Problem

PodOS/mashlib cannot create new resources because 404 responses don't include the headers that tell rdflib what editing protocols are supported.

When rdflib tries to create a new resource, it first does a GET to check if it exists. If it gets a 404 without Accept-Patch and Accept-Put headers, it doesn't know how to create the resource.

Error from PodOS:

Can't create new resources with PodOS. You may need to add accept-patch header to 404 resources, so that rdflib can figure out how to create it.
Exception in update: Error: Update: Loaded http://localhost:3210/something-new but still can't figure out what editing protocol it supports.

Solution

Add Accept-Patch, Accept-Put, and Allow headers to all 404 responses so clients know what methods are available for creating resources.

Headers added to 404 responses:

• Accept-Patch: text/n3, application/sparql-update
• Accept-Put: application/ld+json, text/turtle, */*
• Allow: GET, HEAD, PUT, PATCH, OPTIONS
• Link: <resource.acl>; rel="acl"
• CORS headers

Affected handlers

• handleGet - GET requests for non-existent resources
• handleHead - HEAD requests for non-existent resources
• handleDelete - DELETE requests for non-existent resources
• handlePatch - PATCH requests for non-existent resources