Calculate Field management throwing field name error

StephenKruzik — Wed, 10 Apr 2013 18:05:53 GMT

I have been racking my brain for over a week now and no matter how I format my code, the arcpy.CalculateField_management line just will not run for me.

The parts of the code for the operation are below.

arcpy.env.overwriteOutput = True env.workspce = "F:/GIS Data/Drivetesting.gdb" #mxd = arcpy.mapping.MapDocument("CURRENT") --used in the Arcpy environment #df = arcpy.mapping.ListDataFrames(mxd, "New Data Frame")  --used in the Arcpy environment Field = "PCode1" FC = "F:/GIS Data/Drivetesting.gdb/Carrier/Phone" MyField = Myfield = arcpy.ListFields(FC)[24] arcpy.MakeFeatureLayer_management(FC,"FC_lyr") ---------> tons of geoprocessing going on right here, but not included as not relevant to question (and saves space!)     mylist = []     # Iterate through the rows in the cursor       for item in Scursor:         a = (item.Frequency, item.PCode1,)         mylist.append(a)              mylist.sort()     mylist.reverse()     del mylist[1:]     applist = [x[1] for x in mylist]     applist.append(CellIDs.UNIQUE_ID)     applist.append(CellIDs.CellID)     print applist     PCode1 = str(applist[0])     PCode2 = str(applist[1])     PCode3 = str(applist[2])     Unitname = str(applist[3])     Columnname = '"Cellname1"'     print Cellname     print MyField.name          arcpy.SelectLayerByAttribute_management("FC_lyr","SUBSET_SELECTION",' "PN1" = ' + PCode1 + " or \"PN1\" = " + PCode2 + " or \"PN1\" = " + PCode3)     arcpy.CalculateField_management("FC_lyr",Columnname,Unitname)

It throws

ERROR 000728: Field "Cellname1" does not exist within table Failed to execute (CalculateField).

I've tried writing out Cellname1, I've tried getting it through arcpy.listfields. I've tried single quotes, double quotes, quoting the quotes...you name it; I think I've tried it. If anyone has any idea why this is happening, I would greatly appreciate some assistance as I am at my wits end here. I know the field name exists as the 'print MyField.name' is derived from the listfields function, and gives me "Cellname1" as my result. PLEASE HELP!

Re: Calculate Field management throwing field name error

JakeSkinner — Wed, 10 Apr 2013 18:40:32 GMT

Hi Stephen,

Syntax for the Calculate Field tool can be tricky. Change your two variables to the following:

Columnname= "Cellname1" Unitname = '"' + str(applist[3]) + '"'

The expression needs to have quotes at the start and end, even if the variable is a string.

Re: Calculate Field management throwing field name error

StephenKruzik — Wed, 10 Apr 2013 19:03:07 GMT

that did the trick.

thanks so much!!

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Calculate Field management throwing field name error

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