Provide Hook or Flag for _get_links Behaviour

[mverteuil]

There is a bit of cleverness in _get_links that looks for a common prefix and extracts it into tags. This behaviour causes unpredictable results in the encoded schema if a variety of top level items used in different contexts are not displayed to a user based on their permissions.

For example:

User A has access to:

• /api/vegetables/seedless/ (SeedlessVegetableListCreateAPIView)
• /api/vegetables/seeded/(SeededVegetableListCreateAPIView)
• /api/protein/beef (BeefListCreateAPIView)

User B has access to:

• /api/vegetables/seedless/
• /api/vegetables/seeded/

The result is that User A's schema will have different operationId values than User B, which means my client code breaks depending on which user is accessing the encoded spec.

The default implementation in SchemaGenerator will cut off the /api prefix which is fine, but the problem stems from the fact that User B does not have access to /api/protein/beef.

This means the resulting operationIds and tags for User A are:

url	tags	operationId
/api/vegetables/seedless/	vegetables	seedless_create
/api/vegetables/seedless/	vegetables	seedless_list
/api/vegetables/seeded/	vegetables	seeded_create
/api/vegetables/seeded/	vegetables	seeded_list
/api/protein/beef/	protein	beef_create
/api/protein/beef/	protein	beef_list

However User B has:

url	tags	operationId
/api/vegetables/seedless/	seedless	seedless_create
/api/vegetables/seedless/	seedless	seedless_list
/api/vegetables/seeded/	seeded	seeded_create
/api/vegetables/seeded/	seeded	seeded_list

If I try to use the Swagger JS client, due to the variations in the schema, the path changes depending on which user is logged in which is extremely frustrating. This should be configurable by hook or flag, as I'm currently forced to leverage mock.patch to replace openapi_codec.encode._get_links which is horribly fragile and obviously undesired in production code.

For reference, my current solution is to eliminate the section where tags are determined which allows me to route all of my operations through a common operationId, regardless of the level of access the request user has.

def _get_links(document):
    """
    Monkey patch for openapi_codec.encode._get_links

    Implementation removes cleverness in openapi_codec.encode._get_links which tries to reduce
    the size of operation names by removing what it assumes to be redundancies.

    This is not suitable for our case, since the contents of our schemata vary depending on the
    access level of the request user.

    This patch may be applied with a context manager during OpenAPI document rendering.
    """
    # Extract all the links from the first or second level of the document.
    links = []
    for keys, link in get_links_from_document(document):
        operation_id = '_'.join(keys)
        links.append((operation_id, link, []))
    return links