:app:`Pyramid` ProjectCreating a
As we saw in :ref:`firstapp_chapter`, it's possible to create a :app:`Pyramid` application completely manually. However, it's usually more convenient to use our :term:`cookiecutter` to generate a basic :app:`Pyramid` :term:`project`.
A project is a directory that contains at least one Python :term:`package`. You'll use the :app:`Pyramid` cookiecutter to create a project, and you'll create your application logic within a package that lives inside the project. Even if your application is extremely simple, it is useful to place code that drives the application within a package, because (1) a package is more easily extended with new code, and (2) an application that lives inside a package can also be distributed more easily than one which does not live within a package.
The Pylons Project provides a :app:`Pyramid` cookiecutter that you can use to generate a project. Our cookiecutter allows several configuration options to generate the type of application you're trying to construct.
This cookiecutter is rendered using the
cookiecutter command that you may install.
.. seealso:: See also `Cookiecutter Installation <https://cookiecutter.readthedocs.io/en/latest/installation.html>`_.
.. index:: single: cookiecutters single: pyramid-cookiecutter-starter
The Pyramid cookiecutter released under the Pylons Project offers the following configuration options:
- templating libraries (:term:`Jinja2`, :term:`Chameleon`, or :term:`Mako`)
- the persistence mechanism (no persistence mechanism, :term:`SQLAlchemy` with SQLite, or :term:`ZODB`)
- the mechanism of mapping URLs to code (:term:`URL dispatch` or :term:`traversal`)
All configuration options offer a choice of templating language.
The configuration of mapping URLs to code (routing) depends on the backend option selected, with additional variations as follows.
- :term:`URL dispatch` for routing
- SQLite for persistent storage, :term:`SQLAlchemy` for an ORM, :term:`URL dispatch` for routing, and :term:`Alembic` for database migrations
- :term:`ZODB` for persistent storage and :term:`traversal` for routing
.. index:: single: creating a project single: project single: cookiecutter
Creating the Project
In :ref:`installing_chapter`, you created a virtual Python environment via the
venv command. We called the virtual environment directory
env and set an environment variable
VENV to its path.
We assume that you :ref:`previously installed cookiecutter <cookiecutters>`, following its installation instructions.
When we invoke
cookiecutter, it will create a directory that represents our project.
We assume our current working directory is the value of
On all platforms, generate a project using cookiecutter.
cookiecutter gh:Pylons/pyramid-cookiecutter-starter --checkout master
If prompted for the first item, accept the default
yes by hitting return.
You've cloned ~/.cookiecutters/pyramid-cookiecutter-starter before. Is it okay to delete and re-clone it? [yes]: yes project_name [Pyramid Scaffold]: myproject repo_name [myproject]: myproject Select template_language: 1 - jinja2 2 - chameleon 3 - mako Choose from 1, 2, 3 : 1 Select backend: 1 - none 2 - sqlalchemy 3 - zodb Choose from 1, 2, 3 : 1
We then run through the following commands.
# Reset our environment variable for a new virtual environment. export VENV=~/env/myproject/env # Change directory into your newly created project. cd myproject # Create a new virtual environment... python3 -m venv $VENV # ...where we upgrade packaging tools. env/bin/pip install --upgrade pip setuptools
Or on Windows:
# Reset our environment variable for a new virtual environment. set VENV=c:\env\myproject\env # Change directory into your newly created project. cd myproject # Create a new virtual environment... python -m venv %VENV% # ...where we upgrade packaging tools. %VENV%\Scripts\pip install --upgrade pip setuptools
As a result of invoking the
cookiecutter command, a directory named
myproject is created. That directory is a :term:`project` directory. The
setup.py file in that directory can be used to distribute your application,
or install your application for deployment or development.
.ini file named
development.ini will be created in the project
directory. You will use this
.ini file to configure a server, to run your
application, and to debug your application.
It contains configuration that enables an interactive debugger and :term:`settings` optimized for development.
