feat: custom SQL handler for the "*/*" media type

src/PostgREST/Plan.hs

@@ -62,6 +62,7 @@ import PostgREST.SchemaCache.Relationship    (Cardinality (..),
 import PostgREST.SchemaCache.Representations (DataRepresentation (..),
                                               RepresentationsMap)
 import PostgREST.SchemaCache.Routine         (MediaHandler (..),
+                                              MediaHandlerMap,
                                               Routine (..),
                                               RoutineMap,
                                               RoutineParam (..),
@@ -991,10 +992,9 @@ addFilterToLogicForest :: CoercibleFilter -> [CoercibleLogicTree] -> [CoercibleL
 addFilterToLogicForest flt lf = CoercibleStmnt flt : lf
 
 -- | Do content negotiation. i.e. choose a media type based on the intersection of accepted/produced media types.
-negotiateContent :: AppConfig -> ApiRequest -> QualifiedIdentifier -> [MediaType] ->
+negotiateContent :: AppConfig -> ApiRequest -> QualifiedIdentifier -> [MediaType] -> MediaHandlerMap -> Either ApiRequestError (MediaHandler, MediaType)
-                    HM.HashMap (RelIdentifier, MediaType) MediaHandler -> Either ApiRequestError (MediaHandler, MediaType)
 negotiateContent conf ApiRequest{iAction=act, iPreferences=Preferences{preferRepresentation=rep}} identifier accepts produces =
-  mtAnyToJSON $ case (act, firstAcceptedPick) of
+  defaultMTAnyToMTJSON $ case (act, firstAcceptedPick) of
     (_, Nothing)                         -> Left . MediaTypeError $ map MediaType.toMime accepts
     (ActionMutate _, Just (x, mt))       -> Right (if rep == Just Full then x else NoAgg, mt)
     -- no need for an aggregate on HEAD https://github.com/PostgREST/postgrest/issues/2849
@@ -1003,21 +1003,23 @@ negotiateContent conf ApiRequest{iAction=act, iPreferences=Preferences{preferRep
     (ActionInvoke InvHead, Just (_, mt)) -> Right (NoAgg, mt)
     (_, Just (x, mt))                    -> Right (x, mt)
   where
-    -- TODO initial */* is not overridable
+    -- the initial handler in the schema cache has a */* to BuiltinAggJson but it doesn't preserve the media type (application/json)
-    -- initial handlers in the schema cache have a */* to BuiltinAggJson but they don't preserve the media type (application/json)
+    -- we just convert the default */* to application/json here
-    -- for now we just convert the resultant */* to application/json here
+    -- TODO resolving to "application/json" for "*/*" is not correct when using a "*/*" custom handler media type.
-    mtAnyToJSON = mapRight (\(x, y) -> (x, if y == MTAny then MTApplicationJSON else y))
+    -- We should return "application/octet-stream" as the generic type instead.
-    -- if there are multiple accepted media types, pick the first
+    defaultMTAnyToMTJSON = mapRight (\(x, y) -> (x, if y == MTAny then MTApplicationJSON else y))
-    firstAcceptedPick = listToMaybe $ mapMaybe searchMT accepts
+    firstAcceptedPick = listToMaybe $ mapMaybe matchMT accepts -- If there are multiple accepted media types, pick the first. This is usual in content negotiation.
-    lookupIdent mt = -- first search for an aggregate that applies to the particular relation, then for one that applies to anyelement
+    matchMT mt = case mt of
-      HM.lookup (RelId identifier, mt) produces <|> HM.lookup (RelAnyElement, mt) produces
-    searchMT mt = case mt of
       -- all the vendored media types have special handling as they have media type parameters, they cannot be overridden
       m@(MTVndSingularJSON strip)                 -> Just (BuiltinAggSingleJson strip, m)
       m@MTVndArrayJSONStrip                       -> Just (BuiltinAggArrayJsonStrip, m)
       m@(MTVndPlan (MTVndSingularJSON strip) _ _) -> mtPlanToNothing $ Just (BuiltinAggSingleJson strip, m)
       m@(MTVndPlan MTVndArrayJSONStrip _ _)       -> mtPlanToNothing $ Just (BuiltinAggArrayJsonStrip, m)
       -- all the other media types can be overridden
-      m@(MTVndPlan mType _ _)                     -> mtPlanToNothing $ (,) <$> lookupIdent mType <*> pure m
+      m@(MTVndPlan mType _ _)                     -> mtPlanToNothing $ (,) <$> lookupHandler mType <*> pure m
-      x                                           -> (,) <$> lookupIdent x <*> pure x
+      x                                           -> (,) <$> lookupHandler x <*> pure x
     mtPlanToNothing x = if configDbPlanEnabled conf then x else Nothing -- don't find anything if the plan media type is not allowed
+    lookupHandler mt =
+      HM.lookup (RelId identifier, MTAny) produces <|> -- lookup handler that applies to `*/*` and identifier
+      HM.lookup (RelId identifier, mt) produces <|>    -- lookup handler that applies to a particular media type and identifier
+      HM.lookup (RelAnyElement, mt) produces           -- lookup handler that applies to a particular media type and anyelement

