edc-device

edc-device provides device roles unique device IDs for hosts and clients where the hostname may not be reliable. Hosts can be group as servers, clients, node_servers and some of their functionality limited according to this role.

A unique device ID is used to seed unique subject and sample identifiers. Uniqueness is evaluated during deployment.

Device information is set in and read from edc_device.apps.AppConfig.

You should subclass into your projects apps.py like this, for example:

from edc_device.apps import AppConfig as EdcDeviceAppConfigParent

class EdcDeviceAppConfig(EdcDeviceAppConfigParent):
    device_id = '32'
    device_role = CLIENT
    device_permissions = DevicePermissions(
        plot_add, plot_change, ...)

... and then in your settings:

INSTALLED_APPS = [
    ...
    my_app.apps.EdcDeviceAppConfig,
    myapp.apps.AppConfig',
]

Include in your urls.py:

urlpatterns = [
    ...
    path('edc_device/', include('edc_device.urls')),
    ...
]

To get to the Edc Device home page, reverse the url like this:

reverse('edc_device:home_url')

Usage

A client might look like this:

class EdcDeviceAppConfig(EdcDeviceAppConfigParent):
    device_id = '18'
	node_server_id_list = [97, 98, 99]
	middleman_id_list = [95, 96]

>>> from django.apps import apps as django_apps
>>> app_config = django_apps.get_app_config('edc_device')
>>> app_config.device_id
'18'
>>> app_config.is_client
True
>>> app_config.device_role
'Client'

A node server server might look like this:

class EdcDeviceAppConfig(EdcDeviceAppConfigParent):
    device_id = '98'
    node_server_id_list = [97, 98, 99]
    middleman_id_list = [95, 96]

>>> from django.apps import apps as django_apps
>>> app_config = django_apps.get_app_config('edc_device')
>>> app_config.device_id
'98'
>>> app_config.is_node_server
True
>>> app_config.device_role
'NodeServer'

A middleman server might look like this:

class EdcDeviceAppConfig(EdcDeviceAppConfigParent):
    device_id = '95'
    node_server_id_list = [97, 98, 99]
    middleman_id_list = [95, 96]

>>> from django.apps import apps as django_apps
>>> app_config = django_apps.get_app_config('edc_device')
>>> app_config.device_id
'95'
>>> app_config.is_middleman
True
>>> app_config.device_role
'Middleman'

The central server might look like this:

class EdcDeviceAppConfig(EdcDeviceAppConfigParent):
    device_id = '99'
    node_server_id_list = [97, 98, 99]
    middleman_id_list = [95, 96]

>>> from django.apps import apps as django_apps
>>> app_config = django_apps.get_app_config('edc_device')
>>> app_config.device_id
'99'
>>> app_config.is_middleman
True
>>> app_config.device_role
'CentralServer'

See also edc_sync.

Device Permissions by Model

You can use the device role, or the device ID, to limit ADD/CHANGE permissions on a model.

edc-device AppConfig maintains a collection of DeviceAddPermission and DeviceChangePermission instances that are inspected in the save method of a model using the DeviceModelMixin.

To declare a DeviceAddPermission object:

test_model_add = DeviceAddPermission(
    model='my_app.mymodel, device_roles=[NODE_SERVER, CENTRAL_SERVER])

To declare a DeviceChangePermission object:

test_model_change = DeviceChangePermission(
    model='my_app.mymodel, device_roles=[CLIENT])

This means that if app_config.device_role is anything other than NODE_SERVER or CENTRAL_SERVER, the save method will raise a DevicePermissionsAddError.

To register the instances with edc_device.apps.AppConfig.device_permissions:

device_permissions = DevicePermissions(test_model_add, test_model_change)

This means that if app_config.device_role is anything other than CLIENT, the save method will raise a DevicePermissionsChangeError.

On boot up you should see:

Loading Edc Device ...
  * device id is '10'.
  * device role is 'Client'.
  * device permissions exist for:
    - edc_device.testmodel ADD NodeServer,CentralServer
    - edc_device.testmodel CHANGE Client
Done loading Edc Device.

Models declared with the EdcDeviceModelMixin check the device permissions collection on save. Note the model mixin is already declared with BaseUuidModel.

from edc_base.model_mixins import BaseUuidModel

class TestModel(BaseUuidModel):
    pass

Declaring device permissions directly on model Meta class:

You can declare device permissions on Meta.device_permissions in the same way as above.

[...]
class Meta(DeviceModelMixin.Meta):
    device_permissions = DevicePermissions(...)

Both Meta and AppConfig device permissions will be called, where the Meta class object will be called first.

Disable device permissions by model instance:

You can disable device permissions per model instance by setting check_device_permissions to False

Customizing Device Permissions

The ADD and CHANGE device permission objects by default inspect the model's id. If obj.id is None, it as an ADD model operation; If obj.id is not None, it is a CHANGE model operation.

You can change this by overriding the model_operation method. The model_operation must return None or some value, such as self.label.

For example:

# default for DeviceAddPermission
label = 'ADD'

def model_operation(self, model_obj=None, **kwargs):
    if not model_obj.id:
        return self.label
    return None

# overridden
def model_operation(self, model_obj=None, **kwargs):
    """Return ADD if both id and plot identifier are None.
    """
    if not model_obj.id and not obj.plot_identifier:
        return self.label
    return None