Spec for Paging that supports header extraction

Right now pageable supports the following syntax: https://github.com/Azure/autorest/blob/master/docs/extensions/readme.md#x-ms-pageable

"x-ms-pageable": {
   "nextLinkName": "nextLink",
   "itemName": "values",
   "operationName": "Paging_nextOperationWithQueryParams" 
},

And nextLinkName is the name of a JSON key at the root of the returned JSON payload.

We want to be able to extract that nextLink from a header instead.

Proposition:

• Adding a nextLinkIsHeader: bool parameter, to say that nextLinkName is a header name from returned headers.
• By default value is “false” (meaning comes from JSON)

Alternative proposition (that I prefer less):

• Adding nextLinkOrigin: str parameter, that states the origin using in vocab from Swagger (body/query/header) I prefer it less, because I think it’s overcomplicated, since except body/headers there is not that much possibility anyway.

This is needed for synapse, so I’d like to move fast on it and make it happen fast. I don’t expect a lot of work on the m4 side (pass it through).

[daviwil]

Yep, that looks better to me! I prefer to err on the side of future extensibility when it’s not very intrusive, like this case.

[joheredi]

Just for reference, Tables also does paging through headers, slightly different though, since they give you 2 continuation tokens https://docs.microsoft.com/en-us/rest/api/storageservices/query-entities#response-headers