Add validator that checks local part of email address.

validators.go

@@ -237,6 +237,27 @@ func ValidDomainNameTLD(err error) ValidatorFunc {
 	}
 }
 
+/* ValidEmailLocal checks a valid local part for email address */
+func ValidEmailLocal(err error) ValidatorFunc {
+	EInvalidEmail := errors.New("invalid email address")
+	validLetters := ValidLettersGeneric(
+		"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ._-+",
+		fallbackError(err, EInvalidEmail),
+	)
+	return func(field *FormField, ctx context.Context) error {
+		/* check for allowed symbols in local part */
+		if err := validLetters(field, ctx); err != nil {
+			return err
+		}
+		/* common checks */
+		local := field.GetString()
+		if len(local) > 64 || local[0] == '.' || local[len(local)-1] == '.' || strings.Index(local, "..") != -1 {
+			return fallbackError(err, EInvalidEmail)
+		}
+		return nil
+	}
+}
+
 /* ValidEmail checks if field contains a valid email address */
 func ValidEmail(err error) ValidatorFunc {
 	EInvalidEmail := errors.New("invalid email address")