Empty values posted as "null"

[wallytax]

Is it true that empty values in a form are posted as "null"? Is there another way to avoid this (like sending an empty string)? Or should I check on the server if the value is "null"? I'm using a RestDataSource to send the data.

[dencel]

Check out http://www.smartclient.com/docs/10.0/a/b/c/go.html#attr..DataSource.sparseUpdates

[wallytax]

Although this works better for me, I don't think it changes the "null" problem. I have two questions:

1) Are empty values being submitted as "null"?
2) Is there a way to prevent fields from being submitted? I want to include "read-only" attributes in the data source that will not be send back if a form is submitted.