.ini file named
production.ini will also be created in the
project directory. It contains configuration that disables any interactive
debugger (to prevent inappropriate access and disclosure), and turns off a
number of debugging settings. You can use this file to put your application
myproject project directory contains an additional subdirectory named
myproject representing a Python :term:`package`
which holds very simple :app:`Pyramid` sample code. This is where you'll edit
your application's Python code and templates.
We created this project in a directory next to its virtual environment directory.
However, note that this is not mandatory. The project directory can go more or
less anywhere on your filesystem. You don't need to put it in a special "web
server" directory. You could put it within a virtual environment
directory. The author uses Linux mainly, and tends to put project directories
which he creates within his
~/projects directory. On Windows, it's a good
idea to put project directories within a directory that contains no space
characters, so it's wise to avoid a path that contains, i.e.,
Documents. As a result, the author, when he uses Windows, just puts his
You'll need to avoid using
cookiecutter to create a project with the same
name as a Python standard library component. In particular, this means you
should avoid using the names
test, both of which conflict
with Python standard library packages. You should also avoid using the name
pyramid, which will conflict with Pyramid itself.
.. index:: single: setup.py develop single: development install
Installing your Newly Created Project for Development
To install a newly created project for development, you should
cd to the
newly created project directory and use the Python interpreter from the
:term:`virtual environment` you created during :ref:`installing_chapter` to
invoke the command
pip install -e ., which installs the project in
development mode (
-e is for "editable") into the current directory (
The file named
setup.py will be in the root of the cookiecutter-generated
project directory. The
python you're invoking should be the one that lives
Scripts on Windows) directory of your virtual Python
environment. Your terminal's current working directory must be the newly
created project directory.
$VENV/bin/pip install -e .
Or on Windows:
%VENV%\Scripts\pip install -e .
Elided output from a run of this command on Unix is shown below:
Running setup.py develop for myproject Successfully installed Jinja2-2.8 Mako-1.0.6 MarkupSafe-0.23 \ PasteDeploy-1.5.2 Pygments-2.1.3 WebOb-1.7.0 myproject pyramid-1.7.3 \ pyramid-debugtoolbar-3.0.5 pyramid-jinja2-2.7 pyramid-mako-1.0.2 \ repoze.lru-0.6 translationstring-1.3 venusian-1.0 waitress-1.0.1 \ zope.deprecation-4.2.0 zope.interface-4.3.3
This will install a :term:`distribution` representing your project into the
virtual environment interpreter's library set so it can be found by
statements and by other console scripts such as
.. index:: single: running tests single: tests (running)
Running the Tests for Your Application
To run unit tests for your application, you must first install the testing dependencies.
$VENV/bin/pip install -e ".[testing]"
%VENV%\Scripts\pip install -e ".[testing]"
Once the testing requirements are installed, then you can run the tests using
pytest command that was just installed in the
bin directory of
your virtual environment.
Here's sample output from a test run on Unix:
$VENV/bin/pytest -q .. 2 passed in 0.47 seconds
The tests themselves are found in the
tests.py module in your
cookiecutter-generated project. Within a project generated by the
pyramid-cookiecutter-starter cookiecutter, only two sample tests exist.
-q option is passed to the
pytest command to limit the output
to a stream of dots. If you don't pass
-q, you'll see verbose test
result output (which normally isn't very useful).
Alternatively, if you'd like to see test coverage, pass the
$VENV/bin/pytest --cov -q
Cookiecutters include configuration defaults for
pytest and test coverage.
These configuration files are
.coveragerc, located at
the root of your package. Without these defaults, we would need to specify the
path to the module on which we want to run tests and coverage.
$VENV/bin/pytest --cov=myproject myproject/tests.py -q
.. seealso:: See ``pytest``'s documentation for :ref:`pytest:usage` or invoke ``pytest -h`` to see its full set of options.
.. index:: single: running an application single: pserve single: reload single: starting
Running the Project Application
.. seealso:: See also the output of :ref:`pserve --help <pserve_script>`.
