flask extensions are initialized at the global scope using a pattern similar to the following.
app = Flask(__name__)
ext = ExtClass(app)
@app.route(...)
def view():
# Use ext object here...As we don't have these globals with Flask-Injector we have to configure the extension the Injector way - through modules. Modules can either be subclasses of injector.Module or a callable taking an injector.Binder instance.
@inject(app=Flask)
def configure_ext(binder, app):
binder.bind(ExtClass, to=ExtClass(app), scope=singleton)
def main():
app = Flask(__name__)
app.config.update(
EXT_CONFIG_VAR='some_value',
)
# attach your views etc. here
FlaskInjector(app=app, modules=[configure_ext])
app.run()Make sure to bind extension objects as singletons.