fix: handle queries on non-existing table gracefully

src/PostgREST/Plan.hs

@@ -153,18 +153,20 @@ dbActionPlan dbAct conf apiReq sCache = case dbAct of
 
 wrappedReadPlan :: QualifiedIdentifier -> AppConfig -> SchemaCache -> ApiRequest -> Bool -> Either Error CrudPlan
 wrappedReadPlan  identifier conf sCache apiRequest@ApiRequest{iPreferences=Preferences{..},..} headersOnly = do
-  rPlan <- readPlan identifier conf sCache apiRequest
-  (handler, mediaType)  <- mapLeft ApiRequestError $ negotiateContent conf apiRequest identifier iAcceptMediaType (dbMediaHandlers sCache) (hasDefaultSelect rPlan)
+  qi <- mapLeft ApiRequestError $ findTable identifier (dbTables sCache)
+  rPlan <- readPlan qi conf sCache apiRequest
+  (handler, mediaType)  <- mapLeft ApiRequestError $ negotiateContent conf apiRequest qi iAcceptMediaType (dbMediaHandlers sCache) (hasDefaultSelect rPlan)
   if not (null invalidPrefs) && preferHandling == Just Strict then Left $ ApiRequestError $ InvalidPreferences invalidPrefs else Right ()
-  return $ WrappedReadPlan rPlan SQL.Read handler mediaType headersOnly identifier
+  return $ WrappedReadPlan rPlan SQL.Read handler mediaType headersOnly qi
 
 mutateReadPlan :: Mutation -> ApiRequest -> QualifiedIdentifier -> AppConfig -> SchemaCache -> Either Error CrudPlan
 mutateReadPlan  mutation apiRequest@ApiRequest{iPreferences=Preferences{..},..} identifier conf sCache = do
-  rPlan <- readPlan identifier conf sCache apiRequest
-  mPlan <- mutatePlan mutation identifier apiRequest sCache rPlan
+  qi <- mapLeft ApiRequestError $ findTable identifier (dbTables sCache)
+  rPlan <- readPlan qi conf sCache apiRequest
+  mPlan <- mutatePlan mutation qi apiRequest sCache rPlan
   if not (null invalidPrefs) && preferHandling == Just Strict then Left $ ApiRequestError $ InvalidPreferences invalidPrefs else Right ()
-  (handler, mediaType)  <- mapLeft ApiRequestError $ negotiateContent conf apiRequest identifier iAcceptMediaType (dbMediaHandlers sCache) (hasDefaultSelect rPlan)
-  return $ MutateReadPlan rPlan mPlan SQL.Write handler mediaType mutation identifier
+  (handler, mediaType)  <- mapLeft ApiRequestError $ negotiateContent conf apiRequest qi iAcceptMediaType (dbMediaHandlers sCache) (hasDefaultSelect rPlan)
+  return $ MutateReadPlan rPlan mPlan SQL.Write handler mediaType mutation qi
 
 callReadPlan :: QualifiedIdentifier -> AppConfig -> SchemaCache -> ApiRequest -> InvokeMethod -> Either Error CallReadPlan
 callReadPlan identifier conf sCache apiRequest@ApiRequest{iPreferences=Preferences{preferHandling, invalidPrefs},..} invMethod = do
@@ -745,6 +747,13 @@ validateAggFunctions aggFunctionsAllowed (Node rp@ReadPlan {select} forest)
   | not aggFunctionsAllowed && any (isJust . csAggFunction) select = Left AggregatesNotAllowed
   | otherwise = Node rp <$> traverse (validateAggFunctions aggFunctionsAllowed) forest
 
+-- | Lookup table in the schema cache before creating read plan
+findTable :: QualifiedIdentifier -> TablesMap -> Either ApiRequestError QualifiedIdentifier
+findTable qi@QualifiedIdentifier{..} tableMap =
+  case HM.lookup qi tableMap of
+    Nothing -> Left (TableNotFound qiSchema qiName (HM.elems tableMap))
+    Just _ -> Right qi
+
 addFilters :: ResolverContext -> ApiRequest -> ReadPlanTree -> Either ApiRequestError ReadPlanTree
 addFilters ctx ApiRequest{..} rReq =
   foldr addFilterToNode (Right rReq) flts
@@ -967,7 +976,7 @@ mutatePlan mutation qi ApiRequest{iPreferences=Preferences{..}, ..} SchemaCache{
     typedColumnsOrError = resolveOrError ctx tbl `traverse` S.toList iColumns
 
 resolveOrError :: ResolverContext -> Maybe Table -> FieldName -> Either ApiRequestError CoercibleField
-resolveOrError _ Nothing _ = Left NotFound
+resolveOrError _ Nothing _ = Left NotFound -- TODO: control never reaches here since #3869, should be fixed when fixing #3906
 resolveOrError ctx (Just table) field =
   case resolveTableFieldName table field Nothing of
     CoercibleField{cfIRType=""} -> Left $ ColumnNotFound (tableName table) field