|
|
|
|
Foreword
|
|
|
|
|
========
|
|
|
|
|
|
|
|
|
|
Read this before you get started with Flask. This hopefully answers some
|
|
|
|
|
questions about the purpose and goals of the project, and when you
|
|
|
|
|
should or should not be using it.
|
|
|
|
|
|
|
|
|
|
What does "micro" mean?
|
|
|
|
|
-----------------------
|
|
|
|
|
|
|
|
|
|
“Micro” does not mean that your whole web application has to fit into a single
|
|
|
|
|
Python file, although it certainly can. Nor does it mean that Flask is lacking
|
|
|
|
|
in functionality. The "micro" in microframework means Flask aims to keep the
|
|
|
|
|
core simple but extensible. Flask won't make many decisions for you, such as
|
|
|
|
|
what database to use. Those decisions that it does make, such as what
|
|
|
|
|
templating engine to use, are easy to change. Everything else is up to you, so
|
|
|
|
|
that Flask can be everything you need and nothing you don't.
|
|
|
|
|
|
|
|
|
|
By default, Flask does not include a database abstraction layer, form
|
|
|
|
|
validation or anything else where different libraries already exist that can
|
|
|
|
|
handle that. Instead, Flask supports extensions to add such functionality to
|
|
|
|
|
your application as if it was implemented in Flask itself. Numerous extensions
|
|
|
|
|
provide database integration, form validation, upload handling, various open
|
|
|
|
|
authentication technologies, and more. Flask may be "micro", but it's ready for
|
|
|
|
|
production use on a variety of needs.
|
|
|
|
|
|
|
|
|
|
Configuration and Conventions
|
|
|
|
|
-----------------------------
|
|
|
|
|
|
|
|
|
|
Flask has many configuration values, with sensible defaults, and a few
|
|
|
|
|
conventions when getting started. By convention templates and static files are
|
|
|
|
|
stored in subdirectories within the application's Python source tree, with the
|
|
|
|
|
names :file:`templates` and :file:`static` respectively. While this can be changed you
|
|
|
|
|
usually don't have to, especially when getting started.
|
|
|
|
|
|
|
|
|
|
Growing with Flask
|
|
|
|
|
------------------
|
|
|
|
|
|
|
|
|
|
Once you have Flask up and running, you'll find a variety of extensions
|
|
|
|
|
available in the community to integrate your project for production. The Flask
|
|
|
|
|
core team reviews extensions and ensures approved extensions do not break with
|
|
|
|
|
future releases.
|
|
|
|
|
|
|
|
|
|
As your codebase grows, you are free to make the design decisions appropriate
|
|
|
|
|
for your project. Flask will continue to provide a very simple glue layer to
|
|
|
|
|
the best that Python has to offer. You can implement advanced patterns in
|
|
|
|
|
SQLAlchemy or another database tool, introduce non-relational data persistence
|
|
|
|
|
as appropriate, and take advantage of framework-agnostic tools built for WSGI,
|
|
|
|
|
the Python web interface.
|
|
|
|
|
|
|
|
|
|
Flask includes many hooks to customize its behavior. Should you need more
|
|
|
|
|
customization, the Flask class is built for subclassing. If you are interested
|
|
|
|
|
in that, check out the :ref:`becomingbig` chapter. If you are curious about
|
|
|
|
|
the Flask design principles, head over to the section about :ref:`design`.
|
|
|
|
|
|
|
|
|
|
Continue to :ref:`installation`, the :ref:`quickstart`, or the
|
|
|
|
|
:ref:`advanced_foreword`.
|
