Bulk Insert Attachments

• Create a bulk_insert instance.

• Pass the Document ID to the instance's attachments_for method.

• To add an attachment, call the store method.
  Pass it the attachment's name, stream, and type (optional).
  store can be called repeatedly, as many times as needed.

• Note:
  If an attachment with the specified name already exists on the document,
  the bulk insert operation will overwrite it.

In this example, we attach a file to all User documents that match a query.

# Choose user profiles for which to attach a file
with store.open_session() as session:
    user_ids = [
        session.advanced.get_document_id(user)
        for user in list(session.query(object_type=User).where_less_than("Age", 30))
    ]

# Prepare content to attach
bytes_to_attach = b"some contents here"

# Create a BulkInsert instance
with store.bulk_insert() as bulk_insert:
    for user_id in user_ids:
        # Call 'attachments_for', pass the document ID for which to attach the file
        attachments_bulk_insert = bulk_insert.attachments_for(user_id)

        # Call 'store' to add the file to the BulkInsert instance
        # The data stored in bulk_insert will be streamed to the server in batches
        attachments_bulk_insert.store("AttachmentName", bytes_to_attach)