A script to export attachments from ArcGIS Pro 3, pulling fields from either the attach table or the base table. Will create files based on the passed format string (expecting a string like "C:\Path\{CleanID}-{ATT_NAME}")

ExportAttachmentsFancy.py

from __future__ import print_function

import os.path
import string
import sys
from functools import lru_cache

import arcpy
from arcpy import da

_orig_stdout = sys.stdout
_orig_stderr = sys.stderr

log_file = open(r"C:\Users\JordanFox\OneDrive - Center for Watershed Protection\Desktop\fancylog.txt", "w", buffering=1)
print("Python Version: {}".format(sys.version), file=log_file)

sys.stdout = log_file
sys.stderr = log_file


base_table: str = arcpy.GetParameterAsText(0)
# Pass a filename format like `C:\dir\FILE_NAME-{CleanID}-{ATT_NAME}
format_str: str = arcpy.GetParameterAsText(1)

print("base_table: {}".format(base_table))
print("format_str: {}".format(format_str))

if not (base_table and format_str):
    arcpy.AddError("Expected two arguments: the base table, and a filename pattern")

if base_table.endswith("__ATTACH"):
    arcpy.AddWarning("Expected a base table as first parameter, does it really end in __ATTACH?")
attach_table = base_table + "__ATTACH"


def which_table(column: str) -> str:
    print("Trying to find column {}".format(column))
    for t in (attach_table, base_table):
        try:
            with da.SearchCursor(t, [column]) as cursor:
                item = next(iter(cursor))
                if item[0] is None or item[0] == "":
                    raise Exception("Got None")
            # Success
            table_name = "base" if t == base_table else "attach"
            print("Found column '{}' in {}".format(column, table_name))
            return table_name
        except Exception:
            print("No column '{}' in {}".format(column, t))
            pass
    raise Exception("Found no column '{}' on either table".format(column))


base_table_columns = []
attach_table_columns = []
format_args = set(
    [column for _, column, _, _ in string.Formatter().parse(format_str) if column is not None]
)
print("Format args: {}".format(format_args))
if not format_args:
    raise Exception("expected some format arguments (like `{SimpleID}`)")
for format_arg in format_args:
    if format_arg == "":
        raise "Expected all named format args! {FieldName}, not {}"
    if which_table(format_arg) == "base":
        base_table_columns.append(format_arg)
    else:
        attach_table_columns.append(format_arg)


def dict_from_columns(columns, row) -> dict:
    result = {}
    for i, column in enumerate(columns):
        result[column] = row[i]
    return result


@lru_cache(maxsize=1024)
def from_base_table(global_id) -> dict:
    if not base_table_columns:
        return {}
    print("Finding {} in base table".format(global_id))

    global_id = str(global_id)
    field = arcpy.AddFieldDelimiters(base_table, "GlobalID")

    where_clause = "{} = '{}'".format(field, global_id)

    with da.SearchCursor(base_table, base_table_columns, where_clause) as cursor:
        items = list(cursor)
        if len(items) != 1:
            raise Exception("Expected a single item in the base table with global id")
        item = items[0]

        return dict_from_columns(base_table_columns, item)


EXTRA_COLUMNS = ["ATT_NAME", 'DATA', "REL_GLOBALID"]
for column in EXTRA_COLUMNS:
    if column in attach_table_columns:
        attach_table_columns.remove(column)
with da.SearchCursor(attach_table, EXTRA_COLUMNS + attach_table_columns) as cursor:
    for item in cursor:
        att_name, data, rel_globalid = item[:3]
        if "." in att_name:
            period_pos = att_name.find(".")
            extension = att_name[period_pos:]
        else:
            # Take a guess
            extension = ".jpg"

        arg_values = dict_from_columns(attach_table_columns, item[3:])
        arg_values.update(from_base_table(rel_globalid))
        arg_values["ATT_NAME"] = att_name
        arg_values["DATA"] = data
        arg_values["REL_GLOBALID"] = rel_globalid

        filename = format_str.format(**arg_values)
        if "." not in filename:
            filename += extension

        directory = os.path.dirname(filename)
        if not os.path.exists(directory):
            print("{} does not exist yet, trying to create".format(directory))
            os.makedirs(directory, exist_ok=True)
        with open(filename, "wb") as f:
            f.write(data.tobytes())

        print("Wrote {}", filename)
        del data
        del item

sys.stdout = _orig_stdout
sys.stderr = _orig_stderr
log_file.flush()
del log_file