Prevent duplicate call to stored procs

Reuse a CTE for results of call

CHANGELOG.md

@@ -6,6 +6,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ## Unreleased
 
 ### Fixed
+- Prevent duplicate call to stored procs (regression) - @begriffs
 - Allow SQL functions to generate registered JWT claims - @begriffs
 - Terminate gracefully on SIGTERM (for use in Docker) - @recmo
 - Relation detection fix for views that depend on multiple tables - @ruslantalpa

src/PostgREST/QueryBuilder.hs

@@ -208,18 +208,22 @@ callProc :: QualifiedIdentifier -> JSON.Object -> NonnegRange -> Bool -> H.Query
 callProc qi params range countTotal =
   H.statement sql HE.unit decodeProc True
   where
-    sql = [qc| SELECT
+    sql = [qc|
-              {countQuery} as countTotal,
+            WITH t AS (select * {_callSql})
-              {countResult} as countResult,
+            SELECT
+              {_countExpr} as countTotal,
+              pg_catalog.count(1) as countResult,
               array_to_json(
-                coalesce(array_agg(row_to_json(t)), '\{}')
+                coalesce(array_agg(row_to_json(r)), '\{}')
               )::character varying
-              from (select * {_callSql} {limitF range}) t |]
+            FROM (select * from t {limitF range}) r;
+          |]
     _args = intercalate "," $ map _assignment (HM.toList params)
     _assignment (n,v) = pgFmtIdent n <> ":=" <> insertableValue v
     _callSql = [qc| from {fromQi qi}({_args}) |] :: BS.ByteString
-    countQuery = if countTotal then [qc| (select pg_catalog.count(1) {_callSql} c) |] else "null::bigint" :: BS.ByteString
+    _countExpr = if countTotal
-    countResult = "pg_catalog.count(t)" :: BS.ByteString
+                   then "(select pg_catalog.count(1) from t)"
+                   else "null::bigint" :: BS.ByteString
     decodeProc = HD.maybeRow procRow
     procRow = (,,) <$> HD.nullableValue HD.int8 <*> HD.value HD.int8
                    <*> HD.value HD.json

test/Feature/QuerySpec.hs

@@ -422,6 +422,12 @@ spec = do
       it "GET with 405 on known procs" $
         get "/rpc/sayhello" `shouldRespondWith` 405
 
+    it "executes the proc exactly once per request" $ do
+      post "/rpc/callcounter" [json| {} |] `shouldRespondWith`
+        [json| [{"callcounter":1}] |]
+      post "/rpc/callcounter" [json| {} |] `shouldRespondWith`
+        [json| [{"callcounter":2}] |]
+
   describe "weird requests" $ do
     it "can query as normal" $ do
       get "/Escap3e;" `shouldRespondWith`

test/fixtures/privileges.sql

@@ -43,6 +43,7 @@ GRANT INSERT ON TABLE insertonly TO postgrest_test_anonymous;
 GRANT USAGE ON SEQUENCE
       auto_incrementing_pk_id_seq
     , items_id_seq
+    , callcounter_count
 TO postgrest_test_anonymous;
 
 -- Privileges for non anonymous users

test/fixtures/schema.sql

@@ -261,6 +261,18 @@ CREATE FUNCTION sayhello(name text) RETURNS text
 $_$;
 
 
+--
+-- Name: callcounter(); Type: FUNCTION; Schema: test; Owner: -
+--
+
+CREATE SEQUENCE callcounter_count START 1;
+
+CREATE FUNCTION callcounter() RETURNS bigint
+    LANGUAGE sql
+    AS $_$
+    SELECT nextval('test.callcounter_count');
+$_$;
+
 --
 -- Name: test_empty_rowset(); Type: FUNCTION; Schema: test; Owner: -
 --