server: case insensitive lookup in session variable

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3663
GitOrigin-RevId: b36666d8849a23dad209f9921f140390c2b57496

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Bug fixes and improvements
 (Add entries below in the order of server, console, cli, docs, others)
 
+- server: add custom function for case insensitive lookup in session variable in request transformation
 - server: Webhook Transforms can now delete request/response bodies explicitly.
 - server: Fix truncation of session variables with variable length column types in MSSQL (#8158)
 - server: improve baseline memory consumption for typical workloads

cabal.project

@@ -45,7 +45,7 @@ package graphql-engine
 source-repository-package
   type: git
   location: https://github.com/hasura/kriti-lang.git
-  tag: 01930d88da1a95eee1e4d5e2a1ba78752548e599
+  tag: v0.3.1
 
 source-repository-package
   type: git

cabal.project.freeze

@@ -208,7 +208,7 @@ constraints: any.Cabal ==3.2.1.0,
              jose -demos,
              any.kan-extensions ==5.2.3,
              any.keys ==3.12.3,
-             any.kriti-lang ==0.3.0,
+             any.kriti-lang ==0.3.1,
              any.lens ==5.1,
              lens -benchmark-uniplate -dump-splices +inlining -j +test-hunit +test-properties +test-templates +trustworthy,
              any.lens-aeson ==1.1.3,

docs/graphql/core/api-reference/syntax-defs.rst

@@ -2075,6 +2075,35 @@ RequestTransformation
      - :ref:`TemplateEngine`
      - Template language to be used for this transformation. Default: "Kriti"
 
+.. note::
+
+   HGE provides the following functions that can be used in the template:
+
+   - ``not``: This function takes a boolean and returns its negation.
+
+     eg::
+
+        > {{not true}}
+        false
+   
+   - ``escapeUri``: This function takes a string and escapes it as per URI specification.
+
+     eg::
+
+        > {{ escapeUri "?foo=bar/baz" }}
+        "%3Ffoo%3Dbar%2Fbaz"
+        
+
+   - ``getSessionVariable``: This function takes a string and returns the session variable of the given name. This function can throw the following errors:
+
+     - Session variable {variable name} not found
+     - Session variable name should be a string
+
+     eg::
+
+        > {{getSessionVariable "myVariableName"}}
+        "myVariableValue"
+
 .. _TransformHeaders:
 
 TransformHeaders

server/src-lib/Hasura/RQL/DDL/WebhookTransforms.hs

@@ -37,9 +37,9 @@ import Data.Text.Encoding qualified as TE
 import Data.Validation qualified as V
 import Hasura.Incremental (Cacheable)
 import Hasura.Prelude hiding (first)
-import Hasura.Session (SessionVariables)
-import Kriti (SerializedError (..), runKriti)
-import Kriti.Error (serialize)
+import Hasura.Session (SessionVariables, getSessionVariableValue, mkSessionVariable)
+import Kriti (SerializedError (..), runKriti, runKritiWith)
+import Kriti.Error (CustomFunctionError (..), serialize)
 import Kriti.Parser (parser)
 import Network.HTTP.Client.Transformable qualified as HTTP
 import Network.URI qualified as URI
@@ -73,7 +73,8 @@ data ReqTransformCtx = ReqTransformCtx
   { tcUrl :: Maybe J.Value,
     tcBody :: J.Value,
     tcSessionVars :: J.Value,
-    tcQueryParams :: Maybe J.Value
+    tcQueryParams :: Maybe J.Value,
+    tcFunctions :: M.HashMap T.Text (J.Value -> Either CustomFunctionError J.Value)
   }
 
 instance J.ToJSON ReqTransformCtx where
@@ -441,7 +442,7 @@ mkReqTemplateTransform :: TemplatingEngine -> TemplateText -> ReqTransformCtx ->
 mkReqTemplateTransform engine (TemplateText template) ReqTransformCtx {..} =
   let context = [("$body", tcBody), ("$session_variables", tcSessionVars)] <> catMaybes [("$query_params",) <$> tcQueryParams, ("$base_url",) <$> tcUrl]
    in case engine of
-        Kriti -> first (TransformErrorBundle . pure . J.toJSON . serialize) $ runKriti template context
+        Kriti -> first (TransformErrorBundle . pure . J.toJSON . serialize) $ runKritiWith (template) context tcFunctions
 
