.. _getting_started: =============== Getting Started =============== This section is intended to get Pylons up and running as fast as possible and provide a quick overview of the project. Links are provided throughout to encourage exploration of the various aspects of Pylons. ************ Requirements ************ * Python 2 series above and including 2.4 (Python 3 or later not supported at this time) .. _installing_pylons: ********** Installing ********** To avoid conflicts with system-installed Python libraries, Pylons comes with a boot-strap Python script that sets up a "virtual" Python environment. Pylons will then be installed under the virtual environment. .. admonition:: By the Way :term:`virtualenv` is a useful tool to create isolated Python environments. In addition to isolating packages from possible system conflicts, it makes it easy to install Python libraries using :term:`easy_install` without dumping lots of packages into the system-wide Python. The other great benefit is that no root access is required since all modules are kept under the desired directory. This makes it easy to setup a working Pylons install on shared hosting providers and other systems where system-wide access is unavailable. 1. Download the `go-pylons.py `_ script. 2. Run the script and specify a directory for the virtual environment to be created under: .. code-block:: bash $ python go-pylons.py mydevenv .. admonition:: Tip The two steps can be combined on unix systems with curl using the following short-cut: .. code-block:: bash $ curl http://pylonshq.com/download/1.0/go-pylons.py | python - mydevenv To isolate further from additional system-wide Python libraries, run with the --no-site-packages option: .. code-block:: bash $ python go-pylons.py --no-site-packages mydevenv | **How it Works** The ``go-pylons.py`` script is little more than a basic :term:`virtualenv` bootstrap script, that then does ``easy_install Pylons==1.0``. You could do the equivilant steps by manually fetching the ``virtualenv.py`` script and then installing Pylons like so: .. code-block:: bash curl -O http://bitbucket.org/ianb/virtualenv/raw/8dd7663d9811/virtualenv.py python virtualenv.py mydevenv mydevenv/bin/easy_install Pylons==1.0 This will leave a functional virtualenv and Pylons installation. Activate the virtual environment (scripts may also be run by specifying the full path to the mydevenv/bin dir): .. code-block:: bash $ source mydevenv/bin/activate Or on Window to activate: .. code-block:: text > mydevenv\Scripts\activate.bat .. note:: If you get an error such as:: ImportError: No module named _md5 during the install. It is likely that your Python installation is missing standard libraries needed to run Pylons. Debian and other systems using debian packages most frequently encounter this, make sure to install the ``python-dev`` packages and ``python-hashlib`` packages. Working Directly From the Source Code ===================================== `Mercurial `_ must be installed to retrieve the latest development source for Pylons. `Mercurial packages `_ are also available for Windows, MacOSX, and other OS's. Check out the latest code: .. code-block:: bash $ hg clone http://bitbucket.org/bbangert/pylons/ To tell setuptools to use the version in the ``Pylons`` directory: .. code-block:: bash $ cd pylons $ python setup.py develop The active version of Pylons is now the copy in this directory, and changes made there will be reflected for Pylons apps running. ************************* Creating a Pylons Project ************************* Create a new project named ``helloworld`` with the following command: .. code-block:: bash $ paster create -t pylons helloworld .. note:: Windows users must configure their ``PATH`` as described in :ref:`windows_notes`, otherwise they must specify the full path to the ``paster`` command (including the virtual environment bin directory). Running this will prompt for two choices: 1. which templating engine to use 2. whether to include :term:`SQLAlchemy` support Hit enter at each prompt to accept the defaults (Mako templating, no :term:`SQLAlchemy`). Here is the created directory structure with links to more information: - helloworld - MANIFEST.in - README.txt - development.ini - :ref:`run-config` - docs - ez_setup.py - helloworld (See the nested :ref:`helloworld directory `) - helloworld.egg-info - setup.cfg - setup.py - :ref:`setup-config` - test.ini .. _helloworld_dir: The nested ``helloworld directory`` looks like this: - helloworld - __init__.py - config - environment.py - :ref:`environment-config` - middleware.py - :ref:`middleware-config` - routing.py - :ref:`url-config` - controllers - :ref:`controllers` - lib - app_globals.py - :term:`app_globals` - base.py - helpers.py - :ref:`helpers` - model - :ref:`models` - public - templates - :ref:`templates` - tests - :ref:`testing` - websetup.py - :ref:`run-config` *********************** Running the application *********************** Run the web application: .. code-block:: bash $ cd helloworld $ paster serve --reload development.ini The command loads the project's server configuration file in :file:`development.ini` and serves the Pylons application. .. note:: The ``--reload`` option ensures that the server is automatically reloaded if changes are made to Python files or the :file:`development.ini` config file. This is very useful during development. To stop the server press :command:`Ctrl+c` or the platform's equivalent. The paster serve command can be run anywhere, as long as the development.ini path is properly specified. Generally during development it's run in the root directory of the project. Visiting http://127.0.0.1:5000/ when the server is running will show the welcome page. *********** Hello World *********** To create the basic hello world application, first create a :term:`controller` in the project to handle requests: .. code-block:: bash $ paster controller hello Open the :file:`helloworld/controllers/hello.py` module that was created. The default controller will return just the string 'Hello World': .. code-block:: python import logging from pylons import request, response, session, tmpl_context as c, url from pylons.controllers.util import abort, redirect from helloworld.lib.base import BaseController, render log = logging.getLogger(__name__) class HelloController(BaseController): def index(self): # Return a rendered template #return render('/hello.mako') # or, Return a response return 'Hello World' At the top of the module, some commonly used objects are imported automatically. Navigate to http://127.0.0.1:5000/hello/index where there should be a short text string saying "Hello World" (start up the app if needed): .. image:: _static/helloworld.png .. admonition:: Tip :ref:`url-config` explains how URL's get mapped to controllers and their methods. Add a template to render some of the information that's in the :term:`environ`. First, create a :file:`hello.mako` file in the :file:`templates` directory with the following contents: .. code-block:: mako Hello World, the environ variable looks like:
${request.environ} The :term:`request` variable in templates is used to get information about the current request. :ref:`Template globals ` lists all the variables Pylons makes available for use in templates. Next, update the :file:`controllers/hello.py` module so that the index method is as follows: .. code-block:: python class HelloController(BaseController): def index(self): return render('/hello.mako') Refreshing the page in the browser will now look similar to this: .. image:: _static/hellotemplate.png