path: root/docs/narr/project.rst

.. _project_narr:

Creating a :mod:`repoze.bfg` Project
====================================

While it's possible to create a :mod:`repoze.bfg` application
completely manually, it's usfeul to be able to create a "skeleton"
:mod:`repoze.bfg` application using an application skeleton generator.
"Skeleton" projects can be created using the ``paster create`` command
in conjunction with :term:`Paste` templates.  Various project
templates that come with :mod:`repoze.bfg` make different
configuration assumptions about what type of application you're trying
to construct.

All existing project templates make the assumption that you want your
code to live in a Python :term:`package`.  Even if your application is
extremely simple, it is useful to place code that drives the
application within a package, because a package is more easily
extended with new code and an application that lives inside a package
can be distributed more easily than one which does not live within a
package.

.. index::
   pair: project; creating

.. _creating_a_project:

Creating the Project
--------------------

To start a :mod:`repoze.bfg` :term:`project`, use the ``paster
create`` facility using the interpreter from the virtualenv
(``bfgenv``) directory you created in :ref:`installing_chapter`.

.. code-block:: text

   $ bin/paster create -t bfg_starter

``paster create`` will ask you a single question: the *name* of the
project.  You should use a string without spaces and with only letters
in it.  Here's sample output from a run of ``paster create`` for a
project we name ``MyProject``:

.. code-block:: text

   $ bin/paster create -t bfg_starter
   Selected and implied templates:
     repoze.bfg#bfg  repoze.bfg starter project

   Enter project name: MyProject
   Variables:
     egg:      MyProject
     package:  myproject
     project:  MyProject
   Creating template bfg
   Creating directory ./MyProject
     Recursing into +package+
       Creating ./MyProject/myproject/
       Copying __init__.py to ./MyProject/myproject/__init__.py
       Copying configure.zcml to ./MyProject/myproject/configure.zcml
       Copying models.py to ./MyProject/myproject/models.py
       Copying run.py_tmpl to ./MyProject/myproject/run.py
       Recursing into templates
         Creating ./MyProject/myproject/templates/
         Copying mytemplate.pt to ./MyProject/myproject/templates/mytemplate.pt
         Recursing into static
           Creating ./MyProject/myproject/templates/static/
           Copying default.css to ./MyProject/myproject/templates/static/default.css
           Recursing into images
             Creating ./MyProject/myproject/templates/static/images/
             Copying img01.gif to ./MyProject/myproject/templates/static/images/img01.gif
             Copying img02.gif to ./MyProject/myproject/templates/static/images/img02.gif
             Copying img03.gif to ./MyProject/myproject/templates/static/images/img03.gif
             Copying img04.gif to ./MyProject/myproject/templates/static/images/img04.gif
             Copying spacer.gif to ./MyProject/myproject/templates/static/images/spacer.gif
           Copying templatelicense.txt to ./MyProject/myproject/templates/static/templatelicense.txt
       Copying tests.py_tmpl to ./MyProject/myproject/tests.py
       Copying views.py_tmpl to ./MyProject/myproject/views.py
     Copying +project+.ini_tmpl to ./MyProject/MyProject.ini
     Copying CHANGES.txt_tmpl to ./MyProject/CHANGES.txt
     Copying README.txt_tmpl to ./MyProject/README.txt
     Copying setup.py_tmpl to ./MyProject/setup.py
   Running /Users/chrism/projects/repoze/bfg/bin/python setup.py egg_info

As a result of invoking ``paster create``, a project is created in a
directory named ``MyProject``.  That directory is a :term:`setuptools`
:term:`project` directory from which a Python setuptools
:term:`distribution` can be created.  The ``setup.py`` file in that
directory can be used to distribute your application, or install your
application for deployment or development. A sample
:term:`PasteDeploy` ``.ini`` file named ``MyProject.ini`` will also be
created in the project directory.  You will use the ``paster serve``
command against this ``.ini`` file to run your application.

