Add FROM targets aliasing to avoid conflict in embeds

CHANGELOG.md

@@ -14,6 +14,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 - #828, Fix computed column only working in public schema - @steve-chavez
 - #925, Fix RPC high memory usage by using parametrized query and avoiding json encoding - @steve-chavez
+- #987, Fix embedding with self-reference foreign key - @steve-chavez
 
 ### Changed
 

src/PostgREST/DbRequestBuilder.hs

@@ -60,17 +60,21 @@ readRequest maxRows allRels proc apiRequest  =
 
         _ -> Nothing
 
+    -- Build tree with a Level attribute so when an embed occurs and the parent node has the same name as the child we can differentiate them by having
+    -- an alias like "node_lvl", this is related to issue #987.
     buildReadRequest :: [Tree SelectItem] -> ReadRequest
     buildReadRequest fieldTree =
-      let rootNodeName = if action == ActionRead then rootTableName else sourceCTEName in
-      foldr treeEntry (Node (Select [] [rootNodeName] [] [] [] allRange, (rootNodeName, Nothing, Nothing, Nothing)) []) fieldTree
+      let rootLvl = 1
+          rootNodeName = if action == ActionRead then rootTableName else sourceCTEName in
+      foldr (treeEntry rootLvl) (Node (Select [] [rootNodeName] [] [] [] allRange, (rootNodeName, Nothing, Nothing, Nothing, rootLvl)) []) fieldTree
       where
-        treeEntry :: Tree SelectItem -> ReadRequest -> ReadRequest
-        treeEntry (Node fld@((fn, _),_,alias,relationDetail) fldForest) (Node (q, i) rForest) =
+        treeEntry :: Level -> Tree SelectItem -> ReadRequest -> ReadRequest
+        treeEntry lvl (Node fld@((fn, _),_,alias,relationDetail) fldForest) (Node (q, i) rForest) =
+          let nxtLvl = succ lvl in
           case fldForest of
             [] -> Node (q {select=fld:select q}, i) rForest
             _  -> Node (q, i) $
-                  foldr treeEntry (Node (Select [] [fn] [] [] [] allRange, (fn, Nothing, alias, relationDetail)) []) fldForest:rForest
+                  foldr (treeEntry nxtLvl) (Node (Select [] [fn] [] [] [] allRange, (fn, Nothing, alias, relationDetail, nxtLvl)) []) fldForest:rForest
 
     relations :: [Relation]
     relations = case action of
@@ -105,9 +109,9 @@ augumentRequestWithJoin schema allRels request =
   >>= addJoinConditions schema
 
 addRelations :: Schema -> [Relation] -> Maybe ReadRequest -> ReadRequest -> Either ApiRequestError ReadRequest
-addRelations schema allRelations parentNode (Node readNode@(query, (name, _, alias, relationDetail)) forest) =
+addRelations schema allRelations parentNode (Node readNode@(query, (name, _, alias, relationDetail, level)) forest) =
   case parentNode of
-    (Just (Node (Select{from=[parentNodeTable]}, (_, _, _, _)) _)) ->
+    (Just (Node (Select{from=[parentNodeTable]}, _) _)) ->
       Node <$> readNode' <*> forest'
       where
         forest' = updateForest $ hush node'
@@ -190,13 +194,13 @@ addRelations schema allRelations parentNode (Node readNode@(query, (name, _, ali
                   )
                 ) allRelations
               n `colMatches` rc = (toS ("^" <> rc <> "_?(?:|[iI][dD]|[fF][kK])$") :: BS.ByteString) =~ (toS n :: BS.ByteString)
-        addRel :: (ReadQuery, (NodeName, Maybe Relation, Maybe Alias, Maybe RelationDetail)) -> Relation -> (ReadQuery, (NodeName, Maybe Relation, Maybe Alias, Maybe RelationDetail))
-        addRel (query', (n, _, a, _)) r = (query' {from=fromRelation}, (n, Just r, a, Nothing))
+        addRel :: (ReadQuery, (NodeName, Maybe Relation, Maybe Alias, Maybe RelationDetail, Level)) -> Relation -> (ReadQuery, (NodeName, Maybe Relation, Maybe Alias, Maybe RelationDetail, Level))
+        addRel (query', (n, _, a, _, lvl)) r = (query' {from=fromRelation}, (n, Just r, a, Nothing, lvl))
           where fromRelation = map (\t -> if t == n then tableName (relTable r) else t) (from query')
 