Once a project is installed for development, you can run the application it
represents using the
pserve command against the generated configuration
file. In our case, this file is named
Here's sample output from a run of
pserve on Unix:
$VENV/bin/pserve development.ini Starting server in PID 77171. Serving on http://localhost:6543 Serving on http://localhost:6543
Access is restricted such that only a browser running on the same machine as
Pyramid will be able to access your Pyramid application. However, if you want
to open access to other machines on the same network, then edit the
development.ini file, and replace the
listen value in the
[server:main] section, changing it from
(this is equivalent to
0.0.0.0:6543 [::]:6543). For example:
[server:main] use = egg:waitress#main listen = *:6543
Now when you use
pserve to start the application, it will respond to
requests on all IP addresses possessed by your system, not just requests to
localhost. This is what the
serving on http://0.0.0.0:6543 means. The server will respond to requests
127.0.0.1 and on any external IP address. For example, your system
might be configured to have an external IP address
192.168.1.50. If that's
the case, if you use a browser running on the same system as Pyramid, it will
be able to access the application via
http://127.0.0.1:6543/ as well as via
http://192.168.1.50:6543/. However, other people on other computers on
the same network will also be able to visit your Pyramid application in their
browser by visiting
http://192.168.1.50:6543/. The same holds true if you use
[::] means the same as
0.0.0.0 but for IPv6 protocol.
You can change the port on which the server runs on by changing the same
portion of the
development.ini file. For example, you can change the
listen = localhost:6543 line in the
listen = localhost:8080 to run the server on port 8080 instead of port 6543.
You can shut down a server started this way by pressing
Ctrl-Break on Windows).
The default server used to run your Pyramid application when a project is
created from a cookiecutter is named :term:`Waitress`. This server is what prints
Serving on... line when you run
pserve. It's a good idea to use
this server during development because it's very simple. It can also be used
for light production. Setting your application up under a different server is
not advised until you've done some development work under the default server,
particularly if you're not yet experienced with Python web development. Python
web server setup can be complex, and you should get some confidence that your
application works in a default environment before trying to optimize it or make
it "more like production". It's awfully easy to get sidetracked trying to set
up a non-default server for hours without actually starting to do any
development. One of the nice things about Python web servers is that they're
largely interchangeable, so if your application works under the default server,
it will almost certainly work under any other server in production if you
eventually choose to use a different one. Don't worry about it right now.
For more detailed information about the startup process, see :ref:`startup_chapter`. For more information about environment variables and configuration file settings that influence startup and runtime behavior, see :ref:`environment_chapter`.
During development, it's often useful to run
pserve using its
--reload is passed to
pserve, changes to any Python
module your project uses will cause the server to restart. This typically
makes development easier, as changes to Python code made within a
:app:`Pyramid` application is not put into effect until the server restarts.
For example, on Unix:
$VENV/bin/pserve development.ini --reload Starting subprocess with file monitor Starting server in PID 16601. Serving on http://localhost:6543 Serving on http://localhost:6543
Now if you make a change to any of your project's
.py files or
files, you'll see the server restart automatically:
development.ini changed; reloading... -------------------- Restarting -------------------- Starting server in PID 16602. Serving on http://localhost:6543 Serving on http://localhost:6543
Changes to template files (such as
.mak files) won't cause the
server to restart. Changes to template files don't require a server restart as
long as the
pyramid.reload_templates setting in the
true. Changes made to template files when this setting is
will take effect immediately without a server restart.
.. index:: single: WSGI
Viewing the Application
Once your application is running via
pserve, you may visit
http://localhost:6543/ in your browser. You will see something in your
browser like what is displayed in the following image:
This is the page shown by default when you visit an unmodified
pyramid-cookiecutter-starter application in a browser.
.. index:: single: debug toolbar
The Debug Toolbar
If you click on the :app:`Pyramid` logo at the top right of the page, a new target window will open to present a debug toolbar that provides various niceties while you're developing. This logo will float above every HTML page served by :app:`Pyramid` while you develop an application, and allows you to show the toolbar as necessary.
