fix: nested empty embeds no longer return empty values and are correc…

…tly omitted

CHANGELOG.md

@@ -9,6 +9,10 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
  - #3558, Add the `admin-server-host` config to set the host for the admin server - @develop7
 
+### Fixed
+
+ - #3093, Nested empty embeds no longer show empty values and are correctly omitted - @laurenceisla 
+
 ### Changed
 
  - #2052, Dropped support for PostgreSQL 9.6 - @wolfgangwalther

src/PostgREST/Plan.hs

@@ -622,7 +622,11 @@ generateRelSelectField (Node ReadPlan{relToParent=Just rel, select, relName, rel
  where
  rsSelName = fromMaybe relName relAlias
  rsEmbedMode = if relIsToOne rel then JsonObject else JsonArray
- rsEmptyEmbed = null select && null forest
+ rsEmptyEmbed = hasOnlyNullEmbed (null select) forest
+ hasOnlyNullEmbed = foldr checkIfNullEmbed
+ checkIfNullEmbed :: ReadPlanTree -> Bool -> Bool
+ checkIfNullEmbed (Node ReadPlan{select=s} f) isNullEmbed =
+ isNullEmbed && hasOnlyNullEmbed (null s) f
 generateRelSelectField _ = Nothing
 
 generateSpreadSelectFields :: ReadPlan -> [SpreadSelectField]

test/spec/Feature/Query/QuerySpec.hs

@@ -1207,6 +1207,20 @@ spec = do
  [json|[{"id":1,"name":"Angela Martin"}]|]
  { matchHeaders = [matchContentTypeJson] }
 
+ it "works on nested relationships" $ do
+ get "/users?select=*,users_tasks(tasks(projects()))" `shouldRespondWith`
+ [json| [{"id":1,"name":"Angela Martin"}, {"id":2,"name":"Michael Scott"}, {"id":3,"name":"Dwight Schrute"}]|]
+ { matchHeaders = [matchContentTypeJson] }
+ get "/users?select=*,users_tasks!inner(tasks!inner(projects()))&users_tasks.tasks.id=eq.3" `shouldRespondWith`
+ [json| [{"id":1,"name":"Angela Martin"}]|]
+ { matchHeaders = [matchContentTypeJson] }
+ get "/users?select=*,tasks(projects(clients()),users_tasks())" `shouldRespondWith`
+ [json| [{"id":1,"name":"Angela Martin"}, {"id":2,"name":"Michael Scott"}, {"id":3,"name":"Dwight Schrute"}]|]
+ { matchHeaders = [matchContentTypeJson] }
+ get "/users?select=*,tasks!inner(projects(clients()),users_tasks(),name)&tasks.id=eq.3" `shouldRespondWith`
+ [json| [{"id":1,"name":"Angela Martin","tasks":[{"name": "Design w10"}]}]|]
+ { matchHeaders = [matchContentTypeJson] }
+
  context "empty root select" $
  it "gives all columns" $ do
  get "/projects?select=" `shouldRespondWith`
@@ -1394,4 +1408,3 @@ spec = do
  get "/infinite_recursion?select=*" `shouldRespondWith`
  [json|{"code":"42P17","message":"infinite recursion detected in rules for relation \"infinite_recursion\"","details":null,"hint":null}|]
  { matchStatus = 500 }
-