topic Re: Updating Web Map Layer Definition Expression Filters via Python 2.4 in ArcGIS API for Python Questions

Updating Web Map Layer Definition Expression Filters via Python 2.4

BBarbs — Wed, 12 Feb 2025 16:05:32 GMT

Hello Community,

I recently upgraded ArcGIS Pro to 3.4.2, which included Python 2.4.0 and the new Map() module. I am working on updating one of my scripts and have run into a road block I was hoping someone could help me with.

My map has several grouped layers whose definition expressions are updated by python script. My usual method of defining each layer by title doesn't work anymore with the new mapping module. Does anyone know how I can point to my layers in Python 2.4's new module?

Here is a sample of my previous method:

import arcgis
from arcgis.map import Map
from arcgis.gis import GIS
gis = GIS("home")

# New method to grab web map in Python 2.4

wm_item = gis.content.get("<item id>")

webmap = Map(item=wm_item)

# report update date
reportDTSQL = '02012025'

# (Old, not-working method of updating layer expression-- NEEDS UPDATING)
# get layers of interest

enrolledLyr = webmap.get_layer(title="Locations Enrolled Only")

# apply new filter expression to each layer's json

enrolledLyr["layerDefinition"]["definitionExpression"] = f"(category = 'Active') AND ({reportDTSQL})"

# Update web map object with new json

webmap.update_layer(dict(EnrolledLyr))

Thank you for any help!

Re: Updating Web Map Layer Definition Expression Filters via Python 2.4

Clubdebambos — Thu, 13 Feb 2025 11:40:06 GMT

Hi @BBarbs,

I've abandoned using some of the new classes in version 2.4.0 and going direct to the WebMap definition as shown below, code commented for workflow.

from arcgis.gis import GIS ## access ArcGIS Online agol = GIS("home") ## get teh WebMap as an Item object wm_item = agol.content.get("WM_ITEM_ID") ## get the WebMap JSON definition wm_item_data = wm_item.get_data() ## What layer do you want to update? lyr_name = "LAYER_NAME" ## What filter do you want to apply? filter_exp = "FIELD = 'VALUE'" ## for each layer in the WebMap for lyr in wm_item_data["operationalLayers"]: ## if it is a Group Layer if lyr["layerType"] == "GroupLayer": ## for each layer in teh group layer for grp_lyr in lyr["layers"]: ## if the layer title is the one we want if grp_lyr["title"] == lyr_name: ## apply the filter grp_lyr["layerDefinition"]["definitionExpression"] = filter_exp ## if the layer of interest is not a group layer and matched the layer name elif lyr["title"] == lyr_name: ## apply the fiter lyr["layerDefinition"]["definitionExpression"] = filter_exp ## create the update dictionary update_properties = {"text" : wm_item_data} ## apply the update to the WebMap object (updating JSON definition) wm_item.update( item_properties = update_properties )

I have asked for the get_layer() to be reinstated, you can vote for it here.

All the best,

Glen

Re: Updating Web Map Layer Definition Expression Filters via Python 2.4

BBarbs — Thu, 13 Feb 2025 16:20:03 GMT

Thank you so much, this works perfect! I voted for your idea, hopefully it gets brought back!