python - There is a way to add features to an existing django command?

Question

I want to run a command just before the a django command is started.

For example:

$ python manage.py runserver
Validating models...

0 errors found
Django version 1.3, using settings 'creat1va.settings'
Development server is running at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
(started some command in the background)
[10/Jul/2011 21:50:26] "GET / HTTP/1.1" 200 1611
[10/Jul/2011 21:50:26] "GET /assets/css/master.css HTTP/1.1" 404 1783
[10/Jul/2011 21:50:26] "GET /assets/images/misc/logo.png HTTP/1.1" 404 1801
[10/Jul/2011 21:50:26] "GET /assets/images/icons/bo.gif HTTP/1.1" 404 1798
[10/Jul/2011 21:50:28] (My background process) "Some nice Feedback"

The main idea is to start a background process, and output the logging.

Is there a way to achieve this, without hacking the django sources?

Answer 1

Just realize that you can override the commands just easily as making an app with a command with the same name.

So I create an app and create a file with the same name as runserver, and later on that extend the runserver base class to add a new feature before it runs.

For example, I want to run the command $ compass watch, just before runserver starts and keep it running along runserver execution.

"""
Start $compass watch, command when you do $python manage.py runserver

file: main/management/commands/runserver.py

Add ′main′ app to the last of the installed apps
"""

from optparse import make_option
import os
import subprocess

from django.core.management.base import BaseCommand, CommandError
from django.core.management.commands.runserver import BaseRunserverCommand
from django.conf import settings

class Command(BaseRunserverCommand):
    option_list = BaseRunserverCommand.option_list + (
        make_option('--adminmedia', dest='admin_media_path', default='',
            help='Specifies the directory from which to serve admin media.'),
        make_option('--watch', dest='compass_project_path', default=settings.MEDIA_ROOT,
            help='Specifies the project directory for compass.'),
    )

    def inner_run(self, *args, **options):
        self.compass_project_path = options.get('compass_project_path', settings.MEDIA_ROOT)

        self.stdout.write("Starting the compass watch command for %r
" % self.compass_project_path)
        self.compass_pid = subprocess.Popen(["compass watch %s" % self.compass_project_path],
            shell=True,
            stdin=subprocess.PIPE,
            stdout=self.stdout,
            stderr=self.stderr)
        self.stdout.write("Compas watch process on %r
" % self.compass_pid.pid)

        super(Command, self).inner_run(*args, **options)

This works just fine.

Look at https://docs.djangoproject.com/en/dev/howto/custom-management-commands/ for more details about django commands

Hope someone find this helpful