Amazon DynamoDB getting items as a string

Question

I am encountering difficulty in retrieving data from my table. I am using Amazon Dynamo DB and I have successfully populated my table. When I scan the table or use getItem, the returning information is of type AttributeValue. I have looked through the documentation and I can't find how you should process an AttributeValue to get it to become an int or string. The example code of scan from the Amazon Website has the information returned in a Dictionary object, but it is a dictionary with strings mapped to Attribute Values. Do you know of anyway to query a Dynamo DB table and store the result in something where strings are mapped to string or strings are mapped to integers?

Answer 1

Assuming you are using the AWS SDK for Java, objects of Class AttributeValue can be of type String, Number, StringSet, NumberSet and the class features respective getters/setters accordingly, e.g.:

• public String getN() - Numbers are positive or negative exact-value decimals and integers. A number can have up to 38 digits precision and can be between 10^-128 to 10^+126.
• public String getS() - Strings are Unicode with UTF-8 binary encoding. The maximum size is limited by the size of the primary key (1024 bytes as a range part of a key or 2048 bytes as a single part hash key) or the item size (64k).

Please note that the return value of getN() is still a string and must be converted by your Java string to number conversion method of choice accordingly. This implicit weak typing of the DynamoDB data types retrieval/submission based on String parameters only is a bit unfortunate and doesn't exactly ease developing, see e.g. my answer to Error in batchGetItem API in java for such an issue.

Good luck!