Support #exists?

[Fryguy]

No description provided.

[kbrock]

were you thinking exists would be supported by query_relation or the implementer of search?

[Fryguy]

I was thinking query_relation and also in the the querable mixin.

[Fryguy]

Thinking about it more though, I never considered search, but it could be a new mode. Would allow the search writer to write a more efficient exists method if they want it. For example, against a REST API, maybe they want to send a HEAD request.

[kbrock]

The implementer implements first and last. Their implementation is much more optimized than all.first. But maybe exist? isn't that different from first

Don't think there is a simple way for the implementer to register which methods are available from this library. Since this is already so magical, the bran has very little room left for learning the programming interface.

[Fryguy]

Yeah I was originally thinking that exists? could be naively implemented as !!first or limit(1).any? or something. But that precludes the search writer from doing anything more efficient.