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Merge pull request #369 from FND/docs 

documentation: stylistic adjustments
pull/375/head
Armin Ronacher 13 years ago
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3 changed files with 79 additions and 80 deletions
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  1. 28
      docs/foreword.rst
  2. 18
      docs/installation.rst
  3. 109
      docs/quickstart.rst

28
docs/foreword.rst
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@ -9,16 +9,16 @@ What does "micro" mean?
----------------------- -----------------------
To me, the "micro" in microframework refers not only to the simplicity and To me, the "micro" in microframework refers not only to the simplicity and
small size of the framework, but also the fact that it does not make much small size of the framework, but also the fact that it does not make many
decisions for you. While Flask does pick a templating engine for you, we decisions for you. While Flask does pick a templating engine for you, we
won't make such decisions for your datastore or other parts. won't make such decisions for your datastore or other parts.
For us however the term “micro” does not mean that the whole implementation However, to us the term “micro” does not mean that the whole implementation
has to fit into a single Python file. has to fit into a single Python file.
One of the design decisions with Flask was that simple tasks should be One of the design decisions with Flask was that simple tasks should be
simple and not take up a lot of code and yet not limit yourself. Because simple; they should not take a lot of code and yet they should not limit you.
of that we took a few design choices that some people might find Because of that we made a few design choices that some people might find
surprising or unorthodox. For example, Flask uses thread-local objects surprising or unorthodox. For example, Flask uses thread-local objects
internally so that you don't have to pass objects around from function to 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 function within a request in order to stay threadsafe. While this is a
@ -30,17 +30,17 @@ and provide you with a lot of tools to make it as pleasant as possible to
work with them. work with them.
Flask is also based on convention over configuration, which means that Flask is also based on convention over configuration, which means that
many things are preconfigured. For example, by convention, templates and many things are preconfigured. For example, by convention templates and
static files are in subdirectories within the Python source tree of the static files are stored in subdirectories within the application's Python source tree.
application. While this can be changed you usually don't have to. While this can be changed you usually don't have to.
The main reason however why Flask is called a "microframework" is the idea The main reason Flask is called a "microframework" is the idea
to keep the core simple but extensible. There is no database abstraction to keep the core simple but extensible. There is no database abstraction
layer, no form validation or anything else where different libraries layer, no form validation or anything else where different libraries
already exist that can handle that. However Flask knows the concept of already exist that can handle that. However Flask supports
extensions that can add this functionality into your application as if it extensions to add such functionality to your application as if it
was implemented in Flask itself. There are currently extensions for was implemented in Flask itself. There are currently extensions for
object relational mappers, form validation, upload handling, various open object-relational mappers, form validation, upload handling, various open
authentication technologies and more. authentication technologies and more.
Since Flask is based on a very solid foundation there is not a lot of code Since Flask is based on a very solid foundation there is not a lot of code
@ -71,7 +71,7 @@ cause security problems.
The documentation will warn you about aspects of web development that The documentation will warn you about aspects of web development that
require attention to security. Some of these security concerns require attention to security. Some of these security concerns
are far more complex than one might think, and we all sometimes underestimate are far more complex than one might think, and we all sometimes underestimate
the likelihood that a vulnerability will be exploited, until a clever the likelihood that a vulnerability will be exploited - until a clever
attacker figures out a way to exploit our applications. And don't think attacker figures out a way to exploit our applications. And don't think
that your application is not important enough to attract an attacker. that your application is not important enough to attract an attacker.
Depending on the kind of attack, chances are that automated bots are Depending on the kind of attack, chances are that automated bots are
@ -88,8 +88,8 @@ support the new iteration of the Python programming language. While the
situation is greatly improving there are still some issues that make it 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 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 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 long, partially also because we have not quite worked out how the lower-
level API should change for the unicode differences in Python3. 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 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 the changes is found, and we will provide helpful tips how to upgrade

18
docs/installation.rst
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@ -9,8 +9,8 @@ Werkzeug is a toolkit for WSGI, the standard Python interface between web
applications and a variety of servers for both development and deployment. applications and a variety of servers for both development and deployment.