src/PostgREST/SchemaCache.hs

@@ -1147,7 +1147,7 @@ mediaHandlers pgVer =
           JOIN pg_type b ON t.typbasetype = b.oid
           WHERE
             t.typbasetype <> 0 and
-            t.typname ~* '^[A-Za-z0-9.-]+/[A-Za-z0-9.\+-]+$'
+            (t.typname ~* '^[A-Za-z0-9.-]+/[A-Za-z0-9.\+-]+$' or t.typname = '*/*')
       )
       select
         proc_schema.nspname           as handler_schema,

test/spec/Feature/Query/CustomMediaSpec.hs

@@ -222,3 +222,81 @@ spec = describe "custom media types" $ do
         simpleBody r `shouldBe` readFixtureFile "lines.csv"
         simpleHeaders r `shouldContain` [("Content-Type", "text/csv; charset=utf-8")]
         simpleHeaders r `shouldContain` [("Content-Disposition", "attachment; filename=\"lines.csv\"")]
+
+  context "any media type" $ do
+    context "on functions" $ do
+      -- TODO not correct, it should return the generic "application/octet-stream"
+      it "returns application/json for */* if not explicitly set" $ do
+        request methodGet "/rpc/ret_any_mt" (acceptHdrs "*/*") ""
+          `shouldRespondWith` "any"
+          { matchStatus  = 200
+          , matchHeaders = [matchContentTypeJson]
+          }
+
+      it "accepts any media type and sets it as a header" $ do
+        request methodGet "/rpc/ret_any_mt" (acceptHdrs "app/bingo") ""
+          `shouldRespondWith` "any"
+          { matchStatus  = 200
+          , matchHeaders = ["Content-Type" <:> "app/bingo"]
+          }
+
+        request methodGet "/rpc/ret_any_mt" (acceptHdrs "text/bango") ""
+          `shouldRespondWith` "any"
+          { matchStatus  = 200
+          , matchHeaders = ["Content-Type" <:> "text/bango"]
+          }
+
+        request methodGet "/rpc/ret_any_mt" (acceptHdrs "image/boingo") ""
+          `shouldRespondWith` "any"
+          { matchStatus  = 200
+          , matchHeaders = ["Content-Type" <:> "image/boingo"]
+          }
+
+      it "returns custom media type for */* if explicitly set" $ do
+        request methodGet "/rpc/ret_some_mt" (acceptHdrs "*/*") ""
+          `shouldRespondWith` "groucho"
+          { matchStatus  = 200
+          , matchHeaders = ["Content-Type" <:> "app/groucho"]
+          }
+
+      it "accepts some media types if there's conditional logic" $ do
+        request methodGet "/rpc/ret_some_mt" (acceptHdrs "app/chico") ""
+          `shouldRespondWith` "chico"
+          { matchStatus  = 200
+          , matchHeaders = ["Content-Type" <:> "app/chico"]
+          }
+
+        request methodGet "/rpc/ret_some_mt" (acceptHdrs "app/harpo") ""
+          `shouldRespondWith` "harpo"
+          { matchStatus  = 200
+          , matchHeaders = ["Content-Type" <:> "app/harpo"]
+          }
+
+        request methodGet "/rpc/ret_some_mt" (acceptHdrs "text/csv") ""
+          `shouldRespondWith` 415
+
+    context "on tables" $ do
+      -- TODO not correct, it should return the generic "application/octet-stream"
+      it "returns application/json for */* if not explicitly set" $ do
+        request methodGet "/some_numbers?val=eq.1" (acceptHdrs "*/*") ""
+          `shouldRespondWith` "anything\n1"
+          { matchStatus  = 200
+          , matchHeaders = [matchContentTypeJson]
+          }
+
+      it "accepts any media type and sets it as a header" $ do
+        request methodGet "/some_numbers?val=eq.2" (acceptHdrs "magic/number") ""
+          `shouldRespondWith` "magic\n2"
+          { matchStatus  = 200
+          , matchHeaders = ["Content-Type" <:> "magic/number"]
+          }
+        request methodGet "/some_numbers?val=eq.3" (acceptHdrs "crazy/bingo") ""
+          `shouldRespondWith` "crazy\n3"
+          { matchStatus  = 200
+          , matchHeaders = ["Content-Type" <:> "crazy/bingo"]
+          }
+        request methodGet "/some_numbers?val=eq.4" (acceptHdrs "unknown/unknown") ""
+          `shouldRespondWith` "anything\n4"
+          { matchStatus  = 200
+          , matchHeaders = ["Content-Type" <:> "unknown/unknown"]
+          }

