AWS IoT Core Rule for uplink_message rx_metadata array

I am transferring data from AWS IoT Core using a rule into DynamoDB, which works for everything except the rx_metadata from TTN since it is in an array.

I think the below is correct syntax, but it does not work.

uplink_message.rx_metadata[0].rssi as rssi
FROM ‘lorawan/+/uplink’

Any suggestions?

I found a solution.
get(uplink_message.rx_metadata,‘0’).rssi AS rssi