Update expression for a list of maps in DynamoDB - amazon-dynamodb

Question

I have the following DynamoDB table:
{
record_id: Decimal(10),
...,
options: [ # This is a List of maps
{option_id: 1, counter: Decimal(0), ...},
{option_id: 2, counter: Decimal(0), ...},
],
...
}
Which consists of some items, with unique record_id and the target options list. That list contains maps. In those maps, there is an option_id attribute, and I would like to access the item in the options list whose option_id equals to some target my_option_id and increment its counter.
For example, for the above example, given my_record_id=10 and my_option_id=2, I would like to update the second option item, with option_id=2, and increment its counter by 1, so this {option_id: 2, counter: Decimal(0), ...} becomes {option_id: 2, counter: Decimal(1), ...}.
I am using Python and boto3, but I imagine the syntax here is specific to DynamoDB. Here is what I have so far:
response = table.update_item(
Key={
'record_id': my_record_id,
},
UpdateExpression='SET options.#s.counter = options.#s.counter + :val',
ExpressionAttributeNames={
"#s": my_option_id
},
ExpressionAttributeValues={
':val': Decimal(1)
},
ReturnValues="UPDATED_NEW"
)

Answer 1

It seems the easy fix was to make options a map instead of a list, and then make the option_id the key of that map. Then my code works as expected:
response = table.update_item(
Key={
'record_id': my_record_id,
},
UpdateExpression='SET options.#s.counter = options.#s.counter + :val',
ExpressionAttributeNames={
"#s": my_option_id
},
ExpressionAttributeValues={
':val': Decimal(1)
},
ReturnValues="UPDATED_NEW"
)