arcpy - Export Attachments for Arcgis Collector - Naming

I am using Arcgis Desktop 10.4.1 and Arcgis Collector.

I've followed the guide for exporting attachments as described on ESRI's webpage here: http://support.esri.com/technical-article/000011912

It works really well, but I want to change the filenames. I want each filename to have the name from a field from the shapefile, and then a suffix (like _1,_2,_3)

I did fiddle a bit with this line, trying to add field names and whatnot, but I didnt get it to work.

 filename = filenum + str(item[1])

Anyone able to point me in the right direction?

---

Script from link:

import arcpy
from arcpy import da
import os

inTable = arcpy.GetParameterAsText(0)
fileLocation = arcpy.GetParameterAsText(1)

with da.SearchCursor(inTable, ['DATA', 'ATT_NAME', 'ATTACHMENTID']) as cursor:

    for item in cursor:
        attachment = item[0]
        filenum = "ATT" + str(item[2]) + "_"
        filename = filenum + str(item[1])
        open(fileLocation + os.sep + filename, 'wb').write(attachment.tobytes())
        del item
        del filenum
        del filename
        del attachment

Answer

To create a filename based on a field value in your feature class (rather than in the attachment table which your script is based on) you will need to get a dictionary of ObjectID and associated value from your specified field in your feature class, then another dictionary to count usage (as the values are used and files output).

I've based the increments on the field value - If the value is MyFieldValue and the file is the 5th file to be output with that value, the filename will be MyFieldValue_5. If the next file is the first one called YourFieldValue it would output as YourFieldValue_1.

import arcpy, os
from collections import defaultdict

inFC = r'D:\GIS\SE\GISSE.gdb\FCWithAtt' # Feature Class 
inTable = r'D:\GIS\SE\GISSE.gdb\FCWithAtt__ATTACH' # Attachment table
fileLocation = r'D:\GIS\SE\TestOutput' # Output location 

# Get dictionary of ObjectID and associated field value

myFeatures = dict()
with arcpy.da.SearchCursor(inFC, ['OID@', 'TextField']) as cursor:
    for row in cursor:
        myFeatures[row[0]] = row[1]

# Create dictionary to count usage of the field value (to increment files)
valueUsage = defaultdict(int)

# Loop through attachments, incrementing field value usage, and using that
# increment value in the filename

with arcpy.da.SearchCursor(inTable, ['DATA', 'ATT_NAME', 'ATTACHMENTID', 'REL_OBJECTID']) as cursor:
    for row in cursor:
        if row[3] in myFeatures:
            attachment = row[0]
            fieldValue = myFeatures[row[3]] # Value of specified field in feature class
            valueUsage[fieldValue] += 1 # Increment value
            filename = "{0}_{1}".format(fieldValue, valueUsage[fieldValue]) # filename = FieldValue_1
            output = os.path.join(fileLocation, filename) # Create output filepath
            open(output, 'wb').write(attachment.tobytes()) # Output attachment to file

For example I created a point feature class with three features. Note the values in TextField

I attached some images to each feature, including 5 images attached to a single feature. See in the field REL_OBJECTID that there are five images attached to feature class record with OBJECTID = 3.

The above script output those seven attachments, incrementing numbers on the filenames based on the field value.