Dynamic assignment object field

[SaschaSchwarzK]

Plugin Version

0.2.0

Proposed functionality

Allow a object field that relates to dynamically assigned objects.
Instead of having a m2m field, similar to the assignment of a config template, a filter should be defined that then queries the DB for matching objects.
For performance reasons those object fields could be excluded from table views.

Use case

Create a custom object for a maintenance contract and assign devices dynamically by a filter, rather then build real DB relations for each device.

External dependencies

none

[arthanson]

@SaschaSchwarzK can you please expand on what you are asking for here, or an example. I'm not sure exactly what you are asking for here.

[SaschaSchwarzK]

@arthanson What I had in mind is something like this.

Create a new object type DynamicAssigment very similar to the ConfigContext model from extras with all the different fields for tenant, site, device type etc. This defines a filter and has a function to return matching objects via a queryset manager. But with the difference that we don`t have a "data" JSON field.

class DynamicAssignment(SyncedDataMixin, CloningMixin, CustomLinksMixin, ChangeLoggedModel):
    """
    A DynamicAssignment represents a set of arbitrary data available to any Object matching its assigned
    qualifiers (region, site, etc.). For example, objects match to a filter defined in a DynamicAssignment will be available thru a  queryset manager.
    """
    name = models.CharField(
        verbose_name=_('name'),
        max_length=100,
        unique=True
    )
    weight = models.PositiveSmallIntegerField(
        verbose_name=_('weight'),
        default=1000
    )
    description = models.CharField(
        verbose_name=_('description'),
        max_length=200,
        blank=True
    )
    regions = models.ManyToManyField(
        to='dcim.Region',
        related_name='+',
        blank=True
    )
    site_groups = models.ManyToManyField(
        to='dcim.SiteGroup',
        related_name='+',
        blank=True
    )
    sites = models.ManyToManyField(
        to='dcim.Site',
        related_name='+',
        blank=True
    )
    locations = models.ManyToManyField(
        to='dcim.Location',
        related_name='+',
        blank=True
    )
    device_types = models.ManyToManyField(
        to='dcim.DeviceType',
        related_name='+',
        blank=True
    )
    roles = models.ManyToManyField(
        to='dcim.DeviceRole',
        related_name='+',
        blank=True
    )
.
.
.

And to make it more versatile we could also add an object_types field similar to the one in EventRule model. That would allow to assign any type of objects, not just devices and VMs as it was done with ConfigContext.

object_types = models.ManyToManyField(
        to='core.ObjectType',
        related_name='dynamic_assigment',
        verbose_name=_('object types'),
        help_text=_("The object(s) to which this assignment applies.")
    )

This would then be a helper object to the CustomObjectTypeField, like the CustomFieldChoiceSet is for the CustomField.

Then in the CustomObjectTypeField we could add a relation field to the DynamicAssignment object similar to the choice_set field that points to the CustomFieldChoiceSet object:

dynamic_assignment = models.ForeignKey(
        to="extras.DynamicAssignment",
        on_delete=models.PROTECT,
        related_name="dynamic_assigned_objects",
        verbose_name=_("dynamic assignment"),
        blank=True,
        null=True,
    )

I think that would be extremely power full to have this option. Way more effective that having thousands of relations stored as FK or M2M in the DB with the other field options. This becomes super handy when you deal with thousands of objects that you want to "assign" to a custom object.