Jinja2 renders templates. Jinja2 renders templates.
So how do you get all that on your computer quickly? There are many ways So how do you get all that on your computer quickly? There are many ways,
which this section will explain, but the most kick-ass method is as this section will explain, but the most kick-ass method is
virtualenv, so let's look at that first. virtualenv, so let's look at that first.
Either way, you will need Python 2.5 or higher to get started, so be sure Either way, you will need Python 2.5 or higher to get started, so be sure
@ -58,7 +58,7 @@ even in your package manager. If you use Ubuntu, try::
If you are on Windows and don't have the `easy_install` command, you must If you are on Windows and don't have the `easy_install` command, you must
install it first. Check the :ref:`windows-easy-install` section for more install it first. Check the :ref:`windows-easy-install` section for more
information about how to do that. Once you have it installed, run the information on how to do that. Once you have it installed, run the
same commands as above, but without the `sudo` prefix. same commands as above, but without the `sudo` prefix.
Once you have virtualenv installed, just fire up a shell and create Once you have virtualenv installed, just fire up a shell and create
@ -78,7 +78,7 @@ the corresponding environment. On OS X and Linux, do the following::
(Note the space between the dot and the script name. The dot means that (Note the space between the dot and the script name. The dot means that
this script should run in the context of the current shell. If this command this script should run in the context of the current shell. If this command
does not work in your shell, try replacing the dot with ``source``) does not work in your shell, try replacing the dot with ``source``.)
If you are a Windows user, the following command is for you:: If you are a Windows user, the following command is for you::
@ -95,15 +95,15 @@ your virtualenv::
A few seconds later you are good to go. A few seconds later you are good to go.
System Wide Installation System-Wide Installation
------------------------ ------------------------
This is possible as well, but I do not recommend it. Just run This is possible as well, though I do not recommend it. Just run
`easy_install` with root rights:: `easy_install` with root privileges::
$ sudo easy_install Flask $ sudo easy_install Flask
(Run it in an Admin shell on Windows systems and without `sudo`). (Run it in an Admin shell on Windows systems and without `sudo`.)
Living on the Edge Living on the Edge
@ -159,7 +159,7 @@ to the `PATH` environment variable. To do that, right-click on the
"Computer" icon on the Desktop or in the Start menu, and choose "Computer" icon on the Desktop or in the Start menu, and choose
"Properties". Then, on Windows Vista and Windows 7 click on "Advanced System "Properties". Then, on Windows Vista and Windows 7 click on "Advanced System
settings"; on Windows XP, click on the "Advanced" tab instead. Then click settings"; on Windows XP, click on the "Advanced" tab instead. Then click
on the "Environment variables" button and double click on the "Path" on the "Environment variables" button and double-click on the "Path"
variable in the "System variables" section. There append the path of your variable in the "System variables" section. There append the path of your
Python interpreter's Scripts folder; make sure you delimit it from Python interpreter's Scripts folder; make sure you delimit it from
existing values with a semicolon. Assuming you are using Python 2.6 on existing values with a semicolon. Assuming you are using Python 2.6 on

109
docs/quickstart.rst
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@ -3,7 +3,7 @@
Quickstart Quickstart
========== ==========
Eager to get started? This page gives a good introduction in how to get Eager to get started? This page gives a good introduction on how to get
started with Flask. This assumes you already have Flask installed. If started with Flask. This assumes you already have Flask installed. If
you do not, head over to the :ref:`installation` section. you do not, head over to the :ref:`installation` section.
@ -39,16 +39,16 @@ So what did that code do?
1. First we imported the :class:`~flask.Flask` class. An instance of this 1. First we imported the :class:`~flask.Flask` class. An instance of this
class will be our WSGI application. The first argument is the name of class will be our WSGI application. The first argument is the name of
the application's module. If you are using a single module (like here) the application's module. If you are using a single module (as in this example)
you should use `__name__` because depending on if it's started as you should use `__name__` because depending on whether it's started as
application or imported as module the name will be different application or imported as module the name will be different
(``'__main__'`` versus the actual import name). For more information (``'__main__'`` versus the actual import name). For more information
on that, have a look at the :class:`~flask.Flask` documentation. on this technique, have a look at the :class:`~flask.Flask` documentation.
