1 files changed, 31 insertions, 0 deletions
diff --git a/app/validators/feature_flag_user_xids_validator.rb b/app/validators/feature_flag_user_xids_validator.rb
new file mode 100644
index 00000000000..a840993a94b
--- /dev/null
+++ b/app/validators/feature_flag_user_xids_validator.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+class FeatureFlagUserXidsValidator < ActiveModel::EachValidator
+  USERXID_MAX_LENGTH = 256
+
+  def validate_each(record, attribute, value)
+    self.class.validate_user_xids(record, attribute, value, attribute)
+  end
+
+  class << self
+    def validate_user_xids(record, attribute, user_xids, error_message_attribute_name)
+      unless user_xids.is_a?(String) && !user_xids.match(/[\n\r\t]|,,/) && valid_xids?(user_xids.split(","))
+        record.errors.add(attribute,
+                          "#{error_message_attribute_name} must be a string of unique comma separated values each #{USERXID_MAX_LENGTH} characters or less")
+      end
+    end
+
+    private
+
+    def valid_xids?(user_xids)
+      user_xids.uniq.length == user_xids.length &&
+        user_xids.all? { |xid| valid_xid?(xid) }
+    end
+
+    def valid_xid?(user_xid)
+      user_xid.present? &&
+        user_xid.strip == user_xid &&
+        user_xid.length <= USERXID_MAX_LENGTH
+    end
+  end
+end