If you don't see the Pyramid logo on the top right of the page, it means you're
browsing from a system that does not have debugging access. By default, for
security reasons, only a browser originating from
can see the debug toolbar. To allow your browser on a remote system to access
the server, add a line within the
[app:main] section of the
development.ini file in the form
debugtoolbar.hosts = X .X.X.X. For
example, if your Pyramid application is running on a remote system, and you're
browsing from a host with the IP address
192.168.1.1, you'd add something
like this to enable the toolbar when your system contacts Pyramid:
[app:main] # .. other settings ... debugtoolbar.hosts = 192.168.1.1
For more information about what the debug toolbar allows you to do, see the :ref:`documentation for pyramid_debugtoolbar <toolbar:overview>`.
The debug toolbar will not be shown (and all debugging will be turned off) when
you use the
production.ini file instead of the
development.ini ini file
to run the application.
You can also turn the debug toolbar off by editing
commenting out a line. For example, instead of:
Put a hash mark at the beginning of the
Then restart the application to see that the toolbar has been turned off.
Note that if you comment out the
pyramid_debugtoolbar line, the
must be in the first column. If you put it anywhere else, and then attempt
to restart the application, you'll receive an error that ends something like
ImportError: No module named #pyramid_debugtoolbar
.. index:: single: project structure
The Project Structure
pyramid-cookiecutter-starter cookiecutter generated a :term:`project` (named
which contains a Python :term:`package`. The package is also named
myproject; the cookiecutter generates a project which
contains a package that shares its name.
cookiecutter-generated projects share a similar structure.
myproject project we've generated has the following directory structure:
myproject ├── .coveragerc ├── .gitignore ├── CHANGES.txt ├── MANIFEST.in ├── myproject │ ├── __init__.py │ ├── routes.py │ ├── static │ │ ├── pyramid-16x16.png │ │ ├── pyramid.png │ │ └── theme.css │ ├── templates │ │ ├── 404.jinja2 │ │ ├── layout.jinja2 │ │ └── mytemplate.jinja2 │ ├── tests.py │ └── views │ ├── __init__.py │ ├── default.py │ └── notfound.py ├── README.txt ├── development.ini ├── production.ini ├── pytest.ini └── setup.py
myproject :term:`project` directory is the distribution and deployment
wrapper for your application. It contains both the
:term:`package` representing your application as well as files used to
describe, run, and test your application.
.coveragercconfigures coverage when running tests.
.gitignoretells git which files and directories to ignore from source code version control.
CHANGES.txtdescribes the changes you've made to the application. It is conventionally written in :term:`reStructuredText` format.
MANIFEST.inis a :term:`distutils` "manifest" file, naming which files should be included in a source distribution of the package when
python setup.py sdistis run.
README.txtdescribes the application in general. It is conventionally written in :term:`reStructuredText` format.
development.iniis a :term:`PasteDeploy` configuration file that can be used to execute your application during development.
production.iniis a :term:`PasteDeploy` configuration file that can be used to execute your application in a production configuration.
pytest.iniis a configuration file for running tests.
setup.pyis the file you'll use to test and distribute your application. It is a standard :term:`Setuptools`
.. index:: single: PasteDeploy single: ini file
development.ini file is a :term:`PasteDeploy` configuration file. Its
purpose is to specify an application to run when you invoke
pserve, as well
as the deployment settings provided to that application.
development.ini file looks like so:
.. literalinclude:: myproject/development.ini :language: ini :linenos:
This file contains several sections including
[server:main], and several other sections related to logging configuration.
[app:main] section represents configuration for your :app:`Pyramid`
use setting is the only setting required to be present in
[app:main] section. Its default value,
that our myproject project contains the application that should be served.
Other settings added to this section are passed as keyword arguments to the
main in our package's
__init__.py module. You can
provide startup-time configuration parameters to your application by adding
more settings to this section.
