Runtime Error Rerunning Arcpy Update Cursor Script

Question

The following script works to update coordinates in my ArcGIS feature class, but if I run it twice in a row from ArcMap on the same geodatabase feature class, I get a "RuntimeError: Unexpected Operation[outputZoneTrack FeatureClass name]" error on the "updateCursor.updateRow(row)". If I run it on a dataset, then run it on a different dataset, I can then re-run it on the first dataset again with no problem. I just can't run it on the same dataset twice in a row. Why does this error occur when I run the script twice in a row on the same dataset?

outputZoneTrack = "C:\\Temp\\geodatabase.gdb\\ozt"
outputWorkspace = os.path.split(outputZoneTrack)[0]
outputZoneTrackName = os.path.split(outputZoneTrack)[1]

arcpy.env.overwriteOutput = True
if arcpy.Exists(outputZoneTrack):
    arcpy.Delete_management(outputZoneTrack)

spatial_reference = arcpy.SpatialReference(4326) #Use WGS84 so coordinates are calculated in Lat/Long
with arcpy.da.UpdateCursor(outputZoneTrack, ["ZSTARTLAT", "ZSTARTLON", "ZENDLAT", "ZENDLON", "SHAPE@"], "", spatial_reference) as updateCursor:
    for row in updateCursor:

        row[0] = row[4].firstPoint.Y
        row[1] = row[4].firstPoint.X
        row[2] = row[4].lastPoint.Y
        row[3] = row[4].lastPoint.X
        updateCursor.updateRow(row)

mxd = arcpy.mapping.MapDocument("CURRENT")
    for lyr in arcpy.mapping.ListLayers(mxd):
        if lyr.name == "Segment Oil Zones":
            if lyr.supports("DATASOURCE"):
                lyr.replaceDataSource(outputWorkspace, "FILEGDB_WORKSPACE", outputZoneTrackName, True)
                lyr.name = "Segment Oil Zones"
                lyr.visible = True
                arcpy.AddMessage("\nOiling Zone Snapped to ACP Segments: ON\n")
                arcpy.RefreshTOC()

Note - this problem only occurs if the script is run from ArcMap and the feature class is loaded within the ArcMap TOC - I can run it multiple times in a row on the same dataset from ArcCatalog.

Answer 1

UPDATED. This works. The real issue this script could not be run twice in a row on the same feature class appears to have something to do with being locked by the layer in the current MXD after the 1st run. So I made the script to change the data path on that layer when running, then change it back at the end of the script.

arcpy.env.overwriteOutput = True
if arcpy.Exists(outputZoneTrack):
    arcpy.Delete_management(outputZoneTrack)

outputZoneTrack = "C:\\Temp\\geodatabase.gdb\\ozt"
outputWorkspace = os.path.split(outputZoneTrack)[0]
outputZoneTrackName = os.path.split(outputZoneTrack)[1]

mxd = arcpy.mapping.MapDocument("CURRENT")
for lyr in arcpy.mapping.ListLayers(mxd):
    if lyr.name == "Segment Oil Zones":
        if lyr.supports("DATASOURCE"):
            lyr.replaceDataSource(outputWorkspace, "FILEGDB_WORKSPACE", outputZoneTrackName + "_Temp", True)
            lyr.name = "Segment Oil Zones TEMP"
            lyr.visible = False
            arcpy.AddMessage("\nOiling Zone Snapped to ACP Segments: OFF\n")
            arcpy.RefreshTOC()



spatial_reference = arcpy.SpatialReference(4326) #Use WGS84 so coordinates are calculated in Lat/Long
with arcpy.da.UpdateCursor(outputZoneTrack, ["ZSTARTLAT", "ZSTARTLON", "ZENDLAT", "ZENDLON", "SHAPE@"], "", spatial_reference) as updateCursor:
    for row in updateCursor:

        row[0] = row[4].firstPoint.Y
        row[1] = row[4].firstPoint.X
        row[2] = row[4].lastPoint.Y
        row[3] = row[4].lastPoint.X
        updateCursor.updateRow(row)

mxd = arcpy.mapping.MapDocument("CURRENT")
    for lyr in arcpy.mapping.ListLayers(mxd):
        if lyr.name == "Segment Oil Zones TEMP":
            if lyr.supports("DATASOURCE"):
                lyr.replaceDataSource(outputWorkspace, "FILEGDB_WORKSPACE", outputZoneTrackName, True)
                lyr.name = "Segment Oil Zones"
                lyr.visible = True
                arcpy.AddMessage("\nOiling Zone Snapped to ACP Segments: ON\n")
                arcpy.RefreshTOC()

Answer 2

You are attempting to use outputZoneTrack before it is defined. Try defining it before testing if it exists and before attempting to delete it. (I'm not certain this will fix your issue, but it does appear to be an issue that needs fixing.)

Ie, replace this:

arcpy.env.overwriteOutput = True
if arcpy.Exists(outputZoneTrack):
    arcpy.Delete_management(outputZoneTrack)

outputZoneTrack = "C:\\Temp\\geodatabase.gdb\\ozt"

with this:

outputZoneTrack = "C:\\Temp\\geodatabase.gdb\\ozt"

arcpy.env.overwriteOutput = True
if arcpy.Exists(outputZoneTrack):
    print "Deleting {}".format(outputZoneTrack)
    arcpy.AddMessage("Deleting {}".format(outputZoneTrack))
    arcpy.Delete_management(outputZoneTrack)

(I've also added debug lines, print and AddMessage, which will at least make it clear when it's actually running Delete_management.)

Answer 3

You are using an arcpy.da.cursor. They are notorious for putting schema locks on feature classes. You will need to delete your cursor at the end of the iteration to free up the schema lock.

 del row
 del updateCursor

You may just need to delete the cursor not the row.