Multiple Controllers With Same Label

There are many ways to use controllers. In some circumstances you might find that you want to have two controllers with the same label but stacked on different parent controllers. This is a problem because controller labels must be unique.

Take for example the situation where you want to have a ‘list’ controller, rather than a ‘list’ function of another controller. You might call this as:

$ myapp <controller1> <list_controller>

$ myapp <controller2> <some_other_list_controller>

In both cases, you would probably want the ‘sub-controller’ or sub-command to be ‘list’. This is possible with the use of the ‘aliases’ and ‘aliases_only’ Meta options. Take the following code as an example where we have a ‘users’ and a ‘hosts’ controller and we want to have a ‘list’ sub-command under both:

from cement.core.foundation import CementApp
from cement.core.controller import CementBaseController, expose

# define application controllers
class MyAppBaseController(CementBaseController):
    class Meta:
        label = 'base'

class UsersController(CementBaseController):
    class Meta:
        label = 'users'
        description = "this is the users controller"
        stacked_on = 'base'
        stacked_type = 'nested'

class HostsController(CementBaseController):
    class Meta:
        label = 'hosts'
        description = "this is the hosts controller"
        stacked_on = 'base'
        stacked_type = 'nested'

class UsersListController(CementBaseController):
    class Meta:
        label = 'users_list'
        description = 'list all available users'
        aliases = ['list']
        aliases_only = True
        stacked_on = 'users'
        stacked_type = 'nested'

    @expose(hide=True)
    def default(self):
        print "Inside UsersListController.default()"

class HostsListController(CementBaseController):
    class Meta:
        label = 'hosts_list'
        description = 'list all available hosts'
        aliases = ['list']
        aliases_only = True
        stacked_on = 'hosts'
        stacked_type = 'nested'

    @expose(hide=True)
    def default(self):
        print "Inside HostsListController.default()"

class MyApp(CementApp):
    class Meta:
        label = 'myapp'
        handlers = [
            MyAppBaseController,
            UsersController,
            HostsController,
            UsersListController,
            HostsListController,
            ]

def main():
    with MyApp() as app:
        app.run()

if __name__ == '__main__':
    main()

$ python myapp.py --help
usage: myapp.py (sub-commands ...) [options ...] {arguments ...}

Base Controller

commands:

  hosts
    this is the hosts controller

  users
    this is the users controller

optional arguments:
  -h, --help  show this help message and exit
  --debug     toggle debug output
  --quiet     suppress all output


$ python myapp.py users --help
usage: myapp.py (sub-commands ...) [options ...] {arguments ...}

this is the users controller

commands:

  list
    list all available users

optional arguments:
  -h, --help  show this help message and exit
  --debug     toggle debug output
  --quiet     suppress all output


$ python myapp.py users list
Inside UsersListController.default()

$ python myapp.py hosts list
Inside HostsListController.default()