.. seealso:: See :ref:`pastedeploy_entry_points` for more information about the meaning of the ``use = egg:myproject`` value in this section.
pyramid.reload_templates setting in the
[app:main] section is a
:app:`Pyramid`-specific setting which is passed into the framework. If it
exists, and its value is
true, supported template changes will not require
an application restart to be detected. See :ref:`reload_templates_section` for
pyramid.reload_templates option should be turned off for
production applications, as template rendering is slowed when it is turned
pyramid.includes setting in the
[app:main] section tells Pyramid to
"include" configuration from another package. In this case, the line
pyramid.includes = pyramid_debugtoolbar tells Pyramid to include
configuration from the
pyramid_debugtoolbar package. This turns on a
debugging panel in development mode which can be opened by clicking on the
:app:`Pyramid` logo on the top right of the screen. Including the debug
toolbar will also make it possible to interactively debug exceptions when an
Various other settings may exist in this section having to do with debugging or influencing runtime behavior of a :app:`Pyramid` application. See :ref:`environment_chapter` for more information about these settings.
[app:main] signifies that this is the default
application run by
pserve when it is invoked against this configuration
file. The name
main is a convention used by PasteDeploy signifying that it
is the default application.
[server:main] section of the configuration file configures a WSGI
server which listens on TCP port 6543. It is configured to listen on localhost
The sections after
# logging configuration represent Python's standard
library :mod:`logging` module configuration for your application.
The default configuration
sends application logging output to the standard error output of your terminal.
For more information see :ref:`logging_chapter`.
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 :term:`WSGI` server
.. index:: single: production.ini
production.ini file is a :term:`PasteDeploy` configuration file with a
purpose much like that of
development.ini. However, it disables the debug
toolbar, and filters all log messages except those above the WARN level. It
also turns off template development options such that templates are not
automatically reloaded when changed, and turns off all debugging options. This
file is appropriate to use instead of
development.ini when you put your
application into production.
It's important to use
production.ini (and not
benchmark your application and put it into production.
configures your system with a debug toolbar that helps development, but the
inclusion of this toolbar slows down page rendering times by over an order of
magnitude. The debug toolbar is also a potential security risk if you have it
.. index:: single: MANIFEST.in
MANIFEST.in file is a :term:`distutils` configuration file which
specifies the non-Python files that should be included when a
:term:`distribution` of your Pyramid project is created when you run
setup.py sdist. Due to the information contained in the default
MANIFEST.in, an sdist of your Pyramid project will include
.rst files, graphics files, and template files, as well as
.py files. See
for more information about the syntax and usage of
Without the presence of a
MANIFEST.in file or without checking your source
code into a version control repository,
setup.py sdist places only Python
source files (files ending with a
.py extension) into tarballs generated
python setup.py sdist. This means, for example, if your project was not
checked into a Setuptools-compatible source control system, and your project
directory didn't contain a
MANIFEST.in file that told the
machinery to include
*.pt files, the
file would not be included in the generated tarball.
Projects generated by Pyramid cookiecutters include a default
MANIFEST.in file contains declarations which tell it to include files
*.js in the generated tarball. If you include
files with extensions other than the files named in the project's
MANIFEST.in and you don't make use of a Setuptools-compatible version
control system, you'll need to edit the
MANIFEST.in file and include the
statements necessary to include your new files. See
https://docs.python.org/2/distutils/sourcedist.html#principle for more
information about how to do this.
You can also delete
MANIFEST.in from your project and rely on a :term:`Setuptools`
feature which simply causes all files checked into a version control system to
be put into the generated 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 Subversion. After you do this, when you rerun
all files checked into the version control system will be included in the
tarball. If you don't use Subversion, and instead use a different version
control system, you may need to install a :term:`Setuptools` add-on such as
setuptools-hg for this behavior to work properly.