2. Next we create an instance of it. We pass it the name of the module / 2. Next we create an instance of it. We pass it the name of the module /
package. This is needed so that Flask knows where it should look for package. This is needed so that Flask knows where it should look for
templates, static files and so on. templates, static files and so on.
3. Then we use the :meth:`~flask.Flask.route` decorator to tell Flask 3. Then we use the :meth:`~flask.Flask.route` decorator to tell Flask
what URL should trigger our function. which URL should trigger our function.
4. The function then has a name which is also used to generate URLs to 4. The function then has a name which is also used to generate URLs to
that particular function, and returns the message we want to display in that particular function, and returns the message we want to display in
the user's browser. the user's browser.
@ -63,15 +63,14 @@ To stop the server, hit control-C.
.. admonition:: Externally Visible Server .. admonition:: Externally Visible Server
If you run the server you will notice that the server is only available If you run the server you will notice that the server is only accessible
from your own computer, not from any other in the network. This is the from your own computer, not from any other in the network. This is the
default because in debugging mode a user of the application can execute default because in debugging mode a user of the application can execute
arbitrary Python code on your computer. If you have `debug` disabled arbitrary Python code on your computer.
or trust the users on your network, you can make the server publicly
available.
Just change the call of the :meth:`~flask.Flask.run` method to look If you have `debug` disabled or trust the users on your network, you can
like this:: make the server publicly available simply by changing the call of the
:meth:`~flask.Flask.run` method to look like this::
app.run(host='0.0.0.0') app.run(host='0.0.0.0')
@ -83,9 +82,9 @@ Debug Mode
The :meth:`~flask.Flask.run` method is nice to start a local The :meth:`~flask.Flask.run` method is nice to start a local
development server, but you would have to restart it manually after each development server, but you would have to restart it manually after each
change you do to code. That is not very nice and Flask can do better. If change to your code. That is not very nice and Flask can do better. If
you enable the debug support the server will reload itself on code changes you enable debug support the server will reload itself on code changes,
and also provide you with a helpful debugger if things go wrong. and it will also provide you with a helpful debugger if things go wrong.
There are two ways to enable debugging. Either set that flag on the There are two ways to enable debugging. Either set that flag on the
application object:: application object::
@ -93,7 +92,7 @@ application object::
app.debug = True app.debug = True
app.run() app.run()
Or pass it to run:: Or pass it to `run`::
app.run(debug=True) app.run(debug=True)
@ -123,7 +122,7 @@ Routing
------- -------
Modern web applications have beautiful URLs. This helps people remember Modern web applications have beautiful URLs. This helps people remember
the URLs which is especially handy for applications that are used from the URLs, which is especially handy for applications that are used from
mobile devices with slower network connections. If the user can directly mobile devices with slower network connections. If the user can directly
go to the desired page without having to hit the index page it is more go to the desired page without having to hit the index page it is more
likely they will like the page and come back next time. likely they will like the page and come back next time.
@ -171,8 +170,8 @@ The following converters exist:
.. admonition:: Unique URLs / Redirection Behaviour .. admonition:: Unique URLs / Redirection Behaviour
Flask's URL rules are based on Werkzeug's routing module. The idea Flask's URL rules are based on Werkzeug's routing module. The idea
behind that module is to ensure nice looking and also unique URLs based behind that module is to ensure nice-looking and also unique URLs based
on behaviour Apache and earlier servers coined. on behaviour coined by Apache and earlier servers.
Take these two rules:: Take these two rules::
@ -190,14 +189,14 @@ The following converters exist:
that sense. Accessing it without a trailing slash will cause Flask to that sense. Accessing it without a trailing slash will cause Flask to
redirect to the canonical URL with the trailing slash. redirect to the canonical URL with the trailing slash.