 -- | Construct a Template Transformation function for Responses
 mkRespTemplateTransform :: TemplatingEngine -> TemplateText -> RespTransformCtx -> Either TransformErrorBundle J.Value
@@ -456,8 +457,19 @@ buildReqTransformCtx url sessionVars reqData =
     { tcUrl = Just $ J.toJSON url,
       tcBody = fromMaybe J.Null $ J.decode @J.Value =<< view HTTP.body reqData,
       tcSessionVars = J.toJSON sessionVars,
-      tcQueryParams = Just $ J.toJSON $ bimap TE.decodeUtf8 (fmap TE.decodeUtf8) <$> view HTTP.queryParams reqData
+      tcQueryParams = Just $ J.toJSON $ bimap TE.decodeUtf8 (fmap TE.decodeUtf8) <$> view HTTP.queryParams reqData,
+      tcFunctions = M.singleton "getSessionVariable" getSessionVar
     }
+  where
+    getSessionVar :: J.Value -> Either CustomFunctionError J.Value
+    getSessionVar inp = case inp of
+      J.String txt ->
+        case sessionVarValue of
+          Just x -> Right $ J.String x
+          Nothing -> Left . CustomFunctionError $ "Session variable \"" <> txt <> "\" not found"
+        where
+          sessionVarValue = sessionVars >>= getSessionVariableValue (mkSessionVariable txt)
+      _ -> Left $ CustomFunctionError "Session variable name should be a string"
 
 buildRespTransformCtx :: ReqTransformCtx -> BL.ByteString -> RespTransformCtx
 buildRespTransformCtx reqCtx respBody =

server/tests-py/queries/v1/metadata/test_webhook_transform_custom_functions.yaml

@@ -0,0 +1,79 @@
+- description: Test Webhook Transform getSessionVariable function | success
+  url: /v1/metadata
+  headers:
+    X-Hasura-Role: admin
+  status: 200
+  response:
+    body: some value
+    headers: []
+    method: GET
+    webhook_url: http://localhost:1234/
+  query:
+    type: test_webhook_transform
+    args:
+      webhook_url: http://localhost:1234
+      body:
+        hello: world
+      session_variables:
+        myVariable: some value
+      request_transform:
+        body: '{{ getSessionVariable "myVariable" }}'
+        template_engine: Kriti
+
+- description: Test Webhook Transform getSessionVariable function | non existant session variable
+  url: /v1/metadata
+  headers:
+    X-Hasura-Role: admin
+  status: 200
+  response:
+    body:
+    - error_code: Function Error
+      source_position:
+        end_column: 51
+        start_line: 0
+        end_line: 0
+        start_column: 23
+      message: Session variable "this_variable_doesnt_exist" not found
+    headers: []
+    method: GET
+    webhook_url: http://localhost:1234/
+  query:
+    type: test_webhook_transform
+    args:
+      webhook_url: http://localhost:1234
+      body:
+        hello: world
+      session_variables:
+        myVariable: some value
+      request_transform:
+        body: '{{ getSessionVariable "this_variable_doesnt_exist" }}'
+        template_engine: Kriti
+
+- description: Test Webhook Transform function | wrong function name
+  url: /v1/metadata
+  headers:
+    X-Hasura-Role: admin
+  status: 200
+  response:
+    body:
+    - error_code: Function Error
+      source_position:
+        end_column: 15
+        start_line: 0
+        end_line: 0
+        start_column: 4
+      message: Function fooFunction is not defined.
+    headers: []
+    method: GET
+    webhook_url: http://localhost:1234/
+  query:
+    type: test_webhook_transform
+    args:
+      webhook_url: http://localhost:1234
+      body:
+        hello: world
+      session_variables:
+        myVariable: some value
+      request_transform:
+        body: '{{ fooFunction "myVariable" }}'
+        template_engine: Kriti

server/tests-py/test_metadata.py

@@ -238,6 +238,9 @@ class TestMetadata:
     def test_webhook_transform_bad_eval(self, hge_ctx):
         check_query_f(hge_ctx, self.dir() + '/test_webhook_transform_bad_eval.yaml')
 
+    def test_webhook_transform_custom_functions(self, hge_ctx):
+        check_query_f(hge_ctx, self.dir() + '/test_webhook_transform_custom_functions.yaml')
+
     @pytest.mark.skipif(
         os.getenv('HASURA_GRAPHQL_PG_SOURCE_URL_1') == os.getenv('HASURA_GRAPHQL_PG_SOURCE_URL_2') or
         os.getenv('HASURA_GRAPHQL_PG_SOURCE_URL_1') is None or