allow extra validator

this will extra validations for schema elements
example : lookup some value in a database an provide an error

Author: lazedo

src/jesse_state.erl

@@ -26,6 +26,7 @@
 %% API
 -export([ add_to_path/2
         , get_allowed_errors/1
+        , get_extra_validator/1
         , get_current_path/1
         , get_current_schema/1
         , get_current_schema_id/1
@@ -49,6 +50,7 @@
 %% Includes
 -include("jesse_schema_validator.hrl").
 
+-type extra_validator() :: fun((jesse:json_term(), state()) -> state()) | undefined.
 %% Internal datastructures
 -record( state
        , { root_schema        :: jesse:json_term()
@@ -68,6 +70,7 @@
                                           jesse:json_term() |
                                           ?not_found
                                             )
+         , extra_validator    :: extra_validator()
          , id                 :: http_uri:uri() | 'undefined'
          }
        ).
@@ -148,13 +151,17 @@ new(JsonSchema, Options) ->
                                  , Options
                                  , ?default_schema_loader_fun
                                  ),
+  ExtraValidator = proplists:get_value( extra_validator
+                                      , Options
+                                      ),
   NewState = #state{ root_schema        = JsonSchema
                    , current_path       = []
                    , allowed_errors     = AllowedErrors
                    , error_list         = []
                    , error_handler      = ErrorHandler
                    , default_schema_ver = DefaultSchemaVer
                    , schema_loader_fun  = LoaderFun
+                   , extra_validator    = ExtraValidator
                    },
   set_current_schema(NewState, JsonSchema).
 
@@ -385,3 +392,5 @@ load_schema(#state{schema_loader_fun = LoaderFun}, SchemaURI) ->
       %% io:format("load_schema: ~p\n", [{_C, _E, erlang:get_stacktrace()}]),
       ?not_found
   end.
+
+get_extra_validator(#state{extra_validator=Fun}) -> Fun.

src/jesse_validator_draft3.erl

@@ -48,7 +48,8 @@
                     | ?not_in_range
                     | ?wrong_length
                     | ?wrong_size
-                    | ?wrong_type.
+                    | ?wrong_type
+                    | ?external_error.
 
 -type data_error_type() :: data_error()
                          | {data_error(), binary()}.
@@ -209,11 +210,11 @@ check_value(Value, [{?DISALLOW, Disallow} | Attrs], State) ->
 check_value(Value, [{?EXTENDS, Extends} | Attrs], State) ->
   NewState = check_extends(Value, Extends, State),
   check_value(Value, Attrs, NewState);
-check_value(_Value, [], State) ->
-  State;
 check_value(Value, [{?REF, RefSchemaURI} | Attrs], State) ->
   NewState = validate_ref(Value, RefSchemaURI, State),
   check_value(Value, Attrs, NewState);
+check_value(Value, [], State) ->
+  check_external_validation(Value, State);
 check_value(Value, [_Attr | Attrs], State) ->
   check_value(Value, Attrs, State).
 
@@ -1031,3 +1032,10 @@ add_to_path(State, Property) ->
 %% @private
 remove_last_from_path(State) ->
   jesse_state:remove_last_from_path(State).
+
+%% @private
+check_external_validation(Value, State) ->
+    case jesse_state:get_extra_validator(State) of
+        undefined -> State;
+        Fun -> Fun(Value, State)
+    end.

src/jesse_validator_draft4.erl

@@ -65,7 +65,8 @@
                     | ?too_many_properties
                     | ?wrong_length
                     | ?wrong_size
-                    | ?wrong_type.
+                    | ?wrong_type
+                    | ?external_error.
 
 -type data_error_type() :: data_error()
                          | {data_error(), binary()}.
@@ -246,11 +247,11 @@ check_value(Value, [{?ONEOF, Schemas} | Attrs], State) ->
 check_value(Value, [{?NOT, Schema} | Attrs], State) ->
   NewState = check_not(Value, Schema, State),
   check_value(Value, Attrs, NewState);
-check_value(_Value, [], State) ->
-  State;
 check_value(Value, [{?REF, RefSchemaURI} | Attrs], State) ->
   NewState = validate_ref(Value, RefSchemaURI, State),
   check_value(Value, Attrs, NewState);
+check_value(Value, [], State) ->
+  check_external_validation(Value, State);
 check_value(Value, [_Attr | Attrs], State) ->
   check_value(Value, Attrs, State).
 
@@ -1362,3 +1363,9 @@ valid_datetime(DateTimeBin) ->
     _ ->
       false
   end.
+
+check_external_validation(Value, State) ->
+    case jesse_state:get_extra_validator(State) of
+        undefined -> State;
+        Fun -> Fun(Value, State)
+    end.