New part creation via API?

[Gajillion]

Hello. Can someone post a working data payload for creating a part via the API? I've tried every possible permutation I can and get the same error every time.

{
"@id": "/api/errors/400",
"@type": "hydra:Error",
"title": "An error occurred",
"detail": "You tried to create a new entity through the relation 'App\Entity\Parts\Part#category', but this is not allowed. Please create the entity first and then reference it through an IRI!",
"status": 400,
"type": "/errors/400",
"hydra:title": "An error occurred",
"hydra:description": "You tried to create a new entity through the relation 'App\Entity\Parts\Part#category', but this is not allowed. Please create the entity first and then reference it through an IRI!"
}

[Gajillion]

Never mind. Just having one of those days...

curl -X 'POST'
'http://xxxxxx/api/parts'
-H 'accept: application/json'
-H 'Content-Type: application/json'
-d '{
"name": "myname",
"category": "/api/categories/10"
}'