Build sql for inserting multiple rows

src/App.hs

@@ -101,7 +101,7 @@ app v1schema reqBody req =
     ([table], "POST") ->
       handleJsonObj reqBody $ \obj -> do
         let qt = QualifiedTable schema (cs table)
-            query = insertInto qt (map cs $ keys obj) (elems obj)
+            query = insertInto qt (map cs $ keys obj) [(elems obj)]
             echoRequested = lookup "Prefer" hdrs == Just "return=representation"
         row <- H.maybeEx query
         let (Identity insertedJson) = fromMaybe (Identity "{}" :: Identity Text) row

src/PgQuery.hs

@@ -108,15 +108,20 @@ returningStarT s = s { B.stmtTemplate = B.stmtTemplate s <> " RETURNING *" }
 deleteFrom :: QualifiedTable -> PStmt
 deleteFrom t = B.Stmt ("delete from " <> fromQt t) empty True
 
-insertInto :: QualifiedTable -> [T.Text] -> [JSON.Value] -> PStmt
+insertInto :: QualifiedTable -> [T.Text] -> [[JSON.Value]] -> PStmt
 insertInto t [] _ = B.Stmt
   ("insert into " <> fromQt t <> " default values returning *") empty True
 insertInto t cols vals = B.Stmt
   ("insert into " <> fromQt t <> " (" <>
     T.intercalate ", " (map pgFmtIdent cols) <>
-    ") values ("
+    ") values "
-    <> T.intercalate ", " (map insertableValue vals)
+    <> T.intercalate ", "
-    <> ") returning row_to_json(" <> fromQt t <> ".*)")
+      (map (\v -> "("
+          <> T.intercalate ", " (map insertableValue v)
+          <> ")"
+        ) vals
+      )
+    <> " returning row_to_json(" <> fromQt t <> ".*)")
   empty True
 
 insertSelect :: QualifiedTable -> [T.Text] -> [JSON.Value] -> PStmt