Problem with AddJoin - "The Value Cannot Be A Table"

[Katie_Clark]

I am attempting to automate a process of exporting photos from a Survey123 geodatabase and give the output a custom filename, modified from the general script for exporting photos provided by Esri. Here is what I have so far. I am trying to join the Feature Layer, image_repeat table and image_repeat__ATTACH table before exporting the photos so that I can use fields that are in the feature class attribute table in the output file names. 

import arcpy
from arcpy import da
import os

featureTable = arcpy.GetParameterAsText(0) # the Feature layer
repeatTable = arcpy.GetParameterAsText(1) # the image_repeat table
attachTable = arcpy.GetParameterAsText(2) # the image_repeat__ATTACH table
fileLocation = arcpy.GetParameterAsText(3) # Output folder location for the photos

arcpy.AddJoin_management(repeatTable, "parentglobalid", featureTable, "globalid")
arcpy.AddJoin_management(repeatTable, "Nutrient_Bank_Monitoring.globalid", attachTable, "REL_GLOBALID")

with da.SearchCursor(repeatTable, ['DATA', 'ATT_NAME', 'ATTACHMENTID', 'site', 'plot']) as cursor:
    for item in cursor:
        attachment = item[0] # blob data type
        site = str(item[3])
        plotNum = str(item[4])
        filenum = "ATT" + str(item[2]) + "_" # i.e. ATT531_
        filename = site + "_Plot" + plotNum + "_" + filenum + str(item[1]) #i.e. miyagi_creek_Plot6_ATT531_plot_image-20200324-143302.jpg
        open(fileLocation + os.sep + filename, 'wb').write(attachment.tobytes())
        del item
        del filenum
        del filename
        del attachment‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

However, I get the following error message - "The value cannot be a table":

I have no problem doing the joins manually in ArcMap, so I'm unclear why it won't work in the script. Is it possible to do what I'm trying to do?

I am obviously still a python newbie, so many thanks in advance for any help or advice!

[MatthewWoodmansee]

Thank you both David and Katherine for your help.  I am posting my final code (with commented-out manual data tests and print statements) in case this will help anyone else.  I added in an "If" statement for the user to chose a project number (there will be lots of different projects using this one Collector application). I also used a lot of the code from another thread (I had forgotten how helpful list comprehensions are!: Is it possible to use a field for the filename of an attachment export? 

Here is my code - thanks again!

import arcpy

from arcpy import da

import os

inTable = arcpy.GetParameterAsText(0) # attachment table name (_ATTACH)

fileLocation = arcpy.GetParameterAsText(1) # folder of where the files will end up going

featureTable = arcpy.GetParameterAsText(2) # feature class holding the data we need.

ProjectNum = arcpy.GetParameterAsText(3) # project number user wants to export for

#featureTable = r"R:\Connections\GIS_Shared_Data.sde\GIS_shared_data.DBO.GlobalData_UTM\GIS_shared_data.DBO.AOC_testing"

featureFields = ['OBJECTID', 'ProjectNumber']

#use list comprehension to build a dictionary from SearchCursor

featureDict = {r[0]:(r[1:]) for r in arcpy.da.SearchCursor(featureTable, featureFields)}

#print featureDict

#related table, and the fields we want from that table

#inTable = r'R:\Connections\GIS_Shared_Data.sde\GIS_shared_data.DBO.AOC_testing__ATTACH'

TableFields = ['REL_OBJECTID', 'DATA', 'ATT_NAME']

#location of the folder where we place the attachments

#fileLocation = r'C:\Users\xxxxx\Desktop\TestingData\AttachmentTest'

#now run through the dictionary and create the files

with da.SearchCursor(inTable, TableFields) as cursor:

    for item in cursor:

        attachment = item[1]

        #item[0] is the unique ID (OBJECTID), take first item in Dictionary

        fileName1 = featureDict[item[0]][0]

        #print fileName1

        fileName2 = str(item[2]) #uses the "photo 1" text

        #print fileName2

        #add the ObjectID to the final version, then concat project number and attachment name

        fileNameFinal = str(item[0]) + "_" + str(fileName1) + "_" + fileName2

        #print fileNameFinal

        if fileName1 == ProjectNum:

            open(fileLocation + os.sep + fileNameFinal, 'wb').write(attachment.tobytes())

        del item

        del attachment

        del fileName1

        del fileName2

        del fileNameFinal

    del cursor

[DavidPike]

You can reference the data via a cursor through the dataset path itself, not even sure if it works on a layer. Also save the layer after the join then use that path in the cursor.

for fields input into the cursor you can pass in a list of field names as strings:

cursor_fields = ["Field1", "Field2", "Field3"]

with arcpy.da.cursor(path, cursor_fields) as cursor...

throw some print statements into the variables you're creating in the cursor, my guess is your final path is ending up a bit funky after concatenation, i'd use os.path.join instead.