.. index:: single: setup.py
setup.py file is a :term:`Setuptools` setup file. It is meant to be
used to define requirements for installing dependencies for your package and
testing, as well as distributing your application.
setup.py is the de facto standard which Python developers use to
distribute their reusable code. You can read more about
and their usage in the Python Packaging User Guide and Setuptools documentation.
setup.py looks like this:
.. literalinclude:: myproject/setup.py :language: python :linenos:
setup.py file calls the :term:`Setuptools`
setup function, which does
various things depending on the arguments passed to
pip on the command
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 :term:`Setuptools` setup files, we'll provide a whirlwind tour of what exists in this file in this section.
Your application's name can be any string; it is specified in the
field. The version number is specified in the
version value. A short
description is provided in the
description field. The
is conventionally the content of the
CHANGES files appended
classifiers field is a list of Trove classifiers describing your
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.
indicates that this package is not safe to use as a zipped egg; instead it will
always unpack as a directory, which is more convenient.
indicates that this package depends on the
extras_require is a Python dictionary that defines what is required to be
installed for running tests. We examined
entry_points in our discussion of
development.ini file; this file defines the
main 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, when adding Python package
dependencies, or when versioning your application for your own use. For fun,
you can try this command now:
$VENV/bin/python setup.py sdist
This will create a tarball of your application in a
dist subdirectory named
myproject-0.0.tar.gz. You can send this tarball to other people who want
to install and use your application.
.. index:: single: package
__init__.pyfile signifies that this is a Python :term:`package`. It also contains code that helps users run the application, including a
mainfunction which is used as a entry point for commands such as
pviews, and others.
templatesdirectory, which contains :term:`Jinja2` (or other types of) templates.
tests.pymodule, which contains unit test code for the application.
routes.pymodule, which contains routing code for the application.
viewspackage, which contains view code for the application.
staticdirectory, which contains static files, including images and CSS.
These are purely conventions established by the cookiecutter. :app:`Pyramid` doesn't insist that you name things in any particular way. However, it's generally a good idea to follow Pyramid standards for naming, so that other Pyramid developers can get up to speed quickly on your code when you need help.
.. index:: single: __init__.py
We need a small Python module that configures our application and which
advertises an entry point for use by our :term:`PasteDeploy`
This is the file named
__init__.py. The presence of an
also informs Python that the directory which contains it is a package.
.. literalinclude:: myproject/myproject/__init__.py :language: python :linenos:
mainfunction configures the application.
Line 7 opens a context manager with an instance of a :term:`Configurator`.
Line 8 adds support for Jinja2 templating bindings, allowing us to specify renderers with the
Line 9 includes the
Line 10 calls
config.scan(), which picks up view registrations declared elsewhere in the package (in this case, in the
Line 11 returns a :term:`WSGI` application to the caller of the function (Pyramid's pserve).
.. seealso:: See :ref:`the_startup_process` for more about the application's :ref:`settings <startup_settings>` and ``main``\'s :ref:`arguments <startup_constructor_arguments>` and statements.
.. index:: single: routes.py
routes.py module gets included by the
main function in our
It registers a view and a route.
.. literalinclude:: myproject/myproject/routes.py :language: python :linenos:
Line 2 registers a static view, which will serve up the files from the
myproject:static :term:`asset specification` (the
static directory of the
Line 3 adds a :term:`route` to the configuration. This route is later used by a view in the
.. index:: single: views.py
Much of the heavy lifting in a :app:`Pyramid` application is done by view callables. A :term:`view callable` is the main tool of a :app:`Pyramid` web application developer; it is a bit of code which accepts a :term:`request` and which returns a :term:`response`.
