topic Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only) in Python Questions

Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

JosephArmbruster — Mon, 05 Feb 2018 19:23:20 GMT

Hey everyone,

It's been ages since i've had to resort to the forums, but the time has come... This is issue is occurring with:

10.3.0.4322

AND

10.5.1.7333

Problem: When a layer is added to the TOC, just as you see in the snippet below, feature selections will no longer be respected (or at least detected) by geoprocessing tools.

Description: The symptom of the problem is that obtaining the feature selection count of a geoprocessing layer in a python toolbox is inconsistent. I've pinned it down to some issue with the way Arc (or ArcPy) is handling layers by Name. Here are some snippets:

# make this an absolute path to some feature class in a geodatabase, you only need a minimum of two features to reproduce the issue, i'm using polygons.

path = #path to your polygon feature class with at least two features in it.

mxd = arcpy.mapping.MapDocument('CURRENT')
new_layer_name = os.path.basename(path)
arcpy.MakeFeatureLayer_management(path, new_layer_name)
new_layer = arcpy.mapping.Layer(new_layer_name)
arcpy.mapping.AddLayer(mxd.activeDataFrame, new_layer_name, 'BOTTOM')

del new_layer
del mxd

Use the code above in a geoprocessing tool to add a layer to the map.

Now, use the code below in a separate geoprocessing tool, to report the number of features selected in the map.

desc = arcpy.Describe(input_feature_class)
if desc.FIDSet:
messages.addMessage('selection made')
# you'll never get here with the layer above!!
else:
messages.addMessage('no selection made')
# you'll always get here even with a selection 😞

# count will always be the entire feature class count, since no selection was registered
# to the layer....
feature_count = int(arcpy.GetCount_management(input_feature_class).getOutput(0)

Notes:
- If you use the code above to add the feature class to the map. Remove it from the toc (right click, remove) and add it using arc catalog (drag-drop), the feature selection will STILL not work. Hence why I suggest it has something to do with the internal name resolution.

- If you start a new ArcMap instance, add the layer by drag-dropping it from Arc Catalog, the selection WILL work. If you remove this layer and add it using the code above, all subsequent selections will NOT be respected.

I look forward to hearing from ESRI support.

Let me know if you have any questions,

Joseph Armbruster

0Lat Inc, Orlando Florida.

joseph.armbruster@0lat.com

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

RebeccaStrauch__GISP — Mon, 05 Feb 2018 20:29:52 GMT

Joseph, welcome to the Geonet Community forums. First, don't get discouraged, but you should move this to the https://community.esri.com/community/developers/gis-developers/python?sr=search&searchId=83795ee7-e01d-4395-9caa-aa12c1990bab&searchIndex=0‌ , since the ArcGIS API for Python is actually a newer product, mainly used for administration portals and for doing some analysis, simple mapping etc. outside of ArcMap/Catalog/Pro. You can move it using the pulldown under Actions in the upper right corner. I would have done this for you, but I don't have those rights in this space. By adding the @ and space name it actually gets tagged. I'll also add https://community.esri.com/community/gis/mapping?sr=search&searchId=b9b071a9-f5ac-4fac-92ae-c17ef9679487&searchIndex=4‌

Also, always good to post code using one of the options /blogs/dan_patterson/2016/08/14/script-formatting?sr=search&searchId=1753a87a-9033-4500-afb8-f4155c08ef32&searchIndex=4‌ That way, the pesky spaces etc of python don't cause issues and there are line numbers to help with feedback.

Also, tech support doesn't necessarily follow the forums. It will be other users (and yes, their are serious developers that are active in the forums).

Again, don't get discouraged on using the forums. Very active these days.

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

JoshuaBixby — Sat, 11 Dec 2021 17:21:14 GMT

I haven't had a chance to test the code yet, but on first glance the following two lines caught my eye:

desc = arcpy.Describe(input_feature_class)
if desc.FIDSet:‍‍

Since feature classes don't support FIDSet, feature layers do, the code above should generate an AttributeError if passed a feature class. Are you seeing an AttributeError or are you passing it a feature layer?

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

JosephArmbruster — Tue, 06 Feb 2018 00:12:00 GMT

Joshua, the problem is not as trivial as an AttributeError, hence why I added the 'serious ESRI devs only 🙂

For clarification, the parameter type is a GPFeatureLayer but I access the parameter valueAsText and pass it into Describe. Which is the correct ArcPythonic way of doing this. FIDSet is a valid attribute in my test case.