test/spec/fixtures/schema.sql

@@ -130,6 +130,7 @@ create domain "application/json" as json;
 create domain "application/vnd.pgrst.object" as json;
 create domain "text/tab-separated-values" as text;
 create domain "text/csv" as text;
+create domain "*/*" as bytea;
 
 CREATE TABLE items (
     id bigserial primary key
@@ -3593,7 +3594,6 @@ $$ language sql;
 
 create or replace function test.tsv_final (data "text/tab-separated-values")
 returns "text/tab-separated-values" as $$
-  select set_config('response.headers', '[{"Cache-Control": "public"}, {"Cache-Control": "max-age=259200"}]', true);
   select (E'id\tname\tclient_id\n' || data)::"text/tab-separated-values";
 $$ language sql;
 
@@ -3650,3 +3650,58 @@ create table budget_expenses (
 , expense_amount numeric
 , budget_category_id integer references budget_categories(id)
 );
+
+create or replace function ret_any_mt ()
+returns "*/*" as $$
+  select 'any'::"*/*";
+$$ language sql;
+
+create or replace function ret_some_mt ()
+returns "*/*" as $$
+declare
+  req_accept text := current_setting('request.headers', true)::json->>'accept';
+  resp bytea;
+begin
+  case req_accept
+    when 'app/chico'   then resp := 'chico';
+    when 'app/harpo'   then resp := 'harpo';
+    when '*/*'         then
+      perform set_config('response.headers', '[{"Content-Type": "app/groucho"}]', true);
+      resp := 'groucho';
+    else
+      raise sqlstate 'PT415' using message = 'Unsupported Media Type';
+  end case;
+  return resp;
+end; $$ language plpgsql;
+
+create table some_numbers as select x::int as val from generate_series(1,10) x;
+
+create or replace function some_trans (state "*/*", next some_numbers)
+returns "*/*" as $$
+  select (state || E'\n' || next.val::text::bytea)::"*/*";
+$$ language sql;
+
+create or replace function some_final (data "*/*")
+returns "*/*" as $$
+declare
+  req_accept text := current_setting('request.headers', true)::json->>'accept';
+  prefix bytea;
+begin
+  case req_accept
+    when 'magic/number' then
+      prefix := 'magic';
+    when 'crazy/bingo'  then
+      prefix := 'crazy';
+    else
+      prefix := 'anything';
+  end case;
+  return (prefix || data)::"*/*";
+end; $$ language plpgsql;
+
+drop aggregate if exists some_agg (some_numbers);
+create aggregate test.some_agg (some_numbers) (
+  initcond = ''
+, stype = "*/*"
+, sfunc = some_trans
+, finalfunc = some_final
+);