From 6b04491e0441c1e8dae079ef5fc91e5010858fad Mon Sep 17 00:00:00 2001
From: steve-chavez <stevechavezast@gmail.com>
Date: Sat, 17 Apr 2021 15:28:44 -0500
Subject: [PATCH] Filter private junctions and private FK on columns

---
 src/PostgREST/App.hs         |  2 +-
 src/PostgREST/DbStructure.hs | 31 ++++++++++++++++++++-----------
 2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/src/PostgREST/App.hs b/src/PostgREST/App.hs
index 858fda1531..fc784189bf 100644
--- a/src/PostgREST/App.hs
+++ b/src/PostgREST/App.hs
@@ -518,7 +518,7 @@ readRequest :: Monad m => QualifiedIdentifier -> RequestContext -> Handler m Rea
 readRequest QualifiedIdentifier{..} (RequestContext AppConfig{..} dbStructure apiRequest _) =
   liftEither $
     ReqBuilder.readRequest qiSchema qiName configDbMaxRows
-      (dbRelations dbStructure)
+      (dbRelationships dbStructure)
       apiRequest
 
 contentTypeHeaders :: RequestContext -> [HTTP.Header]
diff --git a/src/PostgREST/DbStructure.hs b/src/PostgREST/DbStructure.hs
index cb3f6fe99a..a82978543c 100644
--- a/src/PostgREST/DbStructure.hs
+++ b/src/PostgREST/DbStructure.hs
@@ -64,12 +64,12 @@ import Protolude.Unsafe (unsafeHead)
 
 
 data DbStructure = DbStructure
-  { dbTables      :: [Table]
-  , dbColumns     :: [Column]
-  , dbRelations   :: [Relation]
-  , dbPrimaryKeys :: [PrimaryKey]
-  , dbProcs       :: ProcsMap
-  , pgVersion     :: PgVersion
+  { dbTables        :: [Table]
+  , dbColumns       :: [Column]
+  , dbRelationships :: [Relation]
+  , dbPrimaryKeys   :: [PrimaryKey]
+  , dbProcs         :: ProcsMap
+  , pgVersion       :: PgVersion
   }
   deriving (Generic, JSON.ToJSON)
 
@@ -85,14 +85,23 @@ tablePKCols dbs tSchema tName =  pkName <$> filter (\pk -> tSchema == (tableSche
 removeInternalSchemas :: DbStructure -> [Schema] -> DbStructure
 removeInternalSchemas dbStruct schemas =
   DbStructure {
-      dbTables      = filter (\x -> tableSchema x `elem` schemas) $ dbTables dbStruct
-    , dbColumns     = filter (\x -> tableSchema (colTable x) `elem` schemas) $ dbColumns dbStruct
-    , dbRelations   = filter (\x -> tableSchema (relTable x) `elem` schemas &&
-                                    tableSchema (relFTable x) `elem` schemas) $ dbRelations dbStruct
+      dbTables        = filter (\x -> tableSchema x `elem` schemas) $ dbTables dbStruct
+    , dbColumns       = removeInternalFK <$> filter (\x -> tableSchema (colTable x) `elem` schemas) (dbColumns dbStruct)
+    , dbRelationships = filter (\x -> tableSchema (relTable x) `elem` schemas &&
+                                    tableSchema (relForeignTable x) `elem` schemas &&
+                                    hasInternalJunction x) $ dbRelationships dbStruct
     , dbPrimaryKeys = filter (\x -> tableSchema (pkTable x) `elem` schemas) $ dbPrimaryKeys dbStruct
     , dbProcs       = M.filterWithKey (\(QualifiedIdentifier sch _) _ -> sch `elem` schemas) $ dbProcs dbStruct
     , pgVersion     = pgVersion dbStruct
     }
+  where
+    removeInternalFK col = case colFK col of
+      Just fk | tableSchema (colTable $ fkCol fk) `notElem` schemas -> col{colFK = Nothing}
+              | otherwise                                           -> col
+      Nothing -> col
+    hasInternalJunction rel = case relCardinality rel of
+      M2M Junction{junTable} -> tableSchema junTable `elem` schemas
+      _                      -> False
 
 -- | The source table column a view column refers to
 type SourceColumn = (Column, ViewColumn)
@@ -118,7 +127,7 @@ getDbStructure schemas extraSearchPath pgVer prepared = do
   return DbStructure {
       dbTables = tabs
     , dbColumns = cols'
-    , dbRelations = rels
+    , dbRelationships = rels
     , dbPrimaryKeys = keys'
     , dbProcs = procs
     , pgVersion = pgVer