topic Re: Select Layer by Attribute using an expression failing in Python Questions

Select Layer by Attribute using an expression failing

DonnaRiebe — Tue, 15 Aug 2017 18:12:14 GMT

Greetings, I am writing some code that puts in an expression into a SelectLayerByAttribute statement and am running into a problem. I am generating a running sequence of numbers (closNum) that are made into text. (using an SDE geodatabase FYI)

closNum = "'" + '{:05d}'.format(i) + "'"

When I print that out it looks like closNum = '00000'

I generate an expression statement expression = '"' + ' LABEL = ' + "'" + closNum + "'"+ '"' which prints out as " LABEL = '00000'"

What I would like to do is put that into my layer selection query arcpy.SelectLayerByAttribute_management(closureLyr, "NEW_SELECTION", expression)

So when I run that, I get an invalid expression error, but if I run arcpy.SelectLayerByAttribute_management(closureLyr, "NEW_SELECTION", " LABEL = '00000'"), it works just fine.

Somehow I am missing something but I can't figure out what.

Any help would be awesome

Actual code below

import string, arcpy
from arcpy import env
arcpy.env.overwriteOutput = True

inFC = 'Database Connections/GISTLMD on DNRHLN6341 as TLMD_FMB_MGR - FMB_RoadInventory.sde/GISTLMD.TLMD_DO.FMB_RoadClosures'
closureLyr = 'closureLyr'
count = 1
arcpy.MakeFeatureLayer_management(inFC,closureLyr)

for i in range(0,10,1):
#  print '{:05d}'.format(i)
closNum = "'" + '{:05d}'.format(i) + "'"
expression = '"LABEL = ' + closNum + '"'

arcpy.AddMessage(expression)
arcpy.SelectLayerByAttribute_management(closureLyr, "NEW_SELECTION", expression)
# arcpy.SelectLayerByAttribute_management(closureLyr, "NEW_SELECTION", "LABEL = '00000'")
result = arcpy.GetCount_management(closureLyr)
cnt = int(result.getOutput(0))
if cnt == 0:
  arcpy.AddMessage(expression + ' is missing')
  count = count + 1
#count = count + 1
if count == 5 :
  break

Donna

Re: Select Layer by Attribute using an expression failing

MitchHolley1 — Tue, 15 Aug 2017 19:24:27 GMT

Is the overall goal to simply count the instances of a certain value in a field? If so, I would just use a search cursor to count the values.

Re: Select Layer by Attribute using an expression failing

DonnaRiebe — Tue, 15 Aug 2017 19:27:42 GMT

I am just trying to flag gaps in the sequence so when I get new records I can fill in the gaps.

Re: Select Layer by Attribute using an expression failing

MitchHolley1 — Tue, 15 Aug 2017 19:33:26 GMT

So, if a closNum is not 00000, 11111, 22222, etc... than it needs to be updated?

Re: Select Layer by Attribute using an expression failing

DonnaRiebe — Wed, 16 Aug 2017 14:29:33 GMT

Yes, I then equipped with a list of labels that are aren't currently being used, as field folk add records, I can add a unique label to the record.

Re: Select Layer by Attribute using an expression failing

DonnaRiebe — Wed, 16 Aug 2017 14:33:33 GMT

I finally figured out what the problem was, the expression statement wasn't formatted correctly.

original - expression = '"LABEL = ' + closNum + '"' since the orginal closNum variable had the single quotes already in it.

revised (after I removed the single quotes from the closNum variable) - expression ="Label = \' " + closNum + "\'"

Thanks

Donna Riebe

Montana DNRC OIT/GIS