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

JamesCrandall — Sat, 11 Dec 2021 17:21:16 GMT

It looks like you are trying to get the count on the feature class, not what is loaded in the mxd document.

feature_count = int(arcpy.GetCount_management(input_feature_class).getOutput(0)‍‍‍

This is working for a layer loaded in the TOC:

mxd = arcpy.mapping.MapDocument('CURRENT')
df = arcpy.mapping.ListDataFrames(mxd)[0]
lyr = arcpy.mapping.ListLayers(mxd, "SomeLayerInTOC", df)[0]
desc = arcpy.Describe(lyr)
feature_count = desc.FIDSet
print("Number of selected features: {}".format(len(feature_count.split(";"))))

‍‍‍‍‍‍‍

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

XanderBakker — Sat, 11 Dec 2021 17:21:19 GMT

I have given it a shot and noticed a few things, but did manage to get it to work (although I'm using 10.6). What I did was:

I have an mxd open with a layer in it:

I ran this code in the Python window of my ArcMap session:

import arcpy
import os
arcpy.env.overwriteOutput = True

path = r'C:\GeoNet\Selection\test.gdb\myLines' #path to your polygon feature class with at least two features in it.
mxd = arcpy.mapping.MapDocument('CURRENT')
new_layer_name = os.path.basename(path)
arcpy.MakeFeatureLayer_management(path, new_layer_name) # this already adds the layer to the data frame
move_layer = arcpy.mapping.ListLayers(mxd, new_layer_name, mxd.activeDataFrame)[0]
ref_layer = arcpy.mapping.ListLayers(mxd, "", mxd.activeDataFrame)[-1]
arcpy.mapping.MoveLayer(mxd.activeDataFrame, ref_layer, move_layer, "AFTER")

del move_layer
del ref_layer
del mxd‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Notice that there are a few difference with the code you provided:

I have added the overwriteOutput = True on line 3 since the new_layer_name will already exist after the first run and throw an error
on line 8, when you create a feature layer, it is already added to ArcMap (at the top, which you don't want)
You have a line of code that not added the layer but the layer name, which was wrong
On line 9 I create a layer object from the layer added and on line 10 I get a reference to the last layer in the TOC
On line 11 these layers are used to move the added layer to the bottom

Now we have the layer at he bottom of the TOC:

Next step is to do something with the tool to investigate the selection. I created a simple tool and added this script:

def main():
    import arcpy

    # GPFeatureLayer
    feature_layer = arcpy.GetParameter(0)

    desc = arcpy.Describe(feature_layer)
    fid_set = desc.FIDSet
    if fid_set == '':
        lst_fid = []
    else:
        lst_fid = fid_set.split(';')
    if len(lst_fid) > 0:
        arcpy.AddMessage('selection made: {}'.format(len(lst_fid)))
        arcpy.AddMessage(lst_fid)
    else:
        arcpy.AddMessage('no selection made: {}'.format(len(lst_fid)))
        arcpy.AddMessage(lst_fid)

    feature_count = int(arcpy.GetCount_management(feature_layer).getOutput(0))
    arcpy.AddMessage('feature count: {}'.format(feature_count))

if __name__ == '__main__':
    main()‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

It only has a single parameter (Feature Layer). When I run the tool the first time (no selection made yet) something interesting is happening:

The added layer appears twice in the list. When I select the first element it will run and yield this:

Which was to be expected since no selection was made.

I can make a selection:

And run the tool again, and this time only a single myLines is in the list:

It has a selection which is correctly detected both ways:

So apart from the fact that the layer appears twice in the list of feature layers, the tool seems to work and detect the selection.

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

JosephArmbruster — Tue, 06 Feb 2018 17:00:41 GMT

You need to add the layer just like I did to experience the issue...

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

JosephArmbruster — Tue, 06 Feb 2018 17:04:31 GMT

So, a few things here..

1. "on line 8, when you create a feature layer, it is already added to ArcMap (at the top, which you don't want)"

MakeFeatureLayer_management does not necessarily add the layer to a dataframe...

2. "You have a line of code that not added the layer but the layer name, which was wrong"

It's not wrong, that's a valid use for MakeFeatureLayer_management... It creates a feature layer, which is not necessarily attached to a data frame... Oh, andI believe the layer names passed to MakeFeatureLayer must be unique per-process. Otherwise, not sure how you would delete it once it's no longer needed, unless you can obtain the generate layer as an output parameter...

2."So apart from the fact that the layer appears twice in the list of feature layers, the tool seems to work and detect the selection."

That's a reasonably unacceptable workaround for an obvious software problem 🙂

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

XanderBakker — Sat, 11 Dec 2021 17:21:22 GMT

if I add the layer using this code (which is exactly yours apart from line 1 pointing to my featureclass):

path = r'C:\GeoNet\Selection\test.gdb\myLines'
mxd = arcpy.mapping.MapDocument('CURRENT')
new_layer_name = os.path.basename(path)
arcpy.MakeFeatureLayer_management(path, new_layer_name)
new_layer = arcpy.mapping.Layer(new_layer_name)
arcpy.mapping.AddLayer(mxd.activeDataFrame, new_layer_name, 'BOTTOM')
del new_layer
del mxd‍‍‍‍‍‍‍‍

This beautiful error is produced:

Runtime error
Traceback (most recent call last):
File "<string>", line 6, in <module>
File "c:\program files (x86)\arcgis\desktop10.6\arcpy\arcpy\utils.py", line 182, in fn_
return fn(*args, **kw)
File "c:\program files (x86)\arcgis\desktop10.6\arcpy\arcpy\mapping.py", line 49, in AddLayer
assert isinstance(add_layer, Layer)
AssertionError

And the layer is added at the top:

So, your code is not working correctly...

