Getting the ContentType from an ItemAdding Event Handler

Inside an event handler for an ItemAdded event, getting the List Item’s ContentType is as easy as

var contentType = properties.ListItem.ContentType;

However, for ItemAdding, properties.ListItem is null.

Luckily, the ContentType name and Id are part of the properties.AfterProperties collection – the following will work:

SPList list = properties.List; 
string contentTypeName = properties.AfterProperties["ContentType"].ToString(); 
SPContentType contentType = list.ContentTypes[contentTypeName]; 
SPFieldCollection fields = contentType.Fields;

Between the AfterProperties field values and the content type field collection, you typically have all that you need... Just remember to not depend on properties.ListItem.