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.
