topic Re: Add Field not working for multiple fields in Python Questions

Add Field not working for multiple fields

ThejaPutta — Fri, 10 Dec 2021 23:38:08 GMT

Hi,

I wrote a few lines of Python code to add a set of fields if they are not already present in a feature layer. Here is my code.

# Import modules
import arcpy

input_table = "myFeatureLayer"

# Input fields to create if they are not present in the feature layer
input_fields = ["a", "b", "c", "d", "e", "f", "g"]
# Field type
attr_type = "SHORT"

for field in input_fields:
     if len(arcpy.ListFields(input_table, wild_card=field)) == 0:
          arcpy.AddField_management(input_table, field_name = field, field_type = attr_type)

Sometimes it runs through the first 3 fields on the list before raising an error and sometimes it only goes through 1 or 2 fields. There are couple of times when the whole code ran without issue and created the entire list of fields.

This is the error I get:

Runtime error Traceback (most recent call last): File "<string>", line 13, in <module> File "c:\program files (x86)\arcgis\desktop10.3\arcpy\arcpy\management.py", line 3246, in AddField raise e ExecuteError: ERROR 999999: Error executing function. Failed to execute (AddField).

Any suggestions or thoughts on what the issue might be?

Thanks,

Theja

Re: Add Field not working for multiple fields

DanPatterson_Retired — Thu, 31 Mar 2016 16:32:30 GMT

you need to set your work environment for one thing, the layer name isn't sufficient, check the example

Add Field—Help | ArcGIS for Desktop

Re: Add Field not working for multiple fields

ThejaPutta — Thu, 31 Mar 2016 20:35:54 GMT

Thanks Dan!

That worked! I was using this in a tool earlier and the environment workspace that was set for the tool was different from the shapefile location.

I am still not very clear on why it works for the first one or two fields before raising an error.

Re: Add Field not working for multiple fields

DanPatterson_Retired — Thu, 31 Mar 2016 21:12:17 GMT

I think what you probably want to do is make sure that the field doesn't already exist. However, when you use ListFields, it returns a field object, from which you have to get its name and check to make sure it isn't in there.

I then would check the fields that you want to add ( ie your_fields in my example below) and see if they are 'in' the list of fields (via their name) that already are in there.

from here... ListFields—Help | ArcGIS for Desktop

featureclass = "c:/data/municipal.gdb/hospitals"

field_names = [f.name for f in arcpy.ListFields(featureclass)]

for fld in your_fields:

if fld in field_names:

print("this field {} exists already".format(fld))

else:

then proceed with adding the field as you have done