arcpy.management.CalculateField running into "Cannot acquire a lock" error

MichaelMarlatt1

Hello,

I have a python notebook that I've been running in Pro v3.0 that compares a handful of point feature classes to two different versions of a polygon feature class and tells me which points are not in the same polygon in both versions.  

The problem I am having is after adding columns to the point feature classes (via arcpy.management.AddField), I keep getting a "Cannot acquire a lock" error when I try to calculate values into those fields.  These feature classes are all in a file geodatabase that nobody else is using except me.  

What do I need to do between the first CalculateField and the second to get this to work?  It is the same feature class involved both times.

I use CalculateField many times elsewhere in the notebook but after arcpy.management.SelectLayerByLocation (or ByAttribute).  This only is happening when it follows .AddField.

Here are the relevant sections of the notebook:

 

#adding the fields
arcpy.management.AddField(NewDlnLayer,DlnChangedField,"TEXT",field_length=1)
arcpy.management.AddField(NewDlnLayer,DlnOnParcelBorder,"TEXT",field_length=1)

#Calculating values into the fields

arcpy.management.CalculateField(NewDlnLayer,DlnChangedField,"'N'","PYTHON3")
arcpy.management.CalculateField(NewDlnLayer,DlnOnParcelBorder,"'N'","PYTHON3") #IT'S BEEN FAILING HERE

Thank you,

Mike

 

Hayden Welch

I'd just use UpdateCursor objects for this task:

import arcpy

NewDlnLayer = "path/to/your/layer"
DlnChangedField = "DlnChangedField"
DlnOnParcelBorder = "DlnOnParcelBorder"

fields = [
    [
        DlnOnParcelBorder, #field name
        "TEXT",            #field type
        1                  #field length
    ],
    [
        DlnOnParcelBorder,
        "TEXT",
        1
    ],
]
#adding the fields
arcpy.management.AddFields(NewDlnLayer, fields)

#Calculating values into the fields using UpdateCursor
with arcpy.da.UpdateCursor(NewDlnLayer, [DlnChangedField, DlnOnParcelBorder]) as cursor:
    for row in cursor:
        row = ['N', 'N']
        cursor.updateRow(row)

 

If you keep having issues, you could try using arcpy.da.Editor() context and checking the exceptions raised?