Circuit termination API error: Cannot assign "<Provider: IGN>": "CircuitTermination.provider_network" must be a "ProviderNetwork" instance.

NetBox version

2.12.2

Python version

3.8

Steps to Reproduce

Via API only POST to /circuits/circuit-terminations/ when using a ProviderNetwork, example:

{
  "circuit": 2,
  "term_side": "Z",
  "provider_network": 1
}

Expected Behavior

HTTP response 201 and the new termination created

Observed Behavior

HTTP response 500

{
    "error": "Cannot assign \"<Provider: IGN>\": \"CircuitTermination.provider_network\" must be a \"ProviderNetwork\" instance.",
    "exception": "ValueError",
    "netbox_version": "2.11.2",
    "python_version": "3.8.8"
}

I managed to solve it internally by modifying

netbox/netbox/circuits/api/nested_serializers.py

Line 23 in 9e5d41c

model = Provider

to

model = ProviderNetwork