fix: handle queries on non-existing table gracefully

src/PostgREST/Error.hs

@@ -45,6 +45,7 @@ import PostgREST.SchemaCache.Relationship (Cardinality (..),
                                            RelationshipsMap)
 import PostgREST.SchemaCache.Routine      (Routine (..),
                                            RoutineParam (..))
+import PostgREST.SchemaCache.Table        (Table (..))
 import Protolude
 
 
@@ -82,6 +83,7 @@ data ApiRequestError
   | UnacceptableSchema [Text]
   | UnsupportedMethod ByteString
   | ColumnNotFound Text Text
+  | TableNotFound Text Text [Table]
   | GucHeadersError
   | GucStatusError
   | PutMatchingPkError
@@ -128,6 +130,7 @@ instance PgrstError ApiRequestError where
   status UnacceptableSchema{}        = HTTP.status406
   status UnsupportedMethod{}         = HTTP.status405
   status ColumnNotFound{}            = HTTP.status400
+  status TableNotFound{}             = HTTP.status404
   status GucHeadersError             = HTTP.status500
   status GucStatusError              = HTTP.status500
   status PutMatchingPkError          = HTTP.status400
@@ -285,6 +288,12 @@ instance JSON.ToJSON ApiRequestError where
   toJSON (ColumnNotFound relName colName) = toJsonPgrstError
     SchemaCacheErrorCode04 ("Could not find the '" <> colName <> "' column of '" <> relName <> "' in the schema cache") Nothing Nothing
 
+  toJSON (TableNotFound schemaName relName tbls) = toJsonPgrstError
+    SchemaCacheErrorCode05
+    ("Could not find the table '" <> schemaName <> "." <> relName <> "' in the schema cache")
+    Nothing
+    (JSON.String <$> tableNotFoundHint schemaName relName tbls)
+
 -- |
 -- If no relationship is found then:
 --
@@ -382,6 +391,16 @@ noRpcHint schema procName params allProcs overloadedProcs =
       | null overloadedProcs = Fuzzy.getOne fuzzySetOfProcs procName
       | otherwise            = (procName <>) <$> Fuzzy.getOne fuzzySetOfParams (listToText params)
 
+-- |
+-- Do a fuzzy search in all tables in the same schema and return closest result
+tableNotFoundHint :: Text -> Text -> [Table] -> Maybe Text
+tableNotFoundHint schema tblName tblList
+  = fmap (\tbl -> "Perhaps you meant the table '" <> schema <> "." <> tbl <> "'") perhapsTable
+    where
+      perhapsTable = Fuzzy.getOne fuzzyTableSet tblName
+      fuzzyTableSet = Fuzzy.fromList [ tableName tbl | tbl <- tblList, tableSchema tbl == schema]
+
+
 compressedRel :: Relationship -> JSON.Value
 -- An ambiguousness error cannot happen for computed relationships TODO refactor so this mempty is not needed
 compressedRel ComputedRelationship{} = JSON.object mempty
@@ -672,6 +691,7 @@ data ErrorCode
   | SchemaCacheErrorCode02
   | SchemaCacheErrorCode03
   | SchemaCacheErrorCode04
+  | SchemaCacheErrorCode05
   -- JWT authentication errors
   | JWTErrorCode00
   | JWTErrorCode01
@@ -719,6 +739,7 @@ buildErrorCode code = case code of
   SchemaCacheErrorCode02 -> "PGRST202"
   SchemaCacheErrorCode03 -> "PGRST203"
   SchemaCacheErrorCode04 -> "PGRST204"
+  SchemaCacheErrorCode05 -> "PGRST205"
 
   JWTErrorCode00         -> "PGRST300"
   JWTErrorCode01         -> "PGRST301"

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

src/PostgREST/SchemaCache/Identifiers.hs

@@ -25,6 +25,7 @@ instance Hashable RelIdentifier
 
 -- | Represents a pg identifier with a prepended schema name "schema.table".
 -- When qiSchema is "", the schema is defined by the pg search_path.
+-- TODO: Refactor this, we also use QI for procedure names
 data QualifiedIdentifier = QualifiedIdentifier
   { qiSchema :: Schema
   , qiName   :: TableName