How to calculate a field in a non-hosted web map

[Dawn_Scott]

I have a volume field in my hydrant web map.  It is not hosted, it is a feature service that I created in Enterprise, stored on my GIS server.  My field crews are flushing hydrants and storing flow time in minutes (FLOWTIME) and gallons per minute (GPM).  I want to calculate total volume from those two fields.  It's really simple, but evidently I can only calculate a field in a hosted web map.

I have been told to create a python script and run it as a task overnight, but this seems really clunky to me.  What am I missing?  There must be a way to do this in a web map that is not hosted.

[JayJohnsonWashoeCounty]

Are you wanting to store the calculated value in a field or just display it/use it in a webmap?  If you just want to show the value in a webmap, you can certainly use Arcade to create an Attribute Expression...

[Dawn_Scott]

Displaying and using it in a webmap would be fine.  But, the 'calculate' option is not available for the volume field in my webmap, because the feature service is not hosted.  So, how do I do this?

[JayJohnsonWashoeCounty]

Dawn,

You need to create a Custom Expression.  In your web map, go to Symbology for the hydrant layer and create a New Expression.

In the code window that pops up, use Arcade to do your calculation (conceptually FLOWTIME X GPM).

Now you have a sort of "on-the-fly" calculation that can be used to symbolize your hydrants by the result of that calculation.

You can do a similar thing within your Attribute pop-up.

Hope this helps.