title: DynamoDB | How to ADD a boolean value to existing object
body: <p>I'm trying to <code>ADD</code> a boolean value to an existing DyanmoDB document. 
  I use the DocumentClient (js sdk). </p>
  
  <p>Please consider the following code: </p>
  
  <pre><code>let _documentClient = new AWS.DynamoDB.DocumentClient();
  let updateExpression = {
            TableName: 'some_table',
            Key: {'project_id': 1234},
            UpdateExpression: 'ADD #completed :completed',
            ExpressionAttributeNames : {
              '#completed' : 'completed'
            },
            ExpressionAttributeValues: {
              ':completed': false /* changing to non-boolean value works */
            }
          };
   _documentClient.update(updateExpression, (err, params) =&gt; {
      if (err) {
          console.log(err);
          return
      }
      console.log('done deal');
   });
  </code></pre>
  
  <p>Running above code results in the following error: </p>
  
  <pre><code>Incorrect operand type for operator or function; operator: ADD, operand type: BOOLEAN
  </code></pre>
  
  <p>Changing <code>:completed</code> to equal a non-boolean value works. </p>
  
  <p><strong>Question:</strong> How can I add a boolean value to an existing object using DocumentClient? </p>