The ``MyProject`` project directory contains an additional
subdirectory named ``myproject`` (note the case difference)
representing a Python :term:`package` which holds very simple
:mod:`repoze.bfg` sample code.  This is where you'll edit your
application's Python code and templates.

.. note:: You can skip the interrogative question about a project
   name during ``paster create`` by adding the project name to the
   command line, e.g. ``paster create -t bfg_starter MyProject``.

.. index::
   single: paster templates
   single: project templates

.. _additional_paster_templates:

Additional Paster Templates
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Convenience :term:`Paste` templates for projects which will depend on
:term:`ZODB` or `SQLAlchemy <http://www.sqlalchemy.org/>`_ also exist.

- Use ``paster create -t bfg_zodb`` to create a project that depends on
  ZODB.

- Use ``paster create -t bfg_routesalchemy`` to create a project that
  depends on SQLAlchemy and :term:`URL dispatch` (no :term:`traversal`).

- Use ``paster create -t bfg_alchemy`` to create a project that
  depends on SQLAlchemy but *not* :term:`URL dispatch` (uses only
  :term:`traversal`).

Installing your Newly Created Project for Development
-----------------------------------------------------

Using the interpreter from the :term:`virtualenv` you create during
:ref:`installing_chapter`, invoke the following command when inside
the project directory.  The file named ``setup.py`` will be in the
root of the paster-generated project directory.  The ``python`` you're
invoking should be the one from your virtualenv.

.. code-block:: text

   $ ../bin/python setup.py develop

Elided output from a run of this command is shown below:

.. code-block:: text

   $ ../bin/python setup.py develop
   ...
   Finished processing dependencies for MyProject==0.1

This will install your application's :term:`package` into the
interpreter so it can be found and run as a :term:`WSGI` application
inside a WSGI server.

.. index::
   pair: running; tests

Running The Tests For Your Application
--------------------------------------

To run unit tests for your application, you should invoke them like
so:

.. code-block:: text

   $ ../bin/python setup.py test -q

Here's sample output from a test run:

.. code-block:: text

   $ python setup.py test -q
   running test
   running egg_info
   writing requirements to MyProject.egg-info/requires.txt
   writing MyProject.egg-info/PKG-INFO
   writing top-level names to MyProject.egg-info/top_level.txt
   writing dependency_links to MyProject.egg-info/dependency_links.txt
   writing entry points to MyProject.egg-info/entry_points.txt
   reading manifest file 'MyProject.egg-info/SOURCES.txt'
   writing manifest file 'MyProject.egg-info/SOURCES.txt'
   running build_ext
   ..
   ----------------------------------------------------------------------
   Ran 1 test in 0.108s

   OK

The tests are found in the ``tests.py`` module in your ``paster
create`` -generated project.  One sample test exists.

.. index::
   single: interactive shell

The Interactive Shell
---------------------

Once you've installed your program for development using ``setup.py
develop``, you can use an interactive shell to examine your
:mod:`repoze.bfg` application :term:`model` objects from a Python
prompt.  To do so, use the ``paster`` shell command with the
``bfgshell`` argument:

The first argument to ``bfgshell`` is the path to your application's
``.ini`` file.  The second is the section name inside the ``.ini``
file which points to your *application* as opposed to any other
section within the ``.ini`` file.  For example, if your application
``.ini`` file might have a ``[app:main]`` section that looks like so:

.. code-block:: ini
   :linenos:

   [app:main]
   use = egg:MyProject#app
   reload_templates = true
   debug_authorization = false
   debug_notfound = false

If so, you can use the following command to invoke a debug shell using
the name ``main`` as a section name:

.. code-block::  text

   [chrism@vitaminf bfgshellenv]$ ../bin/paster --plugin=repoze.bfg bfgshell \
         MyProject.ini main
   Python 2.4.5 (#1, Aug 29 2008, 12:27:37) 
   [GCC 4.0.1 (Apple Inc. build 5465)] on darwin
   Type "help" for more information. "root" is the BFG app root object.
   >>> root
   <foo.models.MyModel object at 0x445270>

.. note:: You *might* get away without passing
          ``--plugin=repoze.bfg`` to the bfgshell command.