Our project has a
views package by virtue of it being a directory containing an
__init__.py file happens to have no content, although it could as a project develops.
We have two view modules in the
Let's look at
.. literalinclude:: myproject/myproject/views/default.py :language: python :linenos:
Lines 4-6 define and register a :term:`view callable` named
my_view is decorated with a
view_config decorator (which
is processed by the
config.scan() line in our
view_config decorator asserts that this view be found when a :term:`route`
home is matched. In our case, because our
routes.py maps the
home to the URL pattern
/, this route will match when a
visitor visits the root URL. The view_config decorator 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.jinja2, which is an :term:`asset specification` that
mytemplate.jinja2 file within the
templates directory of the
myproject package. The asset specification could have also been specified
myproject:templates/mytemplate.jinja2; the leading package name and colon is
optional. The template file pointed to is a :term:`Jinja2` template
This view callable function is handed a single piece of information: the
:term:`request`. The request is an instance of the :term:`WebOb`
class representing the browser's request to our server.
This view is configured to invoke a :term:`renderer` on a template. The dictionary the view returns (on line 6) provides the value the renderer substitutes into the template when generating HTML. The renderer then returns the HTML in a :term:`response`.
Dictionaries provide values to :term:`template`s.
Now let's look at
.. literalinclude:: myproject/myproject/views/notfound.py :language: python :linenos:
This file is similar to
It merely returns a
404 response status and an empty dictionary to the template at
When the application is run with the cookiecutter's :ref:`default
development.ini <myproject_ini>` configuration, :ref:`logging is set up
<myproject_ini_logging>` to aid debugging. If an exception is raised,
uncaught tracebacks are displayed after the startup messages on :ref:`the
console running the server <running_the_project_application>`. Also
print() statements may be inserted into the application for debugging to
send output to this console.
development.ini has a setting that controls how templates are
- When set to
True(as in the cookiecutter
development.ini), changed templates automatically reload without a server restart. This is convenient while developing, but slows template rendering speed.
- When set to
False(the default value), changing templates requires a server restart to reload them. Production applications should use
pyramid.reload_templates = False.
.. seealso:: See also :ref:`views_which_use_a_renderer` for more information about how views, renderers, and templates relate and cooperate.
.. seealso:: Pyramid can also dynamically reload changed Python files. See also :ref:`reloading_code`.
.. seealso:: See also the :ref:`debug_toolbar`, which provides interactive access to your application's internals and, should an exception occur, allows interactive access to traceback execution stack frames from the Python interpreter.
.. index:: single: static directory
This directory contains static assets which support the
template. It includes CSS and images.
This is the base layout content. It contains a single marker for content block. Other templates inherit its content, providing layout for the web application. Its contents are too long to show here, but here is an excerpt:
.. literalinclude:: myproject/myproject/templates/layout.jinja2 :language: jinja :lines: 34-38 :lineno-match:
This is the content :term:`Jinja2` template that exists in the project. It is referenced by the call to
@view_config as the
my_view view callable in the
views/default.py file. See
:ref:`views_which_use_a_renderer` for more information about renderers. It inherits ("extends") the HTML provided by
layout.jinja2, replacing the content block with its own content.
.. literalinclude:: myproject/myproject/templates/mytemplate.jinja2 :language: jinja :linenos:
This template is similar to
mytemplate.jinja2, but with a few differences.
It is referenced by the call to
@notfound_view_config as the
renderer of the
notfound_view view callable in the
It inherits the HTML provided by
layout.jinja2, replacing the content block with its own content.
.. literalinclude:: myproject/myproject/templates/404.jinja2 :language: jinja :linenos:
.. index:: single: tests.py
tests.py module includes tests for your application.
.. literalinclude:: myproject/myproject/tests.py :language: python :linenos:
tests.py file has one unit test and one functional test defined
within it. These tests are executed when you run
pytest -q. You may add
more tests here as you build your application. You are not required to write
tests to use :app:`Pyramid`. This file is simply provided for convenience and
.. index:: pair: modifying; package structure
Modifying Package Structure
It is best practice for your application's code layout to not stray too much from accepted Pyramid cookiecutter defaults. If you refrain from changing things very much, other Pyramid coders will be able to more quickly understand your application. However, the code layout choices made for you by a cookiecutter are in no way magical or required. Despite the choices made for you by any cookiecutter, you can decide to lay your code out any way you see fit.