     _ -> n' <$> updateForest (Just (n' forest))
       where
-        n' = Node (query, (name, Just r, alias, Nothing))
+        n' = Node (query, (name, Just r, alias, Nothing, level))
         t = Table schema name Nothing True -- !!! TODO find another way to get the table from the query
         r = Relation t [] t [] Root Nothing Nothing Nothing
   where
@@ -204,7 +208,7 @@ addRelations schema allRelations parentNode (Node readNode@(query, (name, _, ali
     updateForest n = mapM (addRelations schema allRelations n) forest
 
 addJoinConditions :: Schema -> ReadRequest -> Either ApiRequestError ReadRequest
-addJoinConditions schema (Node node@(query, nodeProps@(_, relation, _, _)) forest) =
+addJoinConditions schema (Node node@(query, nodeProps@(_, relation, _, _, lvl)) forest) =
   case relation of
     Just Relation{relType=Root} -> Node node  <$> updatedForest -- this is the root node
     Just rel@Relation{relType=Parent} -> Node (augmentQuery rel, nodeProps) <$> updatedForest
@@ -215,23 +219,31 @@ addJoinConditions schema (Node node@(query, nodeProps@(_, relation, _, _)) fores
     _ -> Left UnknownRelation
   where
     updatedForest = mapM (addJoinConditions schema) forest
-    augmentQuery rel = foldr addJoinCondToReadQuery query (getJoinConds rel)
-    addJoinCondToReadQuery jc rq@Select{joinConds=jcs} = rq{joinConds=jc:jcs}::ReadQuery
+    augmentQuery rel = foldr addJoinCondToReadQuery query (getJoinConds lvl rel)
+    addJoinCondToReadQuery jc rq@Select{joinConds=jcs} = rq{joinConds=jc:jcs}
 
-getJoinConds :: Relation -> [JoinCond]
-getJoinConds (Relation t cols ft fcs typ lt lc1 lc2) =
+getJoinConds :: Integer -> Relation -> [JoinCond]
+getJoinConds level (Relation t cols ft fcs typ lt lc1 lc2) =
   case typ of
-    Child  -> zipWith (toJoinCond tN ftN) cols fcs
-    Parent -> zipWith (toJoinCond tN ftN) cols fcs
-    Many   -> zipWith (toJoinCond tN ltN) cols (fromMaybe [] lc1) ++ zipWith (toJoinCond ftN ltN) fcs (fromMaybe [] lc2)
+    -- JoinCond needs the Level attr to know the tables aliases
+    -- The level depends on the sql query structure
+    -- Child has the embed as:
+    -- SELECT .., COALESCE(SELECT .. FROM ch AS ch_lvl_2 WHERE ch_lvl_2.col = p_lvl_1.col) FROM p AS p_lvl_1
+    -- Parent has similar structure regarding the levels
+    -- Many has the embed as:
+    -- SELECT .., COALESCE(SELECT .. FROM ch AS ch_lvl_2, gch AS gch_lvl_2 WHERE ch_lvl_2.col = gch_lvl_2.col AND p_lvl_1.acol = ch_lvl_2.acol)
+    -- FROM p AS p_lvl_1
+    Child  -> zipWith (toJoinCond (tN, level) (ftN, level - 1)) cols fcs
+    Parent -> zipWith (toJoinCond (tN, level) (ftN, level - 1)) cols fcs
+    Many   -> zipWith (toJoinCond (tN, level) (ltN, level)) cols (fromMaybe [] lc1) ++ zipWith (toJoinCond (ftN, level - 1) (ltN, level)) fcs (fromMaybe [] lc2)
     Root   -> undefined
   where
     s = if typ == Parent then "" else tableSchema t
     tN = tableName t
     ftN = tableName ft
     ltN = fromMaybe "" (tableName <$> lt)
-    toJoinCond :: Text -> Text -> Column -> Column -> JoinCond
-    toJoinCond tb ftb c fc = JoinCond (QualifiedIdentifier s tb, colName c) (QualifiedIdentifier s ftb, colName fc)
+    toJoinCond :: (Text, Integer) -> (Text, Integer) -> Column -> Column -> JoinCond
+    toJoinCond (tb, tLvl) (ftb, fLvl) c fc = JoinCond (QualifiedIdentifier s tb, colName c, tLvl) (QualifiedIdentifier s ftb, colName fc, fLvl)
 
