updateItem'Expected'检查字符串集中的一个值

Question

I am trying to do a conditional updateItem call using php SDK2, but having trouble figuring out how to check for only a single value within a string set.

For Exmple: I have a string set in dynamoDB:

{"a","b","c"}

I want to do an updatedItem call, and delete one of those values, but error out if the value doesn't exist. So, if I attempted to remove "d" from the above set, I want dynamoDB to throw an error, not just silently ignore the fact that "d" doesn't exist in my string set.

I've tried:

    'Expected' => array(
        myAttribute => array(
            'Exists' => true,
            'Value' => array(Type::STRING_SET => array("d"))
        )
     )

This fails, however, even if the value was, for example, "a". I think the reason is that dynamoDB thinks I want it to validate the entire set, not just one value in it.

Is there a way to do a conditional put and verify just a single value within the set?

I can do a getItem call, grab the string set as an array and do my own checking, but I'd love to do it all in one call if possible.

Thanks in advance

Answer 1

Looking at the UpdateItem seems to indicate that DynamoDB looks at the value as a whole, and that you cannot have a condition based on a value within a set.

If you want a solid confirmation about whether or not you can do this or if you want to make a feature request for it, I would post on the official DynamoDB forum.