If you have `IPython <http://en.wikipedia.org/wiki/IPython>`_
installed in the interpreter you use to invoke the ``paster`` command,
the ``bfgshell`` command will use an IPython interactive shell instead
of a standard Python interpreter shell.  If you don't want this to
happen, even if you have IPython installed, you can pass the
``--disable-ipython`` flag to the ``bfgshell`` command to use a
standard Python interpreter shell unconditionally.

.. code-block::  text

   [chrism@vitaminf bfgshellenv]$ ../bin/paster --plugin=repoze.bfg bfgshell \
         MyProject.ini main

Press "Ctrl-D" to exit the interactive shell.

You should always use a section name argument that refers to the
actual ``app`` section within the Paste configuration file that points
at your :mod:`repoze.bfg` application *without any middleware
wrapping*.  In particular, a section name is inappropriate as the
second argument to "bfgshell" if the configuration section it names is
a ``pipeline`` rather than an ``app``.  For example, if you have the
following ``.ini`` file content:

.. code-block:: ini
   :linenos:

   [app:myapp]
   use = egg:MyProject#app
   reload_templates = true
   debug_authorization = false
   debug_notfound = false

   [pipeline:main]
   pipeline = egg:repoze.tm2#tm
              myapp

The command you use to invoke the interactive shell should be:

.. code-block::  text

   [chrism@vitaminf bfgshellenv]$ ../bin/paster --plugin=repoze.bfg bfgshell \
         MyProject.ini myapp

If you use ``main`` as the section name argument instead of ``myapp``
against the above ``.ini`` file, an error will likely occur.  Use the
most specific reference to the application within the ``.ini`` file
possible as the section name argument.

Runnning The Project Application
--------------------------------

Once the project is installed for development, you can run the
application it represents using the ``paster serve`` command against
the generated ``MyProject.ini`` configuration file:

.. sidebar:: Using ``mod_wsgi``

   You can also use :term:`mod_wsgi` to serve your :mod:`repoze.bfg`
   application using the Apache web server rather than the
   "pure-Python" server that is started as a result of ``paster
   serve``.  See :ref:`modwsgi_tutorial` for details.  However, it is
   usually easier to develop an application using the ``paster serve``
   webserver, as exception and debugging output will be sent to the
   console.

.. code-block:: text

   $ ../bin/paster serve MyProject.ini

Here's sample output from a run:

.. code-block:: text

   $ paster serve MyProject.ini
   Starting server in PID 16601.
   serving on 0.0.0.0:6543 view at http://127.0.0.1:6543

By default, generated :mod:`repoze.bfg` applications will listen on
port 6543.

.. note:: During development, it's often useful to run ``paster
   serve`` using its ``--reload`` option.  When any Python module your
   project uses, changes, it will restart the server, which makes
   development easier, as changes to Python code under
   :mod:`repoze.bfg` is not put into effect until the server restarts.

Viewing the Application
-----------------------

Visit ``http://localhost:6543/`` in your browser.  You will see
something in your browser like what is displayed below:

.. image:: project.png

That's the page shown by default when you visit an unmodified ``paster
create``-generated application.

.. index::
   single: project structure

The Project Structure
---------------------

Our generated :mod:`repoze.bfg` application is a setuptools
:term:`project` (named ``MyProject``), which contains a Python
:term:`package` (which is *also* named ``myproject``, but lowercased;
the paster template generates a project which contains a package that
shares its name except for case).

The ``MyProject`` project has the following directory structure::

  MyProject/
  |-- CHANGES.txt
  |-- README.txt
  |-- myproject
  |   |-- __init__.py
  |   |-- configure.zcml
  |   |-- models.py
  |   |-- run.py
  |   |-- templates
  |   |   |-- mytemplate.pt
  |   |   `-- static/
  |   |-- tests.py
  |   `-- views.py
  |-- MyProject.ini
  `-- setup.py

The ``MyProject`` :term:`Project`
---------------------------------

The ``MyProject`` :term:`project` is the distribution and deployment
wrapper for your application.  It contains both the ``myproject``
:term:`package` representing your application as well as files used to
describe, run, and test your application.

