title: Update an attribute value to blank ("") in dynamodb
body: <p>How can one update an attribute value in DynamoDB table to ""?</p>
  
  <p>one option is to get the item into a document and then copy all the attributes into a new document except the attribute whose value is to be updated to "" and then call putitem, this would basically replace the whole item (as the hash key exists) and since I don't have the attribute anymore it would be deleted.</p>
  
  <p>Note: I could have simply done delete item but my requirement is to update more than one attribute value and one of these is blank.</p>
  
  <p>Please suggest me a better approach if any.</p>
  
  <p>Thanks in advance.</p>