However in the second case the URL is defined without a slash so it However, in the second case the URL is defined without a slash so it
behaves similar to a file and accessing the URL with a trailing slash behaves similar to a file and accessing the URL with a trailing slash
will be a 404 error. will result in a 404 error.
Why is this? This allows relative URLs to continue working if users Why is this? This allows relative URLs to continue working if users
access the page when they forget a trailing slash. This behaviour is access the page when they forget a trailing slash. This behaviour is
also consistent with how Apache and other servers work. Also, the URLs also consistent with how Apache and other servers work. Also, the URLs
will stay unique which helps search engines not indexing the same page will stay unique which ensures search engines do not index the same page
twice. twice.
@ -238,7 +237,7 @@ parameter. Here are some examples:
(This also uses the :meth:`~flask.Flask.test_request_context` method (This also uses the :meth:`~flask.Flask.test_request_context` method
explained below. It basically tells Flask to think we are handling a explained below. It basically tells Flask to think we are handling a
request even though we are not, we are in an interactive Python shell. request even though we are not, we are in an interactive Python shell.
Have a look at the explanation below. :ref:`context-locals`). Have a look at the explanation below: :ref:`context-locals`.)
Why would you want to build URLs instead of hardcoding them in your Why would you want to build URLs instead of hardcoding them in your
templates? There are three good reasons for this: templates? There are three good reasons for this:
@ -270,10 +269,10 @@ that can be changed by providing the `methods` argument to the
If `GET` is present, `HEAD` will be added automatically for you. You If `GET` is present, `HEAD` will be added automatically for you. You
don't have to deal with that. It will also make sure that `HEAD` requests don't have to deal with that. It will also make sure that `HEAD` requests
are handled like the `HTTP RFC`_ (the document describing the HTTP are handled as the `HTTP RFC`_ (the document describing the HTTP
protocol) demands, so you can completely ignore that part of the HTTP protocol) demands, so you can completely ignore that part of the HTTP
specification. Likewise as of Flask 0.6, `OPTIONS` is implemented for you specification. Likewise, as of Flask 0.6, `OPTIONS` is implemented for you
as well automatically. automatically as well.
You have no idea what an HTTP method is? Worry not, here is a quick You have no idea what an HTTP method is? Worry not, here is a quick
introduction to HTTP methods and why they matter: introduction to HTTP methods and why they matter:
@ -297,14 +296,14 @@ very common:
`POST` `POST`
The browser tells the server that it wants to *post* some new The browser tells the server that it wants to *post* some new
information to that URL and that the server must ensure the data is information to that URL and that the server must ensure the data is
stored and only stored once. This is how HTML forms are usually stored and only stored once. This is how HTML forms usually
transmitting data to the server. transmit data to the server.
`PUT` `PUT`
Similar to `POST` but the server might trigger the store procedure Similar to `POST` but the server might trigger the store procedure
multiple times by overwriting the old values more than once. Now you multiple times by overwriting the old values more than once. Now you
might be asking why is this useful, but there are some good reasons might be asking why this is useful, but there are some good reasons
to do it this way. Consider that the connection gets lost during to do it this way. Consider that the connection is lost during
transmission: in this situation a system between the browser and the transmission: in this situation a system between the browser and the
server might receive the request safely a second time without breaking server might receive the request safely a second time without breaking
things. With `POST` that would not be possible because it must only things. With `POST` that would not be possible because it must only
@ -330,13 +329,13 @@ use it.
Static Files Static Files
------------ ------------
Dynamic web applications need static files as well. That's usually where Dynamic web applications also need static files. That's usually where
the CSS and JavaScript files are coming from. Ideally your web server is the CSS and JavaScript files are coming from. Ideally your web server is
configured to serve them for you, but during development Flask can do that configured to serve them for you, but during development Flask can do that
as well. Just create a folder called `static` in your package or next to as well. Just create a folder called `static` in your package or next to
your module and it will be available at `/static` on the application. your module and it will be available at `/static` on the application.