#. ``CHANGES.txt`` describes the changes you've made to the
   application.  It is conventionally written in
   :term:`ReStructuredText` format.

#. ``README.txt`` describes the application in general.  It is
   conventionally written in :term:`ReStructuredText` format.

#. ``MyProject.ini`` is a :term:`PasteDeploy` configuration file that
   can be used to execute your application.

#. ``setup.py`` is the file you'll use to test and distribute your
   application.  It is a standard :term:`setuptools` ``setup.py``
   file.

We won't describe the ``CHANGES.txt`` or ``README.txt`` files.

.. index::
   single: PasteDeploy
   single: ini file

.. _MyProject_ini:

``MyProject.ini``
~~~~~~~~~~~~~~~~~

The ``MyProject.ini`` file is a :term:`PasteDeploy` configuration
file.  Its purpose is to specify an application to run when you invoke
``paster serve`` when you start an application, as well as the
deployment settings provided to that application.

The generated ``MyProject.ini`` file looks like so:

.. literalinclude:: MyProject/MyProject.ini
   :linenos:

This file contains several "sections" including ``[DEFAULT]``,
``[app:main]``, and ``[server:main]``.

The ``[DEFAULT]`` section consists of global parameters that are
shared by all the applications, servers and :term:`middleware` defined
within the configuration file.  By default it contains one key
``debug``, which is set to ``true``.  This key is used by various
components to decide whether to act in a "debugging" mode.
``repoze.bfg`` itself does not do anything at all with this parameter,
and neither does any generated sample application.

The ``[app:main]`` section represents configuration for your
application.  This section name represents the ``main`` application
(and it's an ``app`` -lication, thus ``app:main``), signifying that
this is the default application run by ``paster serve`` when it is
invoked against this configuration file.  The name ``main`` is a
convention signifying that it the default application.

The ``use`` setting is required in the ``[app:main]`` section.  The
``use`` setting points at a :term:`setuptools` :term:`entry point`
named ``MyProject#app`` (the ``egg:`` prefix in ``egg:MyProject#app``
indicates that this is an entry point *URI* specifier, where the
"scheme" is "egg"; there are no other schemes currently, so the
``egg:`` prefix is arguably not very useful).

.. note::

   This part of configuration can be confusing so let's try to clear
   things up a bit.  Take a look at the generated ``setup.py`` file
   for this project.  Note that the ``entry_point`` line in
   ``setup.py`` points at a string which looks a lot like an ``.ini``
   file.  This string representation of an ``.ini`` file has a section
   named ``[paste.app_factory]``.  Within this section, there is a key
   named ``app`` (the entry point name) which has a value
   ``myproject.run:app``.  The *key* ``app`` is what our
   ``egg:MyProject#app`` value of the ``use`` section in our config
   file is pointing at.  The value represents a Python "dotted-name"
   path, which refers to a callable in our ``myproject`` package's
   ``run.py`` module.

   In English, this entry point can thus be referred to as a "Paste
   application factory in the ``MyProject`` project which has the
   entry point named ``app`` where the entry point refers to a ``app``
   function in the ``mypackage.run`` module".  If indeed if you open
   up the ``run.py`` module generated within the ``myproject``
   package, you'll see a ``app`` function.  This is the function
   called :term:`PasteDeploy` when the ``paster serve`` command is
   invoked against our application.  It accepts a global configuration
   object and *returns* an instance of our application.

The ``use`` setting is the only setting required in the ``[app:main]``
section unless you've changed the callable referred to by the
``MyProject#app`` entry point to accept more arguments: other settings
you add to this section are passed as keywords arguments to the
callable represented by this entry point (``app`` in our ``run.py``
module).  You can provide startup-time configuration parameters to
your application by requiring more settings in this section.

The ``reload_templates`` setting in the ``[app:main]`` section is a
:mod:`repoze.bfg`-specific setting which is passed into the framework.
If it exists, and is ``true``, :term:`Chameleon` template changes will
not require an application restart to be detected.  See
:ref:`reload_templates_section` for more information.

.. warning:: The ``reload_templates`` option should be turned off for
   production applications, as template rendering is slowed when it is
   turned on.

Various other settings may exist in this section having to do with
debugging or influencing runtime behavior of a :mod:`repoze.bfg`
application.  See :ref:`environment_chapter` for more information
about these settings.

The ``[server:main]`` section of the configuration file configures a
WSGI server which listens on port 6543.  It is configured to listen on
all interfaces (``0.0.0.0``).  The ``Paste#http`` server will create a
new thread for each request.

.. note::

  In general, :mod:`repoze.bfg` applications should be
  threading-aware.  It is not required that a :mod:`repoze.bfg`
  application be nonblocking as all application code will run in its
  own thread, provided by the server you're using.

See the :term:`PasteDeploy` documentation for more information about
other types of things you can put into this ``.ini`` file, such as
other applications, :term:`middleware` and alternate servers.

.. index::
   single: setup.py

``setup.py``
~~~~~~~~~~~~