 addFiltersOrdersRanges :: ApiRequest -> Either ApiRequestError (ReadRequest -> ReadRequest)
 addFiltersOrdersRanges apiRequest = foldr1 (liftA2 (.)) [
@@ -304,7 +316,7 @@ addProperty f (path, a) (Node rn forest) =
         maybeNode = find fnd forst
           where
             fnd :: ReadRequest -> Bool
-            fnd (Node (_,(n,_,_,_)) _) = n == name
+            fnd (Node (_,(n,_,_,_,_)) _) = n == name
 
 mutateRequest :: ApiRequest -> TableName -> [Text] -> [FieldName] -> Either Response MutateRequest
 mutateRequest apiRequest tName pkCols fldNames = mapLeft apiRequestError $
@@ -340,7 +352,7 @@ fieldNames (Node (sel, _) forest) =
   map (fst . view _1) (select sel) ++ map colName fks
   where
     fks = concatMap (fromMaybe [] . f) forest
-    f (Node (_, (_, Just Relation{relFColumns=cols, relType=Parent}, _, _)) _) = Just cols
+    f (Node (_, (_, Just Relation{relFColumns=cols, relType=Parent}, _, _, _)) _) = Just cols
     f _ = Nothing
 
 -- Traditional filters(e.g. id=eq.1) are added as root nodes of the LogicTree

src/PostgREST/QueryBuilder.hs

@@ -1,4 +1,6 @@
 {-# LANGUAGE FlexibleInstances    #-}
+{-# LANGUAGE FlexibleContexts    #-}
+{-# LANGUAGE DuplicateRecordFields    #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 {-|
 Module      : PostgREST.QueryBuilder
@@ -206,7 +208,7 @@ pgFmtLit x =
 
 requestToCountQuery :: Schema -> DbRequest -> SqlQuery
 requestToCountQuery _ (DbMutate _) = undefined
-requestToCountQuery schema (DbRead (Node (Select _ _ logicForest _ _ _, (mainTbl, _, _, _)) _)) =
+requestToCountQuery schema (DbRead (Node (Select{where_=logicForest}, (mainTbl, _, _, _, _)) _)) =
  unwords [
    "SELECT pg_catalog.count(*)",
    "FROM ", fromQi qi,
@@ -216,15 +218,15 @@ requestToCountQuery schema (DbRead (Node (Select _ _ logicForest _ _ _, (mainTbl
    qi = removeSourceCTESchema schema mainTbl
 