To generate URLs to that part of the URL, use the special ``'static'`` URL To generate URLs that part of the URL, use the special ``'static'`` URL
name:: name::
url_for('static', filename='style.css') url_for('static', filename='style.css')
@ -352,7 +351,7 @@ the application secure. Because of that Flask configures the `Jinja2
<http://jinja.pocoo.org/2/>`_ template engine for you automatically. <http://jinja.pocoo.org/2/>`_ template engine for you automatically.
To render a template you can use the :func:`~flask.render_template` To render a template you can use the :func:`~flask.render_template`
method. All you have to do is to provide the name of the template and the method. All you have to do is provide the name of the template and the
variables you want to pass to the template engine as keyword arguments. variables you want to pass to the template engine as keyword arguments.
Here's a simple example of how to render a template:: Here's a simple example of how to render a template::
@ -364,7 +363,7 @@ Here's a simple example of how to render a template::
return render_template('hello.html', name=name) return render_template('hello.html', name=name)
Flask will look for templates in the `templates` folder. So if your Flask will look for templates in the `templates` folder. So if your
application is a module, that folder is next to that module, if it's a application is a module, this folder is next to that module, if it's a
package it's actually inside your package: package it's actually inside your package:
**Case 1**: a module:: **Case 1**: a module::
@ -405,9 +404,9 @@ know how that works, head over to the :ref:`template-inheritance` pattern
documentation. Basically template inheritance makes it possible to keep documentation. Basically template inheritance makes it possible to keep
certain elements on each page (like header, navigation and footer). certain elements on each page (like header, navigation and footer).
Automatic escaping is enabled, so if name contains HTML it will be escaped Automatic escaping is enabled, so if `name` contains HTML it will be escaped
automatically. If you can trust a variable and you know that it will be automatically. If you can trust a variable and you know that it will be
safe HTML (because for example it came from a module that converts wiki safe HTML (for example because it came from a module that converts wiki
markup to HTML) you can mark it as safe by using the markup to HTML) you can mark it as safe by using the
:class:`~jinja2.Markup` class or by using the ``|safe`` filter in the :class:`~jinja2.Markup` class or by using the ``|safe`` filter in the
template. Head over to the Jinja 2 documentation for more examples. template. Head over to the Jinja 2 documentation for more examples.
@ -442,7 +441,7 @@ For web applications it's crucial to react to the data a client sent to
the server. In Flask this information is provided by the global the server. In Flask this information is provided by the global
:class:`~flask.request` object. If you have some experience with Python :class:`~flask.request` object. If you have some experience with Python
you might be wondering how that object can be global and how Flask you might be wondering how that object can be global and how Flask
manages to still be threadsafe. The answer are context locals: manages to still be threadsafe. The answer is context locals:
.. _context-locals: .. _context-locals:
@ -461,19 +460,19 @@ context. What a mouthful. But that is actually quite easy to understand.
Imagine the context being the handling thread. A request comes in and the Imagine the context being the handling thread. A request comes in and the
web server decides to spawn a new thread (or something else, the web server decides to spawn a new thread (or something else, the
underlying object is capable of dealing with other concurrency systems underlying object is capable of dealing with concurrency systems other
than threads as well). When Flask starts its internal request handling it than threads). When Flask starts its internal request handling it
figures out that the current thread is the active context and binds the figures out that the current thread is the active context and binds the
current application and the WSGI environments to that context (thread). current application and the WSGI environments to that context (thread).
It does that in an intelligent way that one application can invoke another It does that in an intelligent way so that one application can invoke another
application without breaking. application without breaking.