For example, the configuration method named
:meth:`~pyramid.config.Configurator.add_view` requires you to pass a
:term:`dotted Python name` or a direct object reference as the class or
function to be used as a view.
By default, the
starter cookiecutter would have you create a
views directory, and add a single file for each view or collection of related views.
However, you might be more comfortable creating a single
views.py module in your package and add view functions to it.
Whatever structure you prefer, as long as you use the
to register views in conjunction with
config.scan(), they will be picked up
automatically when the application is restarted.
Using the Interactive Shell
It is possible to use the
pshell command to load a Python interpreter
prompt with a similar configuration as would be loaded if you were running your
Pyramid application via
pserve. This can be a useful debugging tool. See
:ref:`interactive_shell` for more details.
What Is This
The code generated by a :app:`Pyramid` cookiecutter assumes that you will be using
pserve command to start your application while you do development.
pserve is a command that reads a :term:`PasteDeploy`
.ini file (e.g.,
development.ini), and configures a server to serve a :app:`Pyramid`
application based on the data in the file.
pserve is by no means the only way to start up and serve a :app:`Pyramid`
application. As we saw in :ref:`firstapp_chapter`,
pserve needn't be
invoked at all to run a :app:`Pyramid` application. The use of
run a :app:`Pyramid` application is purely conventional based on the output of
its cookiecutter. But we strongly recommend using
pserve while developing
your application because many other convenience introspection commands (such as
proutes, and others) are also implemented in
terms of configuration availability of this
.ini file format. It also
configures Pyramid logging and provides the
--reload switch for convenient
restarting of the server when code changes.
Using an Alternate WSGI Server
Pyramid cookiecutters generate projects which use the :term:`Waitress` WSGI server. Waitress is a server that is suited for development and light production usage. It's not the fastest nor the most featureful WSGI server. Instead, its main feature is that it works on all platforms that Pyramid needs to run on, making it a good choice as a default server from the perspective of Pyramid's developers.
Any WSGI server is capable of running a :app:`Pyramid` application. But we suggest you stick with the default server for development, and that you wait to investigate other server options until you're ready to deploy your application to production. Unless for some reason you need to develop on a non-local system, investigating alternate server options is usually a distraction until you're ready to deploy. But we recommend developing using the default configuration on a local system that you have complete control over; it will provide the best development experience.
One popular production alternative to the default Waitress server is
:term:`mod_wsgi`. You can use
mod_wsgi to serve your :app:`Pyramid` application
using the Apache web server rather than any "pure-Python" server like Waitress.
It is fast and featureful. See :ref:`modwsgi_tutorial` for details.
Another good production alternative is :term:`Green Unicorn` (aka
gunicorn). It's faster than Waitress and slightly easier to configure than
mod_wsgi, although it depends, in its default configuration, on having a
buffering HTTP proxy in front of it. It does not, as of this writing, work on
Automatically Reloading Your Code
During development, it can be really useful to automatically have the
webserver restart when you make changes.
pserve has a
to enable this. It uses the
to enable this behavior. When your code crashes,
hupper will wait for
another change or the
SIGHUP signal before restarting again.
hupper will poll the filesystem for changes to all Python
code. This can be pretty inefficient in larger projects. To be nicer to your
hard drive, you should install the
watchdog package in development.
hupper will automatically use
watchdog to more efficiently poll the
Monitoring Custom Files
pserve --reload will monitor all imported Python code
sys.modules) as well as the config file passed to
development.ini). You can instruct
pserve to watch
other files for changes as well by defining a
[pserve] section in your
configuration file. For example, let's say your application loads the
favicon.ico file at startup and stores it in memory to efficiently
serve it many times. When you change it, you want
pserve to restart:
[pserve] watch_files = myproject/static/favicon.ico
Paths may be absolute or relative to the configuration file. They may also
be an :term:`asset specification`. These paths are passed to
has some basic support for globbing. Acceptable glob patterns depend on the
version of Python being used.