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move note about next param, add example, other cleanup

pull/1871/merge
David Lord 8 years ago
parent
commit
169a4e0c44
  1. 32
      docs/patterns/viewdecorators.rst

32
docs/patterns/viewdecorators.rst

@ -16,15 +16,13 @@ Login Required Decorator
------------------------
So let's implement such a decorator. A decorator is a function that
returns a function. Pretty simple actually. The only thing you have to
keep in mind when implementing something like this is to update the
`__name__`, `__module__` and some other attributes of a function. This is
often forgotten, but you don't have to do that by hand, there is a
function for that that is used like a decorator (:func:`functools.wraps`).
wraps and replaces another function. Since the original function is
replaced, you need to remember to copy the original function's information
to the new function. Use :func:`functools.wraps` to handle this for you.
This example assumes that the login page is called ``'login'`` and that
the current user is stored as `g.user` and ``None`` if there is no-one
logged in::
the current user is stored in ``g.user`` and is ``None`` if there is no-one
logged in. ::
from functools import wraps
from flask import g, request, redirect, url_for
@ -37,20 +35,24 @@ logged in::
return f(*args, **kwargs)
return decorated_function
So how would you use that decorator now? Apply it as innermost decorator
to a view function. When applying further decorators, always remember
that the :meth:`~flask.Flask.route` decorator is the outermost.
While the ``next`` value may exist in ``request.args`` after a ``GET`` request for
the login form, you'll have to pass it along when sending the ``POST`` request
from the login form. You can do this with a hidden input tag and ``requests.values``
or ``requests.form``.::
To use the decorator, apply it as innermost decorator to a view function.
When applying further decorators, always remember
that the :meth:`~flask.Flask.route` decorator is the outermost. ::
@app.route('/secret_page')
@login_required
def secret_page():
pass
.. note::
The ``next`` value will exist in ``request.args`` after a ``GET`` request for
the login page. You'll have to pass it along when sending the ``POST`` request
from the login form. You can do this with a hidden input tag, then retrieve it
from ``request.form`` when logging the user in. ::
<input type="hidden" value="{{ request.args.get('next', '') }}"/>
Caching Decorator
-----------------

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