Symbolizing Polygon and Point Outputs from Python Script Tool

Question

I have a python script tool that outputs points and polygons. I want to symbolize them based on a field but I'm having a hard time doing that in my code rather than manually. When I run ApplySymbologyFromLayer in the python window, the symbology applies just fine. However, when I try to do something similar at the end of my script tool, I get no errors but the symbology is unchanged. What am I missing to make this work?

Here is the code for adding the polygons. It is essentially the same for the points. I got some advice from ChatGPT while looking for a solution so I'm open to anything that needs to be remedied from that too.

polygonLayerTemplate = r"J:\User\Coding\PolygonsTemplate.lyrx" 
    polygonLayerName = "Polygons"

for lyr in activeMap.listLayers():
        if lyr.name == polygonLayerName:
            activeMap.removeLayer(lyr)  # remove old version to avoid duplicates
    polygonLayer = activeMap.addDataFromPath(polygonsFeatureClass)
    Layer = activeMap.listLayers(polygonLayerName)[0]
    arcpy.management.ApplySymbologyFromLayer(
        in_layer=Layer,
        in_symbology_layer=polygonLayerTemplate,
        symbology_fields="VALUE_FIELD Name Name",
        update_symbology="UPDATE"
    )

TylerT · Answer

@HaydenWelch, Good to know.  Thank you.

Hayden Welch · Answer

Docs are sometimes inconsistent on that. There's some pretty aggressive parameter conversion that goes on with the direct API functions.

E.g. Any function that has 2 literal flags can either take a flag or a Boolean (True/False == "INVERT"/"NOT-INVERT")

If you ever get the chance, check out the fixargs decorator that wraps every function and you'll see what I mean.

TylerT · Answer

One thing you might check is your symbology_fields argument.  The docs show this as a list of lists vice a string.

Tyler