server_script_auto_increment.txt

if doc.customer_name:
    # Get the maximum custom_auto_field from existing customer records
    latest_custom_auto_field = frappe.db.sql("""
        SELECT MAX(CAST(SUBSTRING_INDEX(custom_auto_field, '-', -1) AS UNSIGNED)) 
        FROM `tabCustomer` 
        WHERE custom_auto_field IS NOT NULL
    """)[0][0] or 0
 
    # If no custom_auto_field is present, set it to 'CUST-00001'
    if latest_custom_auto_field is None:
        next_custom_auto_field = "CUST-00001"
    else:
        # Increment the latest custom_auto_field value by 1 for the current document
        next_custom_auto_field = "CUST-" + str(latest_custom_auto_field + 1).zfill(5)
 
    doc.custom_auto_field = next_custom_auto_field