 requestToQuery :: Schema -> Bool -> DbRequest -> SqlQuery
-requestToQuery schema isParent (DbRead (Node (Select colSelects tbls logicForest joinConds_ ordts range, (nodeName, maybeRelation, _, _)) forest)) =
+requestToQuery schema isParent (DbRead (Node (Select colSelects tbls logicForest joinConds_ ordts range, (nodeName, maybeRelation, _, _, level)) forest)) =
   query
   where
     mainTbl = fromMaybe nodeName (tableName . relTable <$> maybeRelation)
-    qi = removeSourceCTESchema schema mainTbl
-    toQi = removeSourceCTESchema schema
+    tableAlias tbl = tbl <> "_" <> show level
+    qi = QualifiedIdentifier "" $ tableAlias mainTbl
     query = unwords [
       "SELECT " <> intercalate ", " (map (pgFmtSelectItem qi) colSelects ++ selects),
-      "FROM " <> intercalate ", " (map (fromQi . toQi) tbls),
+      "FROM " <> intercalate ", " (map (\t -> fromQi (removeSourceCTESchema schema t) <> " AS " <> pgFmtIdent (tableAlias t)) tbls),
       unwords joins,
       ("WHERE " <> intercalate " AND " (map (pgFmtLogicTree qi) logicForest ++ map pgFmtJoinCond joinConds_))
         `emptyOnFalse` (null logicForest && null joinConds_),
@@ -234,21 +236,21 @@ requestToQuery schema isParent (DbRead (Node (Select colSelects tbls logicForest
     (joins, selects) = foldr getQueryParts ([],[]) forest
 
     getQueryParts :: Tree ReadNode -> ([SqlFragment], [SqlFragment]) -> ([SqlFragment], [SqlFragment])
-    getQueryParts (Node n@(_, (name, Just Relation{relType=Child,relTable=Table{tableName=table}}, alias, _)) forst) (j,s) = (j,sel:s)
+    getQueryParts (Node n@(_, (name, Just Relation{relType=Child,relTable=Table{tableName=table}}, alias, _, _)) forst) (j,s) = (j,sel:s)
       where
         sel = "COALESCE(("
            <> "SELECT json_agg(" <> pgFmtIdent table <> ".*) "
            <> "FROM (" <> subquery <> ") " <> pgFmtIdent table
            <> "), '[]') AS " <> pgFmtIdent (fromMaybe name alias)
            where subquery = requestToQuery schema False (DbRead (Node n forst))
-    getQueryParts (Node n@(_, (name, Just Relation{relType=Parent,relTable=Table{tableName=table}}, alias, _)) forst) (j,s) = (joi:j,sel:s)
+    getQueryParts (Node n@(_, (name, Just Relation{relType=Parent,relTable=Table{tableName=table}}, alias, _, _)) forst) (j,s) = (joi:j,sel:s)
       where
         aliasOrName = fromMaybe name alias
         localTableName = pgFmtIdent $ table <> "_" <> aliasOrName
         sel = "row_to_json(" <> localTableName <> ".*) AS " <> pgFmtIdent aliasOrName
         joi = " LEFT JOIN LATERAL( " <> subquery <> " ) AS " <> localTableName <> " ON TRUE "
           where subquery = requestToQuery schema True (DbRead (Node n forst))
-    getQueryParts (Node n@(_, (name, Just Relation{relType=Many,relTable=Table{tableName=table}}, alias, _)) forst) (j,s) = (j,sel:s)
+    getQueryParts (Node n@(_, (name, Just Relation{relType=Many,relTable=Table{tableName=table}}, alias, _, _)) forst) (j,s) = (j,sel:s)
       where
         sel = "COALESCE (("
            <> "SELECT json_agg(" <> pgFmtIdent table <> ".*) "
@@ -422,8 +424,10 @@ pgFmtFilter table (Filter fld (OpExpr hasNot oper)) = notOp <> " " <> case oper
      (find ((==) . toLower $ v) ["null","true","false"])
 
 pgFmtJoinCond :: JoinCond -> SqlFragment
-pgFmtJoinCond (JoinCond (qi, cName) (fQi, fcName)) =
-  pgFmtColumn (removeSourceCTESchema (qiSchema qi) (qiName qi)) cName <> " = " <> pgFmtColumn (removeSourceCTESchema (qiSchema fQi) (qiName fQi)) fcName
+pgFmtJoinCond (JoinCond (qi, cName, lvl) (fQi, fcName, fLvl)) =
+  let qiAlias = QualifiedIdentifier "" (qiName qi <> "_" <> show lvl)
+      fQiAlias = QualifiedIdentifier "" (qiName fQi <> "_" <> show fLvl) in
+  pgFmtColumn qiAlias cName <> " = " <> pgFmtColumn fQiAlias fcName
 