The ``setup.py`` file is a :term:`setuptools` setup file.  It is meant
to be run directly from the command line to perform a variety of
functions, such as testing your application, packaging, and
distributing your application.

.. note::

  ``setup.py`` is the defacto standard which Python developers use to
  distribute their reusable code.  You can read more about
  ``setup.py`` files and their usage in the :term:`Setuptools`
  documentation.

Our generated ``setup.py`` looks like this:

.. literalinclude:: MyProject/setup.py
   :linenos:

The ``setup.py`` file calls the setuptools ``setup`` function, which
does various things depending on the arguments passed to ``setup.py``
on the command line.

Within the arguments to this function call, information about your
application is kept.  While it's beyond the scope of this
documentation to explain everything about setuptools setup files, we'll
provide a whirlwind tour of what exists in this file here.

Your application's name (this can be any string) is specified in the
``name`` field.  The version number is specified in the ``version``
value.  A short description is provided in the ``description`` field.
The ``long_description`` is conventionally the content of the README
and CHANGES file appended together.  The ``classifiers`` field is a
list of `Trove
<http://pypi.python.org/pypi?%3Aaction=list_classifiers>`_ classifiers
describing your application.  ``author`` and ``author_email`` are text
fields which probably don't need any description.  ``url`` is a field
that should point at your application project's URL (if any).
``packages=find_packages()`` causes all packages within the project to
be found when packaging the application.  ``include_package_data``
will include non-Python files when the application is packaged if
those files are checked into version control.  ``zip_safe`` indicates
that this package is not safe to ship as a zipped egg (it will unpack
as a directory, which is more convenient).  ``install_requires`` and
``tests_require`` indicate that this package depends on the
``repoze.bfg`` package.  ``test_suite`` points at the package for our
application, which means all tests found in the package will be
installed.  We examined ``entry_points`` in our discussion of the
``MyProject.ini`` file; this file defines the ``app`` entry point that
represents our project's application.

Usually you only need to think about the contents of the ``setup.py``
file when distributing your application to other people, or when
versioning your application for your own use.  For fun, you can try
this command now::

  python setup.py sdist

This will create a tarball of your application in a ``dist``
subdirectory named ``MyProject-0.1.tar.gz``.  You can send this
tarball to other people who want to use your application.

.. warning::

   By default, ``setup.py sdist`` does not place non-Python-source
   files in generated tarballs.  This means, in this case, that the
   ``templates/mytemplate.pt`` file and the files in the
   ``templates/static`` directory are not packaged in the tarball.  To
   allow this to happen, check all the files that you'd like to be
   distributed along with your application's Python files into a
   version control system such as Subversion.  After you do this, when
   you rerun ``setup.py sdist``, all files checked into the version
   control system will be included in the tarball.

