From f9f572a5d2e16d7baa77bca508b8b4ad0f71d417 Mon Sep 17 00:00:00 2001
From: Wolfgang Walther <walther@technowledgy.de>
Date: Thu, 27 Oct 2022 16:31:49 +0200
Subject: [PATCH] fix: Treat non-setof computed relationships as M2O/O2M

Fixes #2481

Signed-off-by: Wolfgang Walther <walther@technowledgy.de>
---
 CHANGELOG.md                                |  1 +
 src/PostgREST/SchemaCache.hs                | 12 ++++----
 test/spec/Feature/Query/ComputedRelsSpec.hs | 32 +++++++++++++++++----
 test/spec/fixtures/schema.sql               |  4 +++
 4 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 08fa9b0c1..9b8264169 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
  - #2356, Fix a regression in openapi output with mode follow-privileges - @wolfgangwalther
  - #2283, Fix infinite recursion when loading schema cache with self-referencing view - @wolfgangwalther
  - #2343, Return status code 200 for PATCH requests which don't affect any rows - @wolfgangwalther
+ - #2481, Treat computed relationships not marked SETOF as M2O/O2O relationship - @wolfgangwalther
 
 ### Changed
 
diff --git a/src/PostgREST/SchemaCache.hs b/src/PostgREST/SchemaCache.hs
index 84ef9c9c0..534659b54 100644
--- a/src/PostgREST/SchemaCache.hs
+++ b/src/PostgREST/SchemaCache.hs
@@ -727,12 +727,12 @@ allComputedRels =
     computed_rels as (
       select
         (parse_ident(p.pronamespace::regnamespace::text))[1] as schema,
-        p.proname::text          as name,
-        arg_schema.nspname::text as rel_table_schema,
-        arg_name.typname::text   as rel_table_name,
-        ret_schema.nspname::text as rel_ftable_schema,
-        ret_name.typname::text   as rel_ftable_name,
-        p.prorows = 1            as single_row
+        p.proname::text                  as name,
+        arg_schema.nspname::text         as rel_table_schema,
+        arg_name.typname::text           as rel_table_name,
+        ret_schema.nspname::text         as rel_ftable_schema,
+        ret_name.typname::text           as rel_ftable_name,
+        not p.proretset or p.prorows = 1 as single_row
       from pg_proc p
         join pg_type      arg_name   on arg_name.oid = p.proargtypes[0]
         join pg_namespace arg_schema on arg_schema.oid = arg_name.typnamespace
diff --git a/test/spec/Feature/Query/ComputedRelsSpec.hs b/test/spec/Feature/Query/ComputedRelsSpec.hs
index d3430efc9..612453d09 100644
--- a/test/spec/Feature/Query/ComputedRelsSpec.hs
+++ b/test/spec/Feature/Query/ComputedRelsSpec.hs
@@ -12,14 +12,24 @@ import SpecHelper
 
 spec :: SpecWith ((), Application)
 spec = describe "computed relationships" $ do
-  it "can define a many-to-one relationship and embed" $
-    get "/videogames?select=name,designers:computed_designers(name)"
+  it "can define a many-to-one relationship with SETOF and ROWS 1 and embed" $
+    get "/videogames?select=name,designer:computed_designers(name)"
     `shouldRespondWith`
       [json|[
-        {"name":"Civilization I","designers":{"name":"Sid Meier"}},
-        {"name":"Civilization II","designers":{"name":"Sid Meier"}},
-        {"name":"Final Fantasy I","designers":{"name":"Hironobu Sakaguchi"}},
-        {"name":"Final Fantasy II","designers":{"name":"Hironobu Sakaguchi"}}
+        {"name":"Civilization I","designer":{"name":"Sid Meier"}},
+        {"name":"Civilization II","designer":{"name":"Sid Meier"}},
+        {"name":"Final Fantasy I","designer":{"name":"Hironobu Sakaguchi"}},
+        {"name":"Final Fantasy II","designer":{"name":"Hironobu Sakaguchi"}}
+      ]|] { matchHeaders = [matchContentTypeJson] }
+
+  it "can define a many-to-one relationship without SETOF and embed" $
+    get "/videogames?select=name,designer:computed_designers_noset(name)"
+    `shouldRespondWith`
+      [json|[
+        {"name":"Civilization I","designer":{"name":"Sid Meier"}},
+        {"name":"Civilization II","designer":{"name":"Sid Meier"}},
+        {"name":"Final Fantasy I","designer":{"name":"Hironobu Sakaguchi"}},
+        {"name":"Final Fantasy II","designer":{"name":"Hironobu Sakaguchi"}}
       ]|] { matchHeaders = [matchContentTypeJson] }
 
   it "can define a one-to-many relationship and embed" $
@@ -48,6 +58,16 @@ spec = describe "computed relationships" $ do
         { matchStatus  = 200
         , matchHeaders = ["Content-Range" <:> "0-1/2"]
         }
+    request methodGet "/videogames?select=name,designer:computed_designers_noset!inner(name)&designer.name=like.*Hironobu*"
+      [("Prefer", "count=exact")] ""
+      `shouldRespondWith`
+        [json|[
+          {"name":"Final Fantasy I","designer":{"name":"Hironobu Sakaguchi"}},
+          {"name":"Final Fantasy II","designer":{"name":"Hironobu Sakaguchi"}}
+        ]|]
+        { matchStatus  = 200
+        , matchHeaders = ["Content-Range" <:> "0-1/2"]
+        }
 
   it "works with rpc" $ do
     get "/rpc/getallvideogames?select=name,designer:computed_designers(name)"
diff --git a/test/spec/fixtures/schema.sql b/test/spec/fixtures/schema.sql
index b830d8168..5cb2e22f9 100644
--- a/test/spec/fixtures/schema.sql
+++ b/test/spec/fixtures/schema.sql
@@ -2737,6 +2737,10 @@ CREATE FUNCTION test.computed_designers(test.videogames) RETURNS SETOF test.desi
   SELECT * FROM test.designers WHERE id = $1.designer_id;
 $$ LANGUAGE sql STABLE ROWS 1;
 
+CREATE FUNCTION test.computed_designers_noset(test.videogames) RETURNS test.designers AS $$
+  SELECT * FROM test.designers WHERE id = $1.designer_id;
+$$ LANGUAGE sql STABLE;
+
 CREATE FUNCTION test.computed_videogames(test.designers) RETURNS SETOF test.videogames AS $$
   SELECT * FROM test.videogames WHERE designer_id = $1.id;
 $$ LANGUAGE sql STABLE;