refactor: remove SchemaCache from ApiRequest (#2695)

src/PostgREST/Plan/CallPlan.hs

@@ -1,13 +1,18 @@
+{-# LANGUAGE NamedFieldPuns #-}
 module PostgREST.Plan.CallPlan
   ( CallPlan(..)
   , CallParams(..)
+  , jsonRpcParams
   )
 where
 
+import qualified Data.Aeson                        as JSON
 import qualified Data.ByteString.Lazy              as LBS
+import qualified Data.HashMap.Strict               as HM
 import           PostgREST.SchemaCache.Identifiers (FieldName,
                                                     QualifiedIdentifier)
-import           PostgREST.SchemaCache.Proc        (ProcParam (..))
+import           PostgREST.SchemaCache.Proc        (ProcDescription (..),
+                                                    ProcParam (..))
 
 import Protolude
 
@@ -23,3 +28,29 @@ data CallPlan = FunctionCall
 data CallParams
   = KeyParams [ProcParam] -- ^ Call with key params: func(a := val1, b:= val2)
   | OnePosParam ProcParam -- ^ Call with positional params(only one supported): func(val)
+
+-- | Convert rpc params `/rpc/func?a=val1&b=val2` to json `{"a": "val1", "b": "val2"}
+jsonRpcParams :: ProcDescription -> [(Text, Text)] -> LBS.ByteString
+jsonRpcParams proc prms =
+  if not $ pdHasVariadic proc then -- if proc has no variadic param, save steps and directly convert to json
+    JSON.encode $ HM.fromList $ second JSON.toJSON <$> prms
+  else
+    let paramsMap = HM.fromListWith mergeParams $ toRpcParamValue proc <$> prms in
+    JSON.encode paramsMap
+  where
+    mergeParams :: RpcParamValue -> RpcParamValue -> RpcParamValue
+    mergeParams (Variadic a) (Variadic b) = Variadic $ b ++ a
+    mergeParams v _                       = v -- repeated params for non-variadic parameters are not merged
+
+toRpcParamValue :: ProcDescription -> (Text, Text) -> (Text, RpcParamValue)
+toRpcParamValue proc (k, v) | prmIsVariadic k = (k, Variadic [v])
+                            | otherwise       = (k, Fixed v)
+  where
+    prmIsVariadic prm = isJust $ find (\ProcParam{ppName, ppVar} -> ppName == prm && ppVar) $ pdParams proc
+
+-- | RPC query param value `/rpc/func?v=<value>`, used for VARIADIC functions on form-urlencoded POST and GETs
+-- | It can be fixed `?v=1` or repeated `?v=1&v=2&v=3.
+data RpcParamValue = Fixed Text | Variadic [Text]
+instance JSON.ToJSON RpcParamValue where
+  toJSON (Fixed    v) = JSON.toJSON v
+  toJSON (Variadic v) = JSON.toJSON v