Write your own command

The structure of a Django Chuck command is nearly the same as a Django command. You create a new command class in django_chuck.commands that inherits from BaseCommand, define your arguments, a help message and a handle function that will get called to run the command.

The parameter will get parsed by argparse so you can use all options described on the argparse pydoc page. It’s important that you set the parameters in __init__ otherwise all commands would get them!

The handle function will get two parameters args, the parsed command line arguments, and cfg, a dictionary of all config settings. Just pass them to the constructor of the BaseCommand and you will always get either the arg value or config value if you call the property directly on your command object.

Let’s say you define a new parameter myurl the user will automatically be allowed to set it either on the command line or in his config file by defining the dest value. You don’t have to care where the parameter comes from you can just call self.myurl and will get the arg value, config value or None.

The BaseCommand class also gives you some helper functions.

Function	Description
execute_in_project(cmd)	Loads virtualenv and django settings and executes the given cmd
db_cleanup	Delete django tables for complete db import
load_fixtures(file)	Load the given fixture file

You want to do some cleanup after a system failure or user interruption? Just implement the method signal_handler and do what ever you want to do. By default the project directory and the virtualenv directory will get erased automatically if the user doesnt set delete_project_on_failure to False in the config file.

Here is a complete example:

import os
from django_chuck.commands.base import BaseCommand
from django_chuck.commands import sync_database, migrate_database

class Command(BaseCommand):
    help = "Sync, migrate database and load fixtures"

    def __init__(self):
        super(Command, self).__init__()

        self.opts.append(("fixture_files", {
            "help": "Comma separated list of fixture files to load",
            "nargs": "?",
        }))

        self.opts.append(("my_dir", {
            "help": "My work dir to do something in there",
            "nargs": "?",
        }))


  def signal_handler(self):
      if os.path.exists(self.my_dir):
          print "Deleting directory " + self.my_dir
          shutil.rmtree(self.my_dir)


    def handle(self, args, cfg):
        super(Command, self).handle(args, cfg)

        sync_database.Command().handle(args, cfg)
        migrate_database.Command().handle(args, cfg)

        if self.fixture_files:
            for fixture_file in self.fixture_files.split(","):
                self.db_cleanup()
                self.load_fixtures(os.path.join(self.site_dir, "fixtures", fixture_file))