.. index::
   single: package

The ``myproject`` :term:`Package`
---------------------------------

The ``myproject`` :term:`package` lives inside the ``MyProject``
:term:`project`.  It contains:

#. An ``__init__.py`` file which signifies that this is a Python
   :term:`package`.  It is conventionally empty, save for a single
   comment at the top.

#. A ``configure.zcml`` is a :term:`ZCML` file which maps view names
   to model types.  Its contents populate the :term:`application
   registry` when loaded.

#. A ``models.py`` module, which contains :term:`model` code.

#. A ``run.py`` module, which contains code that helps users run the
   application.

#. A ``templates`` directory, which contains :term:`Chameleon` (or
   other types of) templates.

#. A ``tests.py`` module, which contains unit test code for the
   application.

#. A ``views.py`` module, which contains view code for the
   application.

These are purely conventions established by the ``paster`` template:
:mod:`repoze.bfg` doesn't insist that you name things in any
particular way.

.. index::
   single: configure.zcml

``configure.zcml``
~~~~~~~~~~~~~~~~~~

The ``configure.zcml`` contains configuration statements that inform
the :term:`application registry`. It looks like so:

.. literalinclude:: MyProject/myproject/configure.zcml
   :linenos:
   :language: xml

#. Line 1 provides the root node and namespaces for the configuration
   language.  ``http://namespaces.repoze.org/bfg`` is the default XML
   namespace.  Add-on packages may require other namespaces.

#. Line 4 initializes :mod:`repoze.bfg`-specific configuration
   directives by including the :mod:`repoze.bfg.includes` package.
   This causes all of the ZCML within the ``configure.zcml`` of the
   :mod:`repoze.bfg.includes` package (which can be found in the main
   :mod:`repoze.bfg` sources) to be "included" in this configuration
   file's scope.  Effectively this means that we can use (for this
   example) the ``view`` and ``static`` directives which follow later
   in this file.

#. Lines 6-10 register a "default view" (a view that has no ``name``
   attribute).  It is ``for`` model objects that are instances of the
   :class:`myproject.models.MyModel` class.  The ``view`` attribute
   points at a Python function that does all the work for this view.
   Note that the values of both the ``for`` attribute and the ``view``
   attribute begin with a single period.  Names that begin with a
   period are "shortcuts" which point at files relative to the
   :term:`package` in which the ``configure.zcml`` file lives.  In
   this case, since the ``configure.zcml`` file lives within the
   :mod:`myproject` package, the shortcut ``.models.MyModel`` could
   also be spelled ``myproject.models.MyModel`` (forming a full Python
   dotted-path name to the ``MyModel`` class).  Likewise the shortcut
   ``.views.my_view`` could be replaced with
   ``myproject.views.my_view``.

   The view declaration also names a ``renderer``, which in this case
   is a template that will be used to render the result of the view
   callable.  This particular view declaration points at
   ``templates/mytemplate.pt``, which is a *relative* file
   specification (it's relative to the directory in which the
   ``configure.zcml`` file lives).  The template file it points at is
   a :term:`Chameleon` ZPT template file.

#. Lines 12-15 register a static view, which will register a view
   which serves up the files from the ``templates/static`` directory
   relative to the directory in which the ``configure.zcml`` file
   lives.

#. Line 17 ends the ``configure`` root tag.

.. index::
   single: views.py

``views.py``
~~~~~~~~~~~~

Much of the heavy lifting in a :mod:`repoze.bfg` application comes in
the form of *views*.  A :term:`view` is the bridge between the content
in the model, and the response given back to a browser.

.. literalinclude:: MyProject/myproject/views.py
   :linenos:

Lines 1-2 provide the ``my_view`` that was registered as the view.
``configure.zcml`` said that the default URL for instances that are of
the class :class:`myproject.models.MyModel` should run this
:func:`myproject.views.my_view` function.

