Correct inner join to use proper aliases (#1978)

"_" was used for all the internal json_agg aliases. Now an alias
with "_" plus a local table name is used.

Co-authored-by: Cole Arendt <cole.arendt@outlook.com>

src/PostgREST/Query/QueryBuilder.hs

@@ -50,7 +50,7 @@ readRequestToQuery (Node (Select colSelects mainQi tblAlias implJoins logicFores
     (joins, selects) = foldr getJoinsSelects ([],[]) forest
 
 getJoinsSelects :: ReadRequest -> ([H.Snippet], [H.Snippet]) -> ([H.Snippet], [H.Snippet])
-getJoinsSelects rr@(Node (_, (name, Just Relationship{relCardinality=card,relTable=Table{tableName=table}}, alias, _, Just joinType, _)) _) (j,s) =
+getJoinsSelects rr@(Node (_, (name, Just Relationship{relCardinality=card,relTable=Table{tableName=table}}, alias, _, Just joinType, _)) _) (joins,selects) =
   let subquery = readRequestToQuery rr in
   case card of
     M2O _ ->
@@ -59,21 +59,25 @@ getJoinsSelects rr@(Node (_, (name, Just Relationship{relCardinality=card,relTab
           sel = H.sql ("row_to_json(" <> localTableName <> ".*) AS " <> pgFmtIdent aliasOrName)
           joi = (if joinType == JTInner then " INNER" else " LEFT")
             <> " JOIN LATERAL( " <> subquery <> " ) AS " <> H.sql localTableName <> " ON TRUE " in
-      (joi:j,sel:s)
+      (joi:joins,sel:selects)
     _ -> case joinType of
       JTInner ->
         let aliasOrName = fromMaybe name alias
-            localTableName = pgFmtIdent $ table <> "_" <> aliasOrName
-            sel = H.sql $ localTableName <> "._ AS " <> pgFmtIdent aliasOrName
-            joi = "INNER JOIN LATERAL( SELECT json_agg(_) AS _ FROM (" <> subquery <> " ) _) AS " <>
-                  H.sql localTableName <> " ON " <> H.sql localTableName <> "IS NOT NULL" in
-        (joi:j,sel:s)
+            locTblName = table <> "_" <> aliasOrName
+            localTableName = pgFmtIdent locTblName
+            internalTableName = pgFmtIdent $ "_" <> locTblName
+            sel = H.sql $ localTableName <> "." <> internalTableName <> " AS " <> pgFmtIdent aliasOrName
+            joi = "INNER JOIN LATERAL(" <>
+                    "SELECT json_agg(" <> H.sql internalTableName <> ") AS " <> H.sql internalTableName <>
+                    "FROM (" <> subquery <> " ) AS " <> H.sql internalTableName <>
+                  ") AS " <> H.sql localTableName <> " ON " <> H.sql localTableName <> "IS NOT NULL" in
+        (joi:joins,sel:selects)
       JTLeft ->
         let sel = "COALESCE (("
                <> "SELECT json_agg(" <> H.sql (pgFmtIdent table) <> ".*) "
                <> "FROM (" <> subquery <> ") " <> H.sql (pgFmtIdent table) <> " "
                <> "), '[]') AS " <> H.sql (pgFmtIdent (fromMaybe name alias)) in
-        (j,sel:s)
+        (joins,sel:selects)
 getJoinsSelects _ _ = ([], [])
 
 mutateRequestToQuery :: MutateRequest -> H.Snippet

test/Feature/EmbedInnerJoinSpec.hs

@@ -220,6 +220,26 @@ spec =
         [json| [{"id":3,"client":{"id":2}}, {"id":4,"client":{"id":2}}] |]
         { matchHeaders = [matchContentTypeJson] }
 
