Reserve 'distinct' query parameter

For PostgREST#915

CHANGELOG.md

@@ -18,6 +18,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - #877, Base64 secret read from a file ending with a newline - @eric-brechemier
 - #896, Boolean env var interpolation in config file - @begriffs
 - #885, OpenAPI repetition reduced by using more definitions- @ldesgoui
+- #915, Reserve 'distinct' query param - @daurnimator
 - #924, Improve relations initialization time - @9too
 - #927, Treat blank pre-request as missing - @begriffs
 

src/PostgREST/ApiRequest.hs

@@ -118,7 +118,7 @@ userApiRequest schema req reqBody
       , iPreferRepresentation = representation
       , iPreferSingleObjectParameter = singleObject
       , iPreferCount = hasPrefer "count=exact"
-      , iFilters = [ (toS k, toS $ fromJust v) | (k,v) <- qParams, isJust v, k /= "select", not (endingIn ["order", "limit", "offset", "and", "or"] k) ]
+      , iFilters = [ (toS k, toS $ fromJust v) | (k,v) <- qParams, isJust v, k /= "select", not (endingIn ["order", "limit", "offset", "and", "or", "distinct"] k) ]
       , iLogic = [(toS k, toS $ fromJust v) | (k,v) <- qParams, isJust v, endingIn ["and", "or"] k ]
       , iSelect = toS $ fromMaybe "*" $ fromMaybe (Just "*") $ lookup "select" qParams
       , iOrder = [(toS k, toS $ fromJust v) | (k,v) <- qParams, isJust v, endingIn ["order"] k ]