So what does this mean to you? Basically you can completely ignore that So what does this mean to you? Basically you can completely ignore that
this is the case unless you are doing something like unit testing. You this is the case unless you are doing something like unit testing. You
will notice that code that depends on a request object will suddenly break will notice that code which depends on a request object will suddenly break
because there is no request object. The solution is creating a request because there is no request object. The solution is creating a request
object yourself and binding it to the context. The easiest solution for object yourself and binding it to the context. The easiest solution for
unittesting is by using the :meth:`~flask.Flask.test_request_context` unit testing is to use the :meth:`~flask.Flask.test_request_context`
context manager. In combination with the `with` statement it will bind a context manager. In combination with the `with` statement it will bind a
test request so that you can interact with it. Here is an example:: test request so that you can interact with it. Here is an example::
@ -680,8 +679,8 @@ converting return values into response objects is as follows:
default parameters. default parameters.
3. If a tuple is returned the response object is created by passing the 3. If a tuple is returned the response object is created by passing the
tuple as arguments to the response object's constructor. tuple as arguments to the response object's constructor.
4. If neither of that works, Flask will assume the return value is a 4. If none of that works, Flask will assume the return value is a
valid WSGI application and converts that into a response object. valid WSGI application and convert that into a response object.
If you want to get hold of the resulting response object inside the view If you want to get hold of the resulting response object inside the view
you can use the :func:`~flask.make_response` function. you can use the :func:`~flask.make_response` function.
@ -711,8 +710,8 @@ return it:
Sessions Sessions
-------- --------
Besides the request object there is also a second object called In addition to the request object there is also a second object called
:class:`~flask.session` that allows you to store information specific to a :class:`~flask.session` which allows you to store information specific to a
user from one request to the next. This is implemented on top of cookies user from one request to the next. This is implemented on top of cookies
for you and signs the cookies cryptographically. What this means is that for you and signs the cookies cryptographically. What this means is that
the user could look at the contents of your cookie but not modify it, the user could look at the contents of your cookie but not modify it,
@ -752,12 +751,12 @@ sessions work::
# set the secret key. keep this really secret: # set the secret key. keep this really secret:
app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT' app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT'
The here mentioned :func:`~flask.escape` does escaping for you if you are The :func:`~flask.escape` mentioned here does escaping for you if you are
not using the template engine (like in this example). not using the template engine (as in this example).
.. admonition:: How to generate good secret keys .. admonition:: How to generate good secret keys
The problem with random is that it's hard to judge what random is. And The problem with random is that it's hard to judge what is truly random. And
a secret key should be as random as possible. Your operating system a secret key should be as random as possible. Your operating system
has ways to generate pretty random stuff based on a cryptographic has ways to generate pretty random stuff based on a cryptographic
random generator which can be used to get such a key: random generator which can be used to get such a key:
@ -775,9 +774,9 @@ Good applications and user interfaces are all about feedback. If the user
does not get enough feedback they will probably end up hating the does not get enough feedback they will probably end up hating the
application. Flask provides a really simple way to give feedback to a application. Flask provides a really simple way to give feedback to a
user with the flashing system. The flashing system basically makes it user with the flashing system. The flashing system basically makes it
possible to record a message at the end of a request and access it next possible to record a message at the end of a request and access it on the next
request and only next request. This is usually combined with a layout (and only the next) request. This is usually combined with a layout
template that does this. template to expose the message.
To flash a message use the :func:`~flask.flash` method, to get hold of the To flash a message use the :func:`~flask.flash` method, to get hold of the
messages you can use :func:`~flask.get_flashed_messages` which is also messages you can use :func:`~flask.get_flashed_messages` which is also
@ -790,10 +789,10 @@ Logging
.. versionadded:: 0.3 .. versionadded:: 0.3
Sometimes you might be in a situation where you deal with data that Sometimes you might be in a situation where you deal with data that
should be correct, but actually is not. For example you may have some client should be correct, but actually is not. For example you may have some client-side
side code that sends an HTTP request to the server but it's obviously code that sends an HTTP request to the server but it's obviously
malformed. This might be caused by a user tempering with the data, or the malformed. This might be caused by a user tampering with the data, or the
client code failing. Most of the time, it's okay to reply with ``400 Bad client code failing. Most of the time it's okay to reply with ``400 Bad
Request`` in that situation, but sometimes that won't do and the code has Request`` in that situation, but sometimes that won't do and the code has
to continue working. to continue working.

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