Problem: Unable to view domains for a feature layer enabled with coded value domains in a web map
Feature services published to ArcGIS Online do not maintain domains and subtypes applied and configured in ArcGIS for Desktop. After the data is published to ArcGIS Online, the attribute table and pop-ups show the raw coded values rather than the domain or subtype descriptions. Additionally, when editing or adding new features, the domain and subtype descriptions are not presented in the traditional drop-down list.
This is a known issue. The domains that are set up and integrated with the subtypes are not set solely on the fields directly. The domains do not display in ArcGIS Online because they are set through subtypes, and subtypes do not display in ArcGIS Online as a drop-down list, they only show as the raw coded value.
Solution or Workaround
A possible solution is to bypass the subtypes option and set up domains directly on each field. Follow the steps below to assign the domains to the individual fields in ArcMap before publishing the data to ArcGIS Online.
Create a new coded value domain (if needed)
In ArcCatalog or the Catalog window, expand the Catalog tree, right-click the geodatabase, and click Properties.
Click the Domains tab.
Click the first empty field under Domain Name and type a name for the new domain.
Do not use special characters in domain names, such as backslashes, if using a PostgreSQL database.
Press the Tab key or click the new domain's description field and type a description for the domain.
Click the field next to Field Type, click the drop-down arrow, and select the type of attribute field to apply to the domain.
Click the field next to Domain Type, click the drop-down arrow, and click Coded Values from the list of domain types.
Click the first empty field under Coded Values and type the first valid code.
Press the Tab key or click the new coded value's Description field. Type a user-friendly description for this coded value.
Repeat steps 7 and 8 until all valid values and their descriptions have been typed.
Click Apply to create the new domain in the geodatabase, or click OK to create the domain and close the dialog box.
Apply the appropriate domain to the specific field
In ArcCatalog or the Catalog window, expand the Catalog tree and browse to the feature class being published.
Right-click the feature class, and select Properties.
In the Fields tab, select the field to assign the domain.
In the Field Properties box, click Domain, and assign the correct domain.
Click Apply > OK.
Publish the feature class to ArcGIS Online. The drop-down list for domains is now available when editing the attributes in the feature's pop-up window.