Project Layout
==============

Create a project directory and enter it:

.. code-block:: none

    $ mkdir flask-tutorial
    $ cd flask-tutorial

Then follow the :doc:`installation instructions </installation>` to set
up a Python virtual environment and install Flask for your project.

The tutorial will assume you're working from the ``flask-tutorial``
directory from now on. The file names at the top of each code block are
relative to this directory.

----

A Flask application can be as simple as a single file.

.. code-block:: python
    :caption: ``hello.py``

    from flask import Flask

    app = Flask(__name__)


    @app.route('/')
    def hello():
        return 'Hello, World!'

However, as a project gets bigger, it becomes overwhelming to keep all
the code in one file. Python projects use *packages* to organize code
into multiple modules that can be imported where needed, and the
tutorial will do this as well.

The project directory will contain:

* ``flaskr/``, a Python package containing your application code and
  files.
* ``tests/``, a directory containing test modules.
* ``venv/``, a Python virtual environment where Flask and other
  dependencies are installed.
* Installation files telling Python how to install your project.
* Version control config, such as `git`_. You should make a habit of
  using some type of version control for all your projects, no matter
  the size.
* Any other project files you might add in the future.

.. _git: https://git-scm.com/

By the end, your project layout will look like this:

.. code-block:: none

    /home/user/Projects/flask-tutorial
    ├── flaskr/
    │   ├── __init__.py
    │   ├── db.py
    │   ├── schema.sql
    │   ├── auth.py
    │   ├── blog.py
    │   ├── templates/
    │   │   ├── base.html
    │   │   ├── auth/
    │   │   │   ├── login.html
    │   │   │   └── register.html
    │   │   └── blog/
    │   │       ├── create.html
    │   │       ├── index.html
    │   │       └── update.html
    │   └── static/
    │       └── style.css
    ├── tests/
    │   ├── conftest.py
    │   ├── data.sql
    │   ├── test_factory.py
    │   ├── test_db.py
    │   ├── test_auth.py
    │   └── test_blog.py
    ├── venv/
    ├── setup.py
    └── MANIFEST.in

If you're using version control, the following files that are generated
while running your project should be ignored. There may be other files
based on the editor you use. In general, ignore files that you didn't
write. For example, with git:

.. code-block:: none
    :caption: ``.gitignore``

    venv/

    *.pyc
    __pycache__/

    instance/

    .pytest_cache/
    .coverage
    htmlcov/

    dist/
    build/
    *.egg-info/

Continue to :doc:`factory`.