Pagination header Content-Range / Range-Unit is not working

[rv2931]

Environment

• PostgreSQL version: Dokcer Postgres:10
• PostgREST version: postgrest/postgrest:v12.2.3
• Operating system: Windows/Podman

Description of issue

According to the documentation, it is possible to manage pagination with header following parameters:

• Range-Unit: items
• Content-Range: 0-14/*

Unfortunetly I'm trying to paginate with these parameters but the response contains all items and not only the 15th first

I've triued using query parameters limit & offset and these query parameters are working well

• How you make the request to PostgREST (curl command preferred).
• Here you have the curl command I use to test, I'm using postman with the same result
  curl -H 'Content-Range: 0-14/*' -H 'Range-Unit: items' http://localhost:3000/my_table_items
  this returns a non paginated answer with Content-Range: 0-394/395
• The PostgREST response.
  IS 200 OK but contains all items present in the my_table_items table

[wolfgangwalther]

Hm. The section you are referring to is this, I guess: https://docs.postgrest.org/en/v12/references/api/pagination_count.html#limits-and-pagination

This mentions explicitly that this the response format. You can expect the Content-Range header as a return. (This is the same with all Content-XX headers btw, you never send them in a request)

Further down, you can find the first mention of how to request that: https://docs.postgrest.org/en/v12/references/api/pagination_count.html#range-header

The header you need to send is Range.

[wolfgangwalther]

I took a look to the HTTP standard and according to what I've found, the syntax of Range doesn't match the standard

Can you cite that RFC exactly and where you think this is wrong?

"At first glance", I see the Range-Unit header defined in the RFC. So surely that seems to be OK?

[laurenceisla]

Can you cite that RFC exactly and where you think this is wrong?

Ah, it's mentioned in RFC 7233, we are tracking the issue in #1089. It's confirmed by Roy Fielding there: #1089 (comment)

[rv2931]

Yeah sure. Sorry I thought I joined the link
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Range

Range: <unit>=<range-start>-
Range: <unit>=<range-start>-<range-end>
Range: <unit>=<range-start>-<range-end>, <range-start>-<range-end>, …
Range: <unit>=-<suffix-length>

[rv2931]

I found the same in officiel RFC 9110
https://www.rfc-editor.org/rfc/rfc9110.html#field.range
Range = ranges-specifier
https://www.rfc-editor.org/rfc/rfc9110.html#rule.ranges-specifier

  ranges-specifier = range-unit "=" range-set
  range-set        = 1#range-spec
  range-spec       = int-range
                   / suffix-range
                   / other-range

[wolfgangwalther]

Interesting. I read the "range-unit" part when I looked for the header and was too quick to note the difference between:

range-unit = ... ... and Range-Unit = .... The former exists, the latter doesn't.

I.e. the way this is written, it's just a definition of what range-unit means and not a new header definition. Those are capitalized.

[jmealo]

@wolfgangwalther: TIL: It looks like the latest RFC / HTTP Semantics spec has some valid use cases for Content-Range in PUT request headers (provided there is a request body). It's apparently valid for a partial PUT to specify the ranges being provided in the body. This doesn't apply here, but it's interesting none-the-less.
https://www.rfc-editor.org/rfc/rfc9110.html#section-14.5

[wolfgangwalther]

Right, I wasn't precise enough: Content-XXX headers are always about the body that you are sending. So when you are making a request, you can say Content-Type to describe the mime type of the body you are sending. The server will do the same. The same applies to Content-Range.