The function is handed two pieces of information: the :term:`context`
and the :term:`request`.  The *context* is the term :term:`model`
found via :term:`traversal` (or via :term:`URL dispatch`).  The
*request* is an instance of the :term:`WebOb` ``Request`` class
representing the browser's request to our server.

This view returns a dictionary.  When this view is invoked, a
:term:`renderer` renders the dictionary returned by the view, and
returns the result as the :term:`response`.  This view is configured
to invoke a renderer which uses a :term:`Chameleon` ZPT template
(``templates/my_template.pt``, as specified in the ``configure.zcml``
file).

See :ref:`views_which_use_a_renderer` for more information about how
views, renderers, and templates relate and cooperate.

.. note:: because our ``MyProject.ini`` has a ``reload_templates =
   true`` directive indicating that templates should be reloaded when
   they change, you won't need to restart the application server to
   see changes you make to templates.  During development, this is
   handy.  If this directive had been ``false`` (or if the directive
   did not exist), you would need to restart the application server
   for each template change.  For production applications, you should
   set your project's ``reload_templates`` to ``false`` to increase
   the speed at which templates may be rendered.

.. index::
   single: models.py

.. _modelspy_project_section:

``models.py``
~~~~~~~~~~~~~

The ``models.py`` module provides the :term:`model` data for our
application.  We write a class named ``MyModel`` that provides the
behavior.  

.. literalinclude:: MyProject/myproject/models.py
   :linenos:

#. Lines 1-2 define the MyModel class.

#. Line 4 defines an instance of MyModel as the root.

#. Line 6 is a "root factory" function that will be called by the
   :mod:`repoze.bfg` *Router* for each request when it wants to find
   the root of the object graph.  Conventionally this is called
   ``get_root``.

In a "real" application, the root object would not be such a simple
object.  Instead, it would be an object that could access some
persistent data store, such as a database.  :mod:`repoze.bfg` doesn't
make any assumption about which sort of datastore you'll want to use,
so the sample application uses an instance of
:class:`myproject.models.MyModel` to represent the root.

.. index::
   single: run.py

``run.py``
~~~~~~~~~~

We need a small Python module that configures our application and
advertises itself to our :term:`PasteDeploy` ``.ini`` file.  For
convenience, we also make it possible to run this module directory
without the PasteDeploy configuration file:

.. literalinclude:: MyProject/myproject/run.py
   :linenos:

#. Line 1 imports the :term:`Configurator` class from
   :mod:`repoze.bfg.configuration` that we use later.

#. Line 2 imports the ``get_root`` function from
   :mod:`myproject.models` that we use later.

#. Lines 4-13 define a function that returns a :mod:`repoze.bfg`
   WSGI application.  This function is meant to be called
   by the :term:`PasteDeploy` framework as a result of running
   ``paster serve``.

``templates/mytemplate.pt``
~~~~~~~~~~~~~~~~~~~~~~~~~~~

The single :term:`Chameleon` template in the project looks like so:

.. literalinclude:: MyProject/myproject/templates/mytemplate.pt
   :linenos:
   :language: xml

It displays a default page when rendered.  It is referenced by the
``view`` declaration's ``renderer`` attribute in the
``configure.zcml`` file.  Templates are accessed and used by view
declarations and sometimes by view functions themselves.  See
:ref:`views_which_use_a_renderer` for more information about
renderers.

``templates/static``
~~~~~~~~~~~~~~~~~~~~

This directory contains static resources which support the
``mytemplate.pt`` template.  It includes CSS and images.

.. index::
   single: tests.py

``tests.py``
~~~~~~~~~~~~

The ``tests.py`` module includes unit tests for your application.

.. literalinclude:: MyProject/myproject/tests.py
   :linenos:

This sample ``tests.py`` file has a single unit test defined within
it.  This test is executed when you run ``python setup.py test -q``.
You may add more tests here as you build your application.  You are
not required to write tests to use :mod:`repoze.bfg`, this file is
simply provided as convenience and example.

See :ref:`unittesting_chapter` for more information about writing
:mod:`repoze.bfg` unit tests.