add 'app.Validator' field for ReadJSON, ReadXML, ReadMsgPack, ReadYAML, ReadForm, ReadQuery data validation, defaults to empty but can be set-ed to 3rd-party packages

Former-commit-id: e42d9be5928edcdaad4579c008f741b1a7d97da9

iris.go

@@ -155,6 +155,9 @@ type Application struct {
 	// See `Context#Tr` method for request-based translations.
 	I18n *i18n.I18n
 
+	// Validator is the request body validator, defaults to nil.
+	Validator context.Validator
+
 	// view engine
 	view view.View
 	// used for build
@@ -309,6 +312,33 @@ func (app *Application) I18nReadOnly() context.I18nReadOnly {
 	return app.I18n
 }
 
+// Validate validates a value and returns nil if passed or
+// the failure reason if does not.
+func (app *Application) Validate(v interface{}) error {
+	if app.Validator == nil {
+		return nil
+	}
+
+	// val := reflect.ValueOf(v)
+	// if val.Kind() == reflect.Ptr && !val.IsNil() {
+	// 	val = val.Elem()
+	// }
+
+	// if val.Kind() == reflect.Struct && val.Type() != timeType {
+	// 	return app.Validator.Struct(v)
+	// }
+
+	// no need to check the kind, underline lib does it but in the future this may change (look above).
+	err := app.Validator.Struct(v)
+	if err != nil {
+		if !strings.HasPrefix(err.Error(), "validator: ") {
+			return err
+		}
+	}
+
+	return nil
+}
+
 var (
 	// HTML view engine.
 	// Shortcut of the kataras/iris/view.HTML.