 pgFmtLogicTree :: QualifiedIdentifier -> LogicTree -> SqlFragment
 pgFmtLogicTree qi (Expr hasNot op forest) = notOp <> " (" <> intercalate (" " <> show op <> " ") (pgFmtLogicTree qi <$> forest) <> ")"

src/PostgREST/Types.hs

@@ -274,13 +274,14 @@ type SelectItem = (Field, Maybe Cast, Maybe Alias, Maybe RelationDetail)
 -- | Path of the embedded levels, e.g "clients.projects.name=eq.." gives Path ["clients", "projects"]
 type EmbedPath = [Text]
 data Filter = Filter { field::Field, opExpr::OpExpr } deriving (Show, Eq)
-data JoinCond = JoinCond (QualifiedIdentifier, FieldName) (QualifiedIdentifier, FieldName) deriving (Show, Eq)
+data JoinCond = JoinCond (QualifiedIdentifier, FieldName, Level) (QualifiedIdentifier, FieldName, Level) deriving (Show, Eq)
+type Level = Integer
 
 data ReadQuery = Select { select::[SelectItem], from::[TableName], where_::[LogicTree], joinConds::[JoinCond], order::[OrderTerm], range_::NonnegRange } deriving (Show, Eq)
 data MutateQuery = Insert { in_::TableName, insPkCols::[Text], qPayload::PayloadJSON, onConflict:: Maybe PreferResolution, where_::[LogicTree], returning::[FieldName] }
                  | Delete { in_::TableName, where_::[LogicTree], returning::[FieldName] }
                  | Update { in_::TableName, qPayload::PayloadJSON, where_::[LogicTree], returning::[FieldName] } deriving (Show, Eq)
-type ReadNode = (ReadQuery, (NodeName, Maybe Relation, Maybe Alias, Maybe RelationDetail))
+type ReadNode = (ReadQuery, (NodeName, Maybe Relation, Maybe Alias, Maybe RelationDetail, Level))
 type ReadRequest = Tree ReadNode
 type MutateRequest = MutateQuery
 data DbRequest = DbRead ReadRequest | DbMutate MutateRequest

test/Feature/QuerySpec.hs

@@ -427,6 +427,77 @@ spec = do
     it "can detect fk relations through views to tables in the public schema" $
       get "/consumers_view?select=*,orders_view{*}" `shouldRespondWith` 200
 
