Best way to auto-calculate a field?

Question

In either the Web AppBuilder, Field maps, or in a Dashboard (Portal 10.8.1), is there a way to auto-populate a feature's "Response Time" attribute field, based on two other date fields ("Report Date/Time" and "On-Scene Date/Time") any time a new feature is added?

jcarlson · Answer

Not so! That's one of the great things about the ArcGIS Python API. Any machine that has a Python environment with the module installed can run that script, provided the user who "signs in" in the script has the permissions necessary to edit the layer.

Check out Anaconda for tools to manage Python envs. If you do set up an automated process, it's good to have it running in a dedicated environment.

JasonCyphers · Answer

Thanks!  I'm assuming this is something that runs on the server?  I'm just a "high-level" end user...I don't do much much on the server-side of things, but could get out GIS-IT dept. involved if need be.

jcarlson · Answer

This is precisely the kind of situation that make Data Expressions so great in Dashboards, but you can't get at them in your version of Enterprise.

The next best thing would be a Python script that just evaluates frequently to update the field.

from arcgis import GIS

gis = GIS('your portal url', 'username')

# get layer
fl = gis.content.get('itemid of layer').layers[0] # or whatever layer index applies

# calculation expression
expr = {
    'field': 'response_time',
    'value': 'DATEDIFF(minute, on_scene_time, dispatch_time)'
}

# calculate field
fl.calculate(calc_expression=expr)

Note that the SQL expression used to calculate the field will vary depending on your server, but DATEDIFF is pretty standard.

A script like that would take very little time to run, and could be scheduled to fire every few minutes, or whatever interval makes sense for your users.