Contract Assignment¶
A generic-FK link between a Contract and any Nautobot object that has a UUID PK. One model handles Contract-to-Device, Contract-to-Circuit, Contract-to-VirtualMachine, Contract-to-Tenant, etc. without per-target-type tables.
Fields¶
| Field | Type | Notes |
|---|---|---|
contract |
FK Contract | Parent contract. CASCADE on delete. |
content_type |
FK ContentType | Type of the assigned object. |
object_id |
UUID | PK of the assigned object. |
object |
GenericForeignKey | Resolved at access time. |
coverage_start |
date | When coverage of this target begins. Null = follows the contract's start_date. |
coverage_end |
date | When coverage of this target ends. Null = follows the contract's end_date. |
scope_notes |
string | Optional qualifier (e.g. "chassis only, not modules"; "firmware updates excluded"). |
is_primary |
bool | When the same target is covered by multiple contracts, this flag picks the primary one for display / on-call routing. |
Why a generic FK rather than per-target M2M?¶
Vendor support contracts typically cover a fleet — devices, circuits, virtual machines, sometimes a whole tenant or location. Modeling this as a Device M2M would mean separate models for every assignable target type. The generic FK lets one ContractAssignment row cover any Nautobot model with a UUID PK (which is every Nautobot model).
Why subclass PrimaryModel rather than BaseModel?¶
NautobotModelForm requires RelationshipModelMixin, which PrimaryModel provides but BaseModel doesn't. Phase 2's earlier BaseModel choice 500'd the create form. Promoting to PrimaryModel matches Nautobot's own ContactAssociation model — the canonical GFK-link pattern.
Constraints¶
UniqueConstraint(contract, content_type, object_id)— one assignment per (contract, target) pair.
Indexes¶
(content_type, object_id)— speeds up the transitive coverage query that joins on the GFK target.
Transitive coverage¶
The helpers.coverage_assignments(target) helper walks (self, tenant, location, rack, device) ancestry and returns all assignments covering the target — including ones attached at the Tenant or Location level. A Tenant-level contract assignment automatically covers every Device under that Tenant.
See Using the App — Coverage Gaps for the operator-facing surface.
Extras features enabled¶
custom_fields, custom_links, custom_validators, export_templates, graphql, relationships, webhooks.