Note: As of the June 2018 update to ArcGIS Online, domains can be added and updated directly in ArcGIS Online through the Data tab in the hosted feature layer's item page. For more details, refer to ArcGIS Online: Define attribute lists and ranges.
The instructions provided describe how to add coded value domains to a hosted feature service from the REST endpoint in ArcGIS Online. The instructions can also be applied in other instances, such as editing the values inside of a coded value domain for the feature service.
Note: Each layer may have to be opened to update the parameter if there are multiple layers in the service.
Warning: The instructions below include making changes to essential parts of your hosted feature service. It is recommended that you make a copy of the original JSON before proceeding. Esri cannot guarantee results from incorrect modifications while following these instructions. Therefore, use caution and proceed at your own risk. Any problems encountered as a result of making these modifications are not supported by Esri Technical Support.
Note: Ensure the feature service is not shared publicly before using this workflow.
Note: If the error, "There are no services available" is returned when visiting the ArcGIS REST Administrator Directory, the hosted feature service is shared with 'Everyone' (public).
Note: It is also possible to update or change the order of domains for a feature service as desired using this step.