+    context "tables with self reference foreign keys" $ do
+      context "one self reference foreign key" $ do
+        it "embeds parents recursively" $
+          get "/family_tree?id=in.(3,4)&select=id,parent(id,name,parent(*))" `shouldRespondWith`
+            [json|[
+              { "id": "3", "parent": { "id": "1", "name": "Parental Unit", "parent": null } },
+              { "id": "4", "parent": { "id": "2", "name": "Kid One", "parent": { "id": "1", "name": "Parental Unit", "parent": null } } }
+            ]|]
+            { matchHeaders = [matchContentTypeJson] }
+
+        it "embeds childs recursively" $
+          get "/family_tree?id=eq.1&select=id,name, childs:family_tree.parent(id,name,childs:family_tree.parent(id,name))" `shouldRespondWith`
+            [json|[{
+              "id": "1", "name": "Parental Unit", "childs": [
+                { "id": "2", "name": "Kid One", "childs": [ { "id": "4", "name": "Grandkid One" } ] },
+                { "id": "3", "name": "Kid Two", "childs": [ { "id": "5", "name": "Grandkid Two" } ] }
+              ]
+            }]|] { matchHeaders = [matchContentTypeJson] }
+
+        it "embeds parent and then embeds childs" $
+          get "/family_tree?id=eq.2&select=id,name,parent(id,name,childs:family_tree.parent(id,name))" `shouldRespondWith`
+            [json|[{
+              "id": "2", "name": "Kid One", "parent": {
+                "id": "1", "name": "Parental Unit", "childs": [ { "id": "2", "name": "Kid One" }, { "id": "3", "name": "Kid Two"} ]
+              }
+            }]|] { matchHeaders = [matchContentTypeJson] }
+
+      context "two self reference foreign keys" $ do
+        it "embeds parents" $
+          get "/organizations?select=id,name,referee(id,name),auditor(id,name)&id=eq.3" `shouldRespondWith`
+            [json|[{
+              "id": 3, "name": "Acme",
+              "referee": {
+                "id": 1,
+                "name": "Referee Org"
+              },
+              "auditor": {
+                "id": 2,
+                "name": "Auditor Org"
+              }
+            }]|] { matchHeaders = [matchContentTypeJson] }
+
+        it "embeds childs" $ do
+          get "/organizations?select=id,name,refereeds:organizations.referee(id,name)&id=eq.1" `shouldRespondWith`
+            [json|[{
+              "id": 1, "name": "Referee Org",
+              "refereeds": [
+                {
+                  "id": 3,
+                  "name": "Acme"
+                },
+                {
+                  "id": 4,
+                  "name": "Umbrella"
+                }
+              ]
+            }]|] { matchHeaders = [matchContentTypeJson] }
+          get "/organizations?select=id,name,auditees:organizations.auditor(id,name)&id=eq.2" `shouldRespondWith`
+            [json|[{
+              "id": 2, "name": "Auditor Org",
+              "auditees": [
+                {
+                  "id": 3,
+                  "name": "Acme"
+                },
+                {
+                  "id": 4,
+                  "name": "Umbrella"
+                }
+              ]
+            }]|] { matchHeaders = [matchContentTypeJson] }
 
   describe "ordering response" $ do
     it "by a column asc" $

test/fixtures/data.sql

@@ -346,3 +346,16 @@ INSERT INTO tiobe_pls VALUES ('Java', 1), ('C', 2), ('Python', 4);
 
 TRUNCATE TABLE only_pk CASCADE;
 INSERT INTO only_pk VALUES (1), (2);
+
+TRUNCATE TABLE family_tree CASCADE;
+INSERT INTO family_tree VALUES ('1', 'Parental Unit', NULL);
+INSERT INTO family_tree VALUES ('2', 'Kid One', '1');
+INSERT INTO family_tree VALUES ('3', 'Kid Two', '1');
+INSERT INTO family_tree VALUES ('4', 'Grandkid One', '2');
+INSERT INTO family_tree VALUES ('5', 'Grandkid Two', '3');
+
+TRUNCATE TABLE organizations CASCADE;
+INSERT INTO organizations VALUES (1, 'Referee Org', null, null);
+INSERT INTO organizations VALUES (2, 'Auditor Org', null, null);
+INSERT INTO organizations VALUES (3, 'Acme', 1, 2);
+INSERT INTO organizations VALUES (4, 'Umbrella', 1, 2);

test/fixtures/privileges.sql

@@ -66,6 +66,8 @@ GRANT ALL ON TABLE
     , employees
     , tiobe_pls
     , only_pk
+    , family_tree
+    , organizations
 TO postgrest_test_anonymous;
 
 GRANT INSERT ON TABLE insertonly TO postgrest_test_anonymous;

test/fixtures/schema.sql

@@ -1374,3 +1374,19 @@ create table test.tiobe_pls(
   name text primary key,
   rank smallint
 );
+
+create table test.family_tree (
+  id text not null primary key,
+  name text not null,
+  parent text
+);
+alter table only test.family_tree add constraint pptr foreign key (parent) references test.family_tree(id);
+
+create table test.organizations (
+  id integer primary key,
+  name text,
+  referee integer,
+  auditor integer
+);
+alter table only test.organizations add constraint pptr1 foreign key (referee) references test.organizations(id);
+alter table only test.organizations add constraint pptr2 foreign key (auditor) references test.organizations(id);