HOW TO

Exploring layer fields in ArcGIS using arcpy.ListFields with group layers

Last Published: October 23, 2024

Summary

This technical article provides a comprehensive guide on how to use the arcpy.ListFields function to access and explore layer fields in ArcGIS, specifically focusing on group layers.

When working with group layers in ArcGIS, accessing layer fields can be challenging due to the limitations of the arcpy.ListFields function. While the function works normally for individual layers, it does not directly work on group layers.

Cause

While the arcpy.ListFields function works fine with individual layers on the map, however, when iterating between layers on the map that includes group layers as well, the input is accepted as "group_name\layer_name" whereas the acceptable value in arcpy.ListFields is "group_name/layer_name"

Procedure

While iterating the layers on a map we can add an 'if' clause that checks if the layer name contains a backslash (\). Henceforth we store the layer name in a variable and splitting them by backslashes, gives us two strings - group name and layer name. Hence in the arcpy.ListFields function we can pass the parameter as f"{group_name}/{layer_name}" where group_name and layer_name are two variables. This way, we can utilize the functionality of arcpy.ListFields functions with group layers as well.
Below is a sample script:

#To iterate through all the layers and print their fields
import arcpy
aprx = arcpy.mp.ArcGISProject("CURRENT") #refer maps of the current ArcGIS Pro project
maps = aprx.listMaps() #retrieve list of all the maps in the project
map = maps[0] #referring the first map in the project
lyrs = map.listLayers() # retrieve list  of layers on that map
for lyr in lyrs:
    try:
        if "\\" in lyr.longName: #if the layer is inside a group, then the name would include a "\"
            group_name = lyr.longName.split("\\")[0]
            layer_name = lyr.longName.split("\\")[1]
            layer_path =group_name+"/"+layer_name 
            print("layer name="+layer_path)
            fields = arcpy.ListFields(layer_path)
            for field in fields:
                print(field.name)
            continue    
            
    except:
        print()
    else:
        try:
            if not arcpy.ListFields(lyr.longName):
                print()
            count= count+1
            print("layer name="+lyr.longName)
            fields=arcpy.ListFields(lyr.longName)
            for field in fields:
                print(field.name)
        except:
            print() #when we retrieve the list of layers the name of group layer is also retrieved, hence we need to exclude that value

Article ID: 000033307

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