Parse session variables to their correct type in mssql

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/2908
GitOrigin-RevId: d9d8811e0d0658f6396a7c94bce9b7d2deb5245e

server/src-lib/Hasura/Backends/MSSQL/Plan.hs

@@ -33,6 +33,7 @@ import Hasura.Prelude hiding (first)
 import Hasura.RQL.IR
 import Hasura.RQL.Types.Column qualified as RQL
 import Hasura.SQL.Backend
+import Hasura.SQL.Types
 import Hasura.Session
 import Language.GraphQL.Draft.Syntax qualified as G
 
@@ -66,11 +67,18 @@ prepareValueQuery sessionVariables =
     GraphQL.UVLiteral x -> pure x
     GraphQL.UVSession -> pure $ ValueExpression $ ODBC.ByteStringValue $ toStrict $ J.encode sessionVariables
     GraphQL.UVParameter _ RQL.ColumnValue {..} -> pure $ ValueExpression cvValue
-    GraphQL.UVSessionVar _typ sessionVariable -> do
+    GraphQL.UVSessionVar typ sessionVariable -> do
       value <-
         getSessionVariableValue sessionVariable sessionVariables
           `onNothing` throw400 NotFound ("missing session variable: " <>> sessionVariable)
-      pure $ ValueExpression $ ODBC.TextValue value
+      -- See https://github.com/fpco/odbc/pull/34#issuecomment-812223147
+      -- We first cast to nvarchar(max) because casting from ntext is not supported
+      CastExpression (CastExpression (ValueExpression $ ODBC.TextValue value) "nvarchar(max)")
+        <$> case typ of
+          CollectableTypeScalar baseTy ->
+            pure (scalarTypeDBName baseTy)
+          CollectableTypeArray {} ->
+            throw400 NotSupported "Array types are currently not supported in MS SQL Server"
 
 planSubscription ::
   MonadError QErr m =>

server/tests-py/queries/graphql_query/basic/author_with_permission_mssql.yaml

@@ -0,0 +1,20 @@
+description: Author can view their information only
+url: /v1/graphql
+status: 200
+headers:
+  X-Hasura-Role: user
+  X-Hasura-User-Id: '2'
+response:
+  data:
+    author:
+      - id: 2
+        name: Author 2
+
+query:
+  query: |
+    query {
+      author {
+        id
+        name
+      }
+    }

server/tests-py/queries/graphql_query/basic/setup_mssql.yaml

@@ -99,3 +99,12 @@ args:
       foreign_key_constraint_on:
         table: article_multi
         columns: ["author_id1", "author_id2"]
+
+- type: mssql_create_select_permission
+  args:
+    source: mssql
+    table: author
+    role: user
+    permission:
+      columns: "*"
+      filter: {"id":{"_eq":"X-Hasura-User-Id"}}

server/tests-py/test_graphql_queries.py

@@ -342,6 +342,10 @@ class TestGraphQLQueryBasicMSSQL:
     def test_select_query_author_pk_null(self, hge_ctx, transport):
         check_query_f(hge_ctx, self.dir() + '/select_query_author_by_pkey_null.yaml', transport)
 
+    def test_author_with_permission(self, hge_ctx, transport):
+        check_query_f(hge_ctx, self.dir() + '/author_with_permission_mssql.yaml', transport)
+
+
     @classmethod
     def dir(cls):
         return 'queries/graphql_query/basic'