baymodel-update command is not there in python-client but internally code is there in magnum api and magnum conductor for baymodel-update command.
root@PRINHYLTPHP0400:/home/devstack/devstack# magnum help
usage: magnum [--version] [--debug] [--os-cache]
[--os-region-name <region-name>]
[--os-tenant-id <auth-tenant-id>]
[--service-type <service-type>]
[--endpoint-type <endpoint-type>]
[--magnum-api-version <magnum-api-ver>]
[--os-cacert <ca-certificate>] [--bypass-url <bypass-url>]
[--os-auth-system <auth-system>] [--os-username <username>]
[--os-password <password>] [--os-tenant-name <tenant-name>]
[--os-token <token>] [--os-auth-url <auth-url>]
<subcommand> ...
Command-line interface to the OpenStack Magnum API.
Positional arguments:
<subcommand>
bay-create Create a bay.
bay-delete Delete specified bay.
bay-list Print a list of available bays.
bay-show Show details about the given bay.
bay-update Update information about the given bay.
baymodel-create Create a baymodel.
baymodel-delete Delete specified baymodel.
baymodel-list Print a list of bay models.
baymodel-show Show details about the given baymodel.
coe-service-create Create a coe service.
coe-service-delete Delete specified coe service(s).
Try 'magnum help baymodel-create' for more information.
root@PRINHYLTPHP0400:/home/devstack/devstack# magnum baymodel-update
usage: magnum [--version] [--debug] [--os-cache]
[--os-region-name <region-name>]
[--os-tenant-id <auth-tenant-id>]
[--service-type <service-type>]
[--endpoint-type <endpoint-type>]
[--magnum-api-version <magnum-api-ver>]
[--os-cacert <ca-certificate>] [--bypass-url <bypass-url>]
[--os-auth-system <auth-system>] [--os-username <username>]
[--os-password <password>] [--os-tenant-name <tenant-name>]
[--os-token <token>] [--os-auth-url <auth-url>]
<subcommand> ...
error: argument <subcommand>: invalid choice: u'baymodel-update'
Try 'magnum help ' for more information.
By design Api and conductor both can access db.