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

XanderBakker — Tue, 06 Feb 2018 17:25:52 GMT

MakeFeatureLayer_management does not necessarily add the layer to a dataframe...

It is the default setting in ArcMap.

If you will share the tool to other users, you will need to account for that behavior or check if it was added or not.

It's not wrong, that's a valid use for MakeFeatureLayer_management.

Make me wonder why an error is produced in my case when using your exact code...

That's a reasonably unacceptable workaround for an obvious software problem 🙂

Contact support...

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

XanderBakker — Tue, 06 Feb 2018 17:26:20 GMT

MakeFeatureLayer_management does not necessarily add the layer to a dataframe...

It is the default setting in ArcMap.

If you will share the tool to other users, you will need to account for that behavior or check if it was added or not.

It's not wrong, that's a valid use for MakeFeatureLayer_management.

Make me wonder why an error is produced in my case when using your exact code...

That's a reasonably unacceptable workaround for an obvious software problem 🙂

Contact support...

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

JosephArmbruster — Tue, 06 Feb 2018 17:27:01 GMT

Bah, copy/pasta typo... That line should be:

arcpy.mapping.AddLayer(mxd.activeDataFrame, new_layer, 'BOTTOM')

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

XanderBakker — Tue, 06 Feb 2018 17:28:43 GMT

Never seen a "typo" occur from copy and past. Might want to report it to Microsoft.

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

JosephArmbruster — Tue, 06 Feb 2018 17:39:23 GMT

Haaaaaar 🙂 That was a self inflicted post-copy-pasta wound... But still a distraction from the real issue!!

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

XanderBakker — Tue, 06 Feb 2018 17:42:31 GMT

Some last comments before I leave this thread to what it is:

You requested that only "Serious ESRI devs" should respond. Rebecca, Joshua an James are all MVP' with a large amount of experience with ArcGIS and Python
Rebecca asked you to provided the code using the syntax highlighter, which you haven't done, making it more difficult to detect problems in the code
You provided partial code using variable names that don't match the data type and aid misinterpretation of the code. Which led to the valid suggestion of Joshua that you cannot get the FIDSet of a featureclass.
I assume that you have been marking several answers as "Not helpful". If so, this is not inviting the users to keep helping you.
If you are so sure that it is a software bug, you should report it to support.

Good luck on solving it.

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

JosephArmbruster — Tue, 06 Feb 2018 18:29:09 GMT

MVP and GISP mean almost nothing to me personally. There are people who make careers out of accumulating thumbs ups, which is what it is... I've been doing this for years and typically do not have unlimited time to invest in forum interaction (reference the old, original esri forums...)

There are two people who attempted to provided material value so-far on this issue, you and Joshua, and for that Thanks! Even with the silly typo, it's not difficult to reproduce this issue. If you change that text to new_layer, you'll see 🙂

Yes, I have opened an issue with ESRI support and a working .pyt with both sides of the tool. If there was an attach file option here, i'd use it!!

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

DanPatterson_Retired — Tue, 06 Feb 2018 18:48:28 GMT

here you go

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

JosephArmbruster — Tue, 06 Feb 2018 19:07:11 GMT

Test code attached.

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

JamesCrandall — Sat, 11 Dec 2021 17:21:25 GMT

If possible, implement arcpy.GetCount on the layer in the TOC rather than the desc.FIDSet.

mxd = arcpy.mapping.MapDocument('CURRENT')
df = arcpy.mapping.ListDataFrames(mxd)[0]
lyr = arcpy.mapping.ListLayers(mxd, "SomeLayerName", df)[0]
getCountMethod = int(arcpy.GetCount_management(lyr).getOutput(0))
arcpy.AddMessage("getCountMethod: {}".format(getCountMethod))‍‍‍‍‍

That seems to work just fine, even after the layer was added programmatically from another GP tool.

Re: Arcpy.mapping.AddLayer selection Funk (serious ESRI devs only)

JosephArmbruster — Tue, 06 Feb 2018 19:25:40 GMT

James,

I use the feature layer that was provided as an input to the tool within my function. I shouldn't have to List and search for it again, if it's given to me

Also, I am not using the FIDSet for anything besides a little debug output. You could remove the lines from desc = arcpy.Describe(input_feature_class), all the way down to the 'no selection made' message if you want... same issue will surface.

The problem has something to do with the way the layer was added... because any subsequent add of a layer with the same Name will experience the issue.

Joe