Python Pyramid – Quick Guide
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Python Pyramid – Overview
Pyramid is an open source, WSGI compliant web framework written in Python. Initially the project named as Pylons, but later released under the new name Pyramid.
Pyramid is a minimalistic web framework. It doesn”t come packaged with any templating library or doesn”t have support for any specific database packages.
However, it can be integrated both with SQL databases via SQLAlchemy and with the Zope Object Database, as well as other NoSQL databases such as CouchDB.
Pyramid can also be configured to work with templating libraries such as Mako, Jinja2 or Chameleon.
Pyramid has been developed by Chris McDonough. The first version of Pyramid was released in January 2011. The latest version, Pyramid 2.0 has been released in March 2021.
Comparison with Other Python Frameworks
Pyramid web application framework is inspired by Zope and Django frameworks. As a result, it combines the best provisions of the two.
Pyramid is largely based on repose.bfg framework. After it was merged with the Pylons project, the same was renamed as Pyramid in 2010.
The ability to extend Pyramid application is borrowed from Zope library. Without modifying the application code, the application can be reused, modified or extended. The features such as declarative security layer and traversal of routes is inherited from Zope.
As is the case of Pylons 1.0, Pyramid doesn”t enforce any policy. It also lets the user choose any database or templating system The URL dispatch approach is also inspired by Pylons.
The concept of views is based on similar approach of Django. Extensive documentation is also a Django features adapted by Pyramid.
Although the definition doesn”t fit exactly, Pyramid can be said to follow MVC (Model-View-Controller) approach.
Python Pyramid – Environment Setup
It is recommended that the Pyramid package be installed on a system having Python 3.6 or above version installed. Pyramid can be installed on Linux, MacOS as well as Windows platform. Simplest way of installing it is by using PIP installer, preferably under a Python virtual environment.
pip3 install pyramid
Although a Pyramid web application can be run using the built-in WSGI development server that is a part of the wsgiref module, it is not recommended for use in production environment. Hence, we also install Waitress, a production-quality pure-Python WSGI server (also a part of Pylons project).
pip3 install waitress
This will install Pyramid (ver 2.0), Waitress (ver 2.1.2) in addition to other dependencies from Pylon project such that WebOb, PasteDeploy, and others. To check what gets installed, run pip freeze command.
pip3 freeze
hupper==1.10.3
PasteDeploy==2.1.1
plaster==1.0
plaster-pastedeploy==0.7
pyramid==2.0
translationstring==1.4
venusian==3.0.0
waitress==2.1.2
WebOb==1.8.7
zope.deprecation==4.4.0
zope.interface==5.4.0
Python Pyramid – Hello World
Example
To check whether Pyramid along with its dependencies are properly installed, enter the following code and save it as hello.py, using any Python-aware editor.
from wsgiref.simple_server import make_server
from pyramid.config import Configurator
from pyramid.response import Response
def hello_world(request):
return Response(”Hello World!”)
if __name__ == ”__main__”:
with Configurator() as config:
config.add_route(”hello”, ”/”)
config.add_view(hello_world, route_name=”hello”)
app = config.make_wsgi_app()
server = make_server(”0.0.0.0”, 6543, app)
server.serve_forever()
The Configurator object is required to define the URL route and bind a view function to it. The WSGI application object is obtained from this config object is an argument to the make_server() function along with the IP address and port of localhost. The server object enters a listening loop when serve_forever() method is called.
Run this program from the command terminal as.
Python hello.py
Output
The WSGI server starts running. Open the browser and enter http://loccalhost:6543/ in the address bar. When the request is accepted, the hello_world() view function gets executed. It returns the Hello world message. The Hello world message will be seen in the browser window.
As mentioned earlier, the development server created by make_server() function in the wsgiref module is not suited for production environment. Instead, we shall use Waitress server. Modify the hello.py as per the following code −
from pyramid.config import Configurator
from pyramid.response import Response
from waitress import serve
def hello_world(request):
return Response(”Hello World!”)
if __name__ == ”__main__”:
with Configurator() as config:
config.add_route(”hello”, ”/”)
config.add_view(hello_world, route_name=”hello”)
app = config.make_wsgi_app()
serve(app, host=”0.0.0.0”, port=6543)
All other functionality is same, except we use serve() function of waitress module to start the WSGI server. On visiting the ”/” route in the browser after running the program, the Hello world message is displayed as before.
Instead of a function, a callable class can also be used as a view. A callable class is the one which overrides the __call__() method.
from pyramid.response import Response
class MyView(object):
def __init__(self, request):
self.request = request
def __call__(self):
return Response(”hello world”)
Python Pyramid – Application Configuration
The Pyramid application object has an application registry that stores mappings of view functions to routes, and other application-specific component registrations. The Configurator class is used to build the application registry.
The Configurator life cycle is managed by a context manager that returns an application object.
with Configurator(settings=settings) as config:
#configuration methods
app = config.make_wsgi_app()
The Configurator class defines the following important methods to customize the application −
add_route()
This method registers a route for URL dispatch. Following arguments are used −
name − The first required positional argument must be a unique name for the route. The name is used to identify the route when registering views or generating URLs.
pattern − The second required positional argument is a string representing the URL path optionally containing variable placeholders for parsing the variable data from the URL. The placeholders are surrounded by curly brackets. For example, “/students/{id}”.
request_method − The value can be one of “GET”, “POST”, “HEAD”, “DELETE”, “PUT”. Requests only