title: How to get list of items from DynamoDB with HashKey while using HashKey+RangeKey combination?
body: <p>I have my table with UserId(hashkey)+id(Rangekey). they are only together unique as expected.</p>
  
  <pre><code>  [DynamoDBTable("Item")]
      public class Item
      {
          [DynamoDBHashKey]
  
          public string UserId { get; set; }
  
          [DynamoDBRangeKey]
  
          public string id { get; set; }
      }
  </code></pre>
  
  <p>now I want to get all the table items for a UserId. I tried as below using xamarin sdk loadasync function with parameter of an existing UserId.</p>
  
  <pre><code>          var client = new 
  Amazon.DynamoDBv2.AmazonDynamoDBClient(AWS.DynamoDBhelper.Credentials, 
      Amazon.RegionEndpoint.USEast1);
                          Amazon.DynamoDBv2.DataModel.DynamoDBContext context = new 
      Amazon.DynamoDBv2.DataModel.DynamoDBContext(client);
                          Items= await context.LoadAsync&lt;List&lt;Item&gt;&gt;("14354365");
  </code></pre>
  
  <p>But i get exception as below, it looks like It expects not list because it assumes there should be table with table with list. 
  How can I achieve this? 
  There is also QueryAsync function but I am not sure what is the difference between LoadAsync.</p>
  
  <pre><code>        ex = {System.InvalidOperationException: Must have one hash key defined
   for the table List`1
            at Amazon.DynamoDBv2.DataModel.DynamoDBContext.MakeKey (System.Object 
      hashKey, System.Object rangeKey,
       Amazon.DynamoDBv2.DataModel.ItemStorageConfig storageConfig, Amaz...
  </code></pre>