topic Re: arcpy.Exists working in interactive window but not stand-alone script in Python Questions

arcpy.Exists working in interactive window but not stand-alone script

AllisonBailey — Fri, 01 Sep 2017 18:25:34 GMT

I am having trouble with the arcpy.Exists() function in a script to check the existence of a table in a personal geodatabase. When I test in the ArcToolbox Python window, I get the correct result, True, for a table that exists. When I use the same commands in a stand-alone script, regardless of how I construct the path string, it always returns False for the table. I also tested just the geodatabase, and it returns True, so it is not having trouble finding the geodatabase itself.

Below is the code from the script. When I run from the interactive window, I just remove the print statement.

import arcpy

print arcpy.Exists("Y:/projects/dnr_svmp2016/db/SVMP_2000_2015_DB.v52_20170803/SVMP_DB_v5.2_20170803_AB.mdb/site_samples")
print arcpy.Exists("Y:\projects\dnr_svmp2016\db\SVMP_2000_2015_DB.v52_20170803\SVMP_DB_v5.2_20170803_AB.mdb\site_samples")
print arcpy.Exists("Y:\\projects\\dnr_svmp2016\\db\\SVMP_2000_2015_DB.v52_20170803\\SVMP_DB_v5.2_20170803_AB.mdb\\site_samples")
print arcpy.Exists("Y:/projects/dnr_svmp2016/db/SVMP_2000_2015_DB.v52_20170803/SVMP_DB_v5.2_20170803_AB.mdb")

This script returns:

False

True

Here is screenshot of the interactive window:

I'm hoping that the solution is something very obvious that I am just missing right now! Thanks for any help.

Re: arcpy.Exists working in interactive window but not stand-alone script

DanPatterson_Retired — Fri, 01 Sep 2017 18:31:03 GMT

Just a hunch... try a file geodatabase rather than a personal geodatabase... and one without periods in it and other extraneous characters

Re: arcpy.Exists working in interactive window but not stand-alone script

AllisonBailey — Fri, 01 Sep 2017 18:38:27 GMT

Thanks Dan,

I also had concerns about the funky path, but as I mentioned, the arcpy.Exists() work for the geodatabase itself, which implies to me that the path is not the problem.

Also, I am writing code for others to use, so I don't have control over their file-naming convention or the type of geodatabase they are using. If that is the problem, I will need to find a different way to code this check, but it would be nice to know why the Exists function is so inconsistent.

Re: arcpy.Exists working in interactive window but not stand-alone script

DanPatterson_Retired — Fri, 01 Sep 2017 18:46:12 GMT

If funky is the default... try 'raw encoding (little r'

r'Y:\projects\dnr_svmp2016\db\SVMP_2000_2015_DB.v52_20170803\SVMP_DB_v5.2_20170803_AB.mdb\site_samples'

Re: arcpy.Exists working in interactive window but not stand-alone script

AllisonBailey — Fri, 01 Sep 2017 18:50:38 GMT

Sadly, same result -- False when run in script, True when run from interactive window.

Re: arcpy.Exists working in interactive window but not stand-alone script

AllisonBailey — Fri, 01 Sep 2017 18:59:13 GMT

Looks like a couple similar (irreproducible) bugs in the past: Esri Support Search-Results

Re: arcpy.Exists working in interactive window but not stand-alone script

DanPatterson_Retired — Fri, 01 Sep 2017 19:00:26 GMT

Then try a shorter, cleaner path with the .mdb to rule out a path issue

Then lastly is the use of *.gdb

Then try a different file...

Beyond that you have ruled everything else out

Re: arcpy.Exists working in interactive window but not stand-alone script

JamesCrandall — Sat, 11 Dec 2021 17:44:36 GMT

I tend to agree that there is a need to move into FileGeodatabases rather than those personal GDB's. Other than that, you can try to join the path and feature class name together instead of raw strings.

Instead of

r'Y:\projects\dnr_svmp2016\db\SVMP_2000_2015_DB.v52_20170803\SVMP_DB_v5.2_20170803_AB.mdb\site_samples'‍

Try

import os

gdb = r'Y:\projects\dnr_svmp2016\db\SVMP_2000_2015_DB.v52_20170803\SVMP_DB_v5.2_20170803_AB.mdb'
featureclass_name = r'site_samples'
featureclass = os.path.join(gdb, featureclass_name)
if arcpy.Exists(featureclass):
   'do stuff‍‍‍‍‍‍‍

Re: arcpy.Exists working in interactive window but not stand-alone script

AllisonBailey — Fri, 01 Sep 2017 19:44:36 GMT

Thanks James and Dan. I used os.path.join in my original code, but was just testing with the raw strings to make it more explicit what was happening.

Turns out it does work correctly with tables in a file geodatabase, regardless of the "funkiness" of the path. I'm still bothered by the fact that the same code works correctly in the interactive window correctly, but not in my script.

My IDE is using C:\Python27\ArcGISx6410.4\python.exe to run the script, so that looks like the right version to me.

Guess I'll work with ListTables instead and check against the list.

Re: arcpy.Exists working in interactive window but not stand-alone script

JoshuaBixby — Fri, 01 Sep 2017 19:48:10 GMT

The path to your IDE answers the question. Personal geodatabases are not supported with 64-bit Background Geoprocessing, which is the Python distribution your IDE is using. When running from within ArcMap, it is likely executing in-process, which means it is using 32-bit ArcPy and hence works still with personal geodatabases.

Trying changing your IDE to point to the 32-bit Python distribution that comes with ArcMap.

Re: arcpy.Exists working in interactive window but not stand-alone script

AllisonBailey — Fri, 01 Sep 2017 20:01:12 GMT

Ah ha! Thank you Joshua! That solved it. Really helpful info.

So, that explains why similar code I wrote (using arcpy.Exists) for the Validator of the Toolbox worked and this code didn't.

I don't remember changing/updating the interpreter in PyCharm -- it may have happened when I upgraded recently without me realizing it.

Re: arcpy.Exists working in interactive window but not stand-alone script

DanPatterson_Retired — Sat, 02 Sep 2017 02:22:10 GMT

grief python interpreters... why doesn't everything move to Anaconda and python 3.x

Re: arcpy.Exists working in interactive window but not stand-alone script

JoshuaBixby — Sat, 02 Sep 2017 23:48:02 GMT

I firmly believe 10.6 will stay with Python 2.x, which opens the door to ArcMap never going to 3.x. Pro is getting closer, but we still have too many workflows that can't be migrated cleanly between ArcMap to Pro, thus slowing the adopting of Pro in the organization.

Re: arcpy.Exists working in interactive window but not stand-alone script

DanPatterson_Retired — Sat, 02 Sep 2017 23:50:05 GMT

Like Y2K ... I still have Cobol friends making a living

Python countdown

Re: arcpy.Exists working in interactive window but not stand-alone script

RebeccaStrauch__GISP — Sat, 11 Dec 2021 17:44:38 GMT

Totally unrelated to your question, but a tip that might help in future...

When I run from the interactive window, I just remove the print statement.

I use a small function in every script (actually, in a custom utils.py that I have many utils) that I can use for either the interactive window or a script, without having to change print to arcpy.AddMessage

import arcpy 

def myMsgs(message):
     arcpy.AddMessage(message)
     print(message)

myMsgs("my message here, with {0} formatiing if needed".format("fancy"))
‍‍‍‍‍‍‍

I have a version that will add the date/time to the message, but that takes a few more steps. This is handy if switching between, especially when developing/debugging. just an fyi.