An example of using the UpdateFormPost method in Contensis R8.2

forms-updateformpostmethod.cshtml

protected override HttpResponseMessage Post(NameValueCollection formValues)
        
        {
                // do something useful with the post
	      
	        formValues["Hidden Field"] = "New Value";
	        formValues["Transaction Id"] = GetTransactionId();
	        UpdateFormPost(formValues);
	        
	        // return relevant response to user
	        
                
        }