Getting layer IDs using ArcPy?

Question

I am working in an ArcMap session, I've checked the option to get an ID for each of the layers in my document, so anyone has it.

Now, what I need is a way to get these values within a python script (to copy that automatically in a table): there's no such information in the layer's properties reached by a describe, nor from the .mapping module.

Answer 1

In ArcGIS Pro you can do this:

cim_version = 'V2'
aprx = arcpy.mp.ArcGISProject(aprx_file)
map0 = aprx.listMaps()[0]
lyr0 = map0.listLayers()[0]
def0 = lyr0.getDefinition(cim_version)
# serviceLayerID will be -1 if "allow assign. unique ids to layers"
# was not check on the Data Frame properties
# in that case, serviceLayerID are in order from 0 -> len(layers) - 1
# & includes GroupLayers (can check lyr0.isGroupLayer, etc)
serviceLayerID = def0.serviceLayerID

Answer 2

After testing this in ArcGIS 10.3, and according to the documentation available for Layer and Describe in arcpy, and also this thread: https://geonet.esri.com/thread/178341, this functionality does not yet exist. You cannot access the layer ID from arcpy. You may be able to access it through ArcObjects if you have the knowledge.

As a workaround, can you enter the ID into the Credits or Description fields? You can access both of these fields through arcpy.