nightly: Requests no longer return single-element array by default for single object return functions

[W1M0R]

Environment

• PostgreSQL version: 12.6
• PostgREST version: nightly-2021-03-05-19-03-d3a8b5f
• Operating system: Ubuntu

Description of issue

Consider the following function, that gets exposed as /rpc/login:

create or replace function public.login(options my_types.login_options) returns my_types.login_result as

In 7.0.1, this function would return a JSON array with a single element, and clients had to opt-in using 'Accept: application/vnd.pgrst.object+json'. Using nightly-2021-03-05-19-03-d3a8b5f, this function now returns a single object, that is, not a JSON array. I can't seem to opt-out of that. Although returning a single object makes more sense, unfortunately clients of the API already expect a single element JSON array, so an upgrade to the next PostgREST version would be a breaking change for clients.

Consider whether it may be helpful to enable/disable that functionality via the postgrest.conf file, or via some other method (perhaps on a per-function basis, e.g. it would be great to disable the new functionality for stable endpoints such as /v1/login, but use the new default for newly added endpoints).

#1779

[wolfgangwalther]

Yes, that's on purpose. It will be listed as a breaking change for the next release. I don't think we'll provide a way to opt out of that.

If you don't want to change your clients for now, you can just mark your function's return type as returns setof my_types.login_result - but still only return one row. This will give you the same one-element-array - in both the current and the next release.

[W1M0R]

Thank you very much for the workaround @wolfgangwalther, that should solve my issue.