dynamodb fill empty cells with previous value


Hi I've been collecting data from IoT core and transfer it to aws dynamodb for storing the data. if the values didn't change the mqtt will receive an empty string were the cells remains empty. is their a way to fill the empty cells with their previous values? Or should i configure that on the mqtt part. Or can i remove the empty cells somehow?


asked 13 days ago22 views
2 Answers

Its not clear from your question, but I believe you are calling PutItem with only select attributes, as PutItem is a complete overwrite of your data, you are deleting other attributes which you wish to maintain.

PutItem docs.

To overcome that, you should use UpdateItem which will only update the attributed given in the payload. Furthermore, if the item does not exist it will act like a PutItem and write the new item.

UpdateItem docs.

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answered 13 days ago


I assume that you are using one of the AWS IoT Core DynamoDB actions in a rule. Both actions use PutItem hence the behavior you observe. As Leeroy mentions, UpdateItem should be used, but you will need to pass the message to a Lambda function first.

An alternative is to use a WHERE clause in the rule to only execute the rule if the string is not empty.


answered 13 days ago

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