+    it "works with many one-to-many relationships" $ do
+      -- https://github.com/PostgREST/postgrest/issues/1977
+      get "/client?select=id,name,contact!inner(name),clientinfo!inner(other)" `shouldRespondWith`
+        [json|[
+          {"id":1,"name":"Walmart","contact":[{"name":"Wally Walton"}, {"name":"Wilma Wellers"}],"clientinfo":[{"other":"123 Main St"}]},
+          {"id":2,"name":"Target", "contact":[{"name":"Tabby Targo"}],"clientinfo":[{"other":"456 South 3rd St"}]},
+          {"id":3,"name":"Big Lots","contact":[{"name":"Bobby Bots"}, {"name":"Bonnie Bits"}, {"name":"Billy Boats"}],"clientinfo":[{"other":"789 Palm Tree Ln"}]}
+        ]|]
+        { matchHeaders = [matchContentTypeJson] }
+      get "/client?select=id,name,contact!inner(name),clientinfo!inner(other)&contact.name=eq.Wally%20Walton" `shouldRespondWith`
+        [json|[
+          {"id":1,"name":"Walmart","contact":[{"name":"Wally Walton"}],"clientinfo":[{"other":"123 Main St"}]}
+        ]|]
+        { matchHeaders = [matchContentTypeJson] }
+      get "/client?select=id,name,contact!inner(name),clientinfo!inner(other)&clientinfo.other=eq.456%20South%203rd%20St" `shouldRespondWith`
+        [json|[
+          {"id":2,"name":"Target","clientinfo":[{"other":"456 South 3rd St"}],"contact":[{"name":"Tabby Targo"}]}
+        ]|]
+        { matchHeaders = [matchContentTypeJson] }
+
 notDefaultConfig :: SpecWith ((), Application)
 notDefaultConfig =
   describe "Embedding with a default inner join(db-embed-default-join = 'inner')" $ do

test/fixtures/data.sql

@@ -706,4 +706,13 @@ TRUNCATE TABLE test.trade_unions CASCADE;
 INSERT INTO test.trade_unions (id, name) VALUES (1,'union-1'), (2,'union-2'), (3, 'union-3'), (4, 'union-4');
 
 TRUNCATE TABLE test.suppliers_trade_unions CASCADE;
-INSERT INTO test.suppliers_trade_unions (supplier_id, trade_union_id) VALUES (1,1), (1,2), (2,3), (2,4);
+INSERT INTO test.suppliers_trade_unions (supplier_id, trade_union_id) VALUES (1,1), (1,2), (2,3), (2,4);
+
+TRUNCATE TABLE test.client CASCADE;
+INSERT INTO test.client (id,name) values (1,'Walmart'),(2,'Target'),(3,'Big Lots');
+
+TRUNCATE TABLE test.contact CASCADE;
+INSERT INTO test.contact (id,name, clientid) values (1,'Wally Walton',1),(2,'Wilma Wellers',1),(3,'Tabby Targo',2),(4,'Bobby Bots',3),(5,'Bonnie Bits',3),(6,'Billy Boats',3) returning *;
+
+TRUNCATE TABLE test.clientinfo CASCADE;
+INSERT INTO test.clientinfo (id,clientid, other) values (1,1,'123 Main St'),(2,2,'456 South 3rd St'),(3,3,'789 Palm Tree Ln');

test/fixtures/privileges.sql

@@ -156,6 +156,9 @@ GRANT ALL ON TABLE
     , products_suppliers
     , trade_unions
     , suppliers_trade_unions
+    , client
+    , clientinfo
+    , contact
 TO postgrest_test_anonymous;
 
 GRANT INSERT ON TABLE insertonly TO postgrest_test_anonymous;

test/fixtures/schema.sql

@@ -2347,4 +2347,22 @@ create table suppliers_trade_unions(
   supplier_id int references suppliers(id),
   trade_union_id int references trade_unions(id),
   primary key (supplier_id, trade_union_id)
-);
+);
+
+
+CREATE TABLE client (
+  id int primary key
+, name text
+);
+
+CREATE TABLE contact (
+  id int primary key
+, name text
+, clientid int references client(id)
+);
+
+CREATE TABLE clientinfo (
+  id serial primary key
+, clientid int unique references client(id)
+, other text
+);