Recently I threw some code together to add objects into an Azure table.  I used the class:

	[DataServiceKey("PartitionKey", "RowKey")]
	public class OrderMessage : TableServiceEntity
	{
		public DateTime OrderDate { get; set; }
		public string CustomerName { get; set; }
		public string CreditCard { get; set; }
		public int Quantity { get; set; }
		public decimal CostEach { get; set; }
	}

Upon adding the data to the table using:

	TableServiceContext tableContext = connection.TableClient.GetDataServiceContext();
	tableContext.AddObject(connection.OrderTableName, message);
	DataServiceResponse response = tableContext.SaveChangesWithRetries();

I received the error:

<?xml version="1.0" encoding="utf-8" standalone="yes"?>

<error xmlns="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">

<code>InvalidInput</code>

<message xml:lang="en-US">One of the request inputs is not valid.</message>

</error>

After wasting some time looking at help and Googling I was skimming across some documentation on tables and it happened to list the supported property types for Azure tables.  I knew that they had limited support but not till I looked at that list did it occur to me that I was using the unsupported datatype ‘decimal’.  Modifying the class so that CostEach was of type ‘double’ resolved my problem. 

It sure would be nice if the error was a little more explicit.  I’m sure that somewhere in the Azure code it knows what happened.  I also find it interesting that rather than returning information in the DataServiceResponse it throws an exception.  I don’t see this ability to throw exceptions in the documentation and in fact the documentation says that the return value is:

A DataServiceResponse that contains status, headers, and errors that result from the call to SaveChanges.

On well I guess somebody kinda forgot to update their XML comments on the method with:

/// <exception cref="System.Data.Services.Client.DataServiceClientException">A stealth exception that we won't tell anybody about</exception>

More than once I’ve seen a reminder on blogs to make sure you only use the supported data types on your table entities.   Here’s another reminder for you and *bonk* me!