title: DynamoDB Scan, Error in ExpressionAttributeValues Unexpected Key NodeJS
body: <p>I'm trying to do a Scan to my DynamoDB table in NodeJS, but I'm having trouble with ExpressionAttributeValues because don't recognize the placeholder I defined in the filter expression. I pass as paremeter an object with the information I want, but sends me this error: </p>
  
  <p><em>"Unexpected Key ':Value' found in params.ExpressionAttributeValues['atributeValues'], "code":"Unexpected parameter"</em></p>
  
  <p>I don't know what's happening because if I put the content of the object as parameter it works perfectly so I'm stucked. </p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>function Consult(cb, Filter, Event){
    var filterExpression = Filter+"= :Value";
    if(typeof Event[Filter] == "string"){
      //This is the object I'm trying to pass as parameter
      var attributeValues = {
        ":Value" : {"S" : Event[Filter] }
      }
    }else {
      //This is the object I'm trying to pass as parameter
      var attributeValues = {
        ":Value" : {"N" : Event[Filter] }
      }
    }
    dynamodb.scan({
        TableName: tableName,
        FilterExpression: filterExpression,
        ExpressionAttributeValues:{ ":Value" : {"S" : Event[Filter] } } //This Works
        ExpressionAttributeValues:{ attributeValues } //This don't and I don't know why
    }, function(err, data){
        if(err){
            console.log(err);
            cb(err, null);
        } else {
            cb(null, data.Items);
        }
    });
  }</code></pre>
  </div>
  </div>
  </p>