Invalid Expression error on SelectLayerByAttribute

CharlesGeiger — Tue, 13 Nov 2018 20:01:44 GMT

My Python script uses two feature classes in a file geodatabase in ArcGIS Pro. I select several polygons from the Parcels fc and start the script. The script copies the polygons to the Neighborhoods fc, merges them into one polygon (using Dissolve) and should copy the script parameter entries into several fields of the new Neighborhoods polygon. I have tried many variations on the syntax for the "where clause" in the ArcPy SelectLayerByAttribute function, but always get an Invalid Expression failure on line 41:
arcpy.SelectLayerByAttribute_management (fc_out, "NEW_SELECTION", whereclause)

Any help would be greatly appreciated.

Here is the code:

# Python Script

# This script copies polygons from the Lancaster County Parcels feature

# class into the Neighborhoods feature class and processes them into a

# single neighborhood, complete with identifying attributes.

import arcpy

# Set the current workspace

from arcpy import env

env.workspace = "CURRENT"

import datetime

# Read the input parameter values:

# 0: Neighborhood Name: NbhdName

# 1: Plan Number part 1: PlanNum1

# 2: Plan Number part 2: PlanNum2

# 3: Plan Density: PlanDensity

# 4: Plan Date: PlanDate

nbhdName = arcpy.GetParameterAsText(0)

planNum1 = arcpy.GetParameterAsText(1)

planNum2 = arcpy.GetParameterAsText(2)

planNum = planNum1[0] + '-' + planNum1[-3:] + '-' + planNum2[-3:]

planDensity = float(arcpy.GetParameterAsText(3))

temp = arcpy.GetParameterAsText(4)

tempList = temp.split('/')

planDate = datetime.date(int(tempList[2]),int(tempList[0]),int(tempList[1]))

planYear = int(temp[-4:]) # extract the year from the date

# Copy the currently selected features in the parcels layer

fc_in = "Parcels_2016"

fc_tempin = "in_memory/Neighborhoods_in"

fc_tempout = "in_memory/Neighborhoods_out"

fc_out = "Neighborhoods_2016"

arcpy.CopyFeatures_management(fc_in, fc_tempin)

# Merge the copied parcels before adding to Neighborhoods fc

arcpy.Dissolve_management(fc_tempin, fc_tempout)

schema_type = "NO_TEST"

arcpy.Append_management(fc_tempout, fc_out, schema_type)

arcpy.SelectLayerByAttribute_management (fc_in, "CLEAR_SELECTION")

whereclause = '"Neighborhoods_2016.NBHD_NAME" = "NEW NBHD"'

arcpy.SelectLayerByAttribute_management (fc_out, "NEW_SELECTION", whereclause)

# result = arcpy.GetCount_management(fc_out)

fields = ["NBHD_NAME", "SUBPLAN", "DENSITY_Plan", "SubPlanDate", "SubPlanYear"]

# Create update cursor for feature class

with arcpy.da.UpdateCursor(fc_out, fields) as cursor:

for row in cursor: # DOES NOT execute on only the new neighborhood

row[0] = nbhdName.Title()

row[1] = planNum

row[2] = planDensity

row[3] = planDate

row[4] = planYear

cursor.updateRow(row)

Re: Invalid Expression error on SelectLayerByAttribute

JoshuaBixby — Tue, 13 Nov 2018 20:31:29 GMT

I am not sure if this is your only problem, but you need to wrap strings in single quotes, it is covered in the Building a query expression—Help | ArcGIS Desktop documentation. Try:

whereclause = "Neighborhoods_2016.NBHD_NAME = 'NEW NBHD'"‍

Re: Invalid Expression error on SelectLayerByAttribute

CharlesGeiger — Tue, 13 Nov 2018 20:48:03 GMT

Thank you, you got it in one. I had to change one other bit of code:
row[0] = nbhdName.Title()

became

row[0] = nbhdName.title()

Everything works now. Thank you!

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Invalid Expression error on SelectLayerByAttribute

Re: Invalid Expression error on SelectLayerByAttribute

Re: Invalid Expression error on SelectLayerByAttribute