Fix #974 RPC error when function has single OUT param

test/Feature/RpcSpec.hs

@@ -257,6 +257,25 @@ spec =
       get "/rpc/test" `shouldRespondWith`
         [json|[{"test":"hello","value":1}]|] { matchHeaders = [matchContentTypeJson] }
 
+    context "procs with OUT/INOUT params" $ do
+      it "returns a scalar result when there is a single OUT param" $ do
+        get "/rpc/single_out_param?num=5" `shouldRespondWith`
+          [json|6|] { matchHeaders = [matchContentTypeJson] }
+        get "/rpc/single_json_out_param?a=1&b=two" `shouldRespondWith`
+          [json|{"a": 1, "b": "two"}|] { matchHeaders = [matchContentTypeJson] }
+
+      it "returns a scalar result when there is a single INOUT param" $
+        get "/rpc/single_inout_param?num=2" `shouldRespondWith`
+          [json|3|] { matchHeaders = [matchContentTypeJson] }
+
+      it "returns a row result when there are many OUT params" $
+        get "/rpc/many_out_params" `shouldRespondWith`
+          [json|[{"my_json":{"a": 1, "b": "two"},"num":3,"str":"four"}]|] { matchHeaders = [matchContentTypeJson] }
+
+      it "returns a row result when there are many INOUT params" $
+        get "/rpc/many_inout_params?num=1&str=two" `shouldRespondWith`
+          [json| [{"num":1,"str":"two","b":true}]|] { matchHeaders = [matchContentTypeJson] }
+
     context "only for POST rpc" $ do
       context "expects a single json object" $ do
         it "does not expand posted json into parameters" $

test/fixtures/schema.sql

@@ -1273,10 +1273,22 @@ create table test.being_part (
   part int not null references test.part(part)
 );
 
+create function test.single_out_param(num int, OUT num_plus_one int) AS $$
+  select num + 1;
+$$ language sql;
+
+create function test.single_json_out_param(a int, b text, OUT my_json pg_catalog.json) AS $$
+  select json_build_object('a', a, 'b', b);
+$$ language sql;
+
 create function test.many_out_params(OUT my_json pg_catalog.json, OUT num int, OUT str text) AS $$
   select '{"a": 1, "b": "two"}'::json, 3, 'four'::text;
 $$ language sql;
 
+create function test.single_inout_param(INOUT num int) AS $$
+  select num + 1;
+$$ language sql;
+
 create function test.many_inout_params(INOUT num int, INOUT str text, INOUT b bool DEFAULT true) AS $$
   select num, str, b;
 $$ language sql;