Create custom fields that are computed based on referencing other data

[jedelman8]

Proposed Functionality

Read-only computed custom fields using existing data already stored in the database. This will allow users to be able to build lightweight Jinja (or Python) templates to populate a read-only custom field value.

Use Case

As a user, I want to dynamically generate interface descriptions using device, neighboring device, circuit, or circuit ID. All data already stored in Nautobot, I should be able to use Jinja templating, similar to custom links, to build that string thus simplifying the network configuration templates that are used to generate full configurations. As a user, I should be able to auto-generate fields that are required by automation systems like Ansible, e.g. ansible_network_os being "{{ vendor }}.{{ os }}.{{ os }}".

Database Changes

Will require some sort of database record to define and store these templates. Probably a new model as the existing custom-fields model is not directly applicable.

External Dependencies

None.

[jifox]

Is there also a possibilty to add such functionality to interface templates?

For e.g. a stacked switch has 48 Ports that have a name that depends on chassis nr

Gi1/0/[1-48] for switch 1
Gi2/0/[1-48] for switch 2

so to define

Gi{% chassis_nr %}/0/[1-48]

[jedelman8]

@jifox Where would chassis_nr be defined in this example? Proposing to use a custom field to define the number and then use that in the template?

[jifox]

@jedelman8 It should reference the Position field of Members to Virtual Chassis

[jifox]

@jedelman8 with a default value of 1

[jfach]

I'll take this one!

[dgarros]

I think we should be good to close this one

[glennmatthews]

Fixed by #577