Getting ItemUpdating Even Receiver to do the same thing as ItemAdding

Question

I have a library that allows multiple folder content types. I am grouping the folders by content type but I don't want the group heading to say Content Type: whatever. Instead, I created a hidden column Study Type and I have an ItemAdding event receiver set this field when an item is created. This works fine.

Now it occurred to me that the client may want to edit the folder and my event receiver must still set the proper fields to new values. Easy, I thought. I would just add an ItemUpdating event to my receiver have it execute the same code and all done. But this doesn't work. Below is my code.

    public override void ItemAdding(SPItemEventProperties properties)
   {
       base.ItemAdding(properties);

       execute(properties);

   }

   public override void ItemUpdating(SPItemEventProperties properties)
   {
       base.ItemUpdating(properties);
       execute(properties);
   }

   public void execute(SPItemEventProperties properties)
   {
       base.EventFiringEnabled = false;

       SPList objlist = properties.List;
       System.Diagnostics.Trace.WriteLine("list " + objlist);
       string contentTypeName;
       SPContentType contentType;
       //initiolise(properties);

       if (objlist.Title == "In-House Studies" || objlist.Title == "CRO Studies" || objlist.Title == "Studies by Collaborators")
       {
           string titleInternalName = objlist.Fields["Study Type"].InternalName;
           string inVivoInVitro = objlist.Fields["In-Vivo/In-Vitro Type"].InternalName;
           string temp;
           try
           {
               contentTypeName = properties.AfterProperties["ContentType"].ToString();
               contentType = objlist.ContentTypes[contentTypeName];

               try
               {
                   if (contentType.Name == "In-Vitro Experiment")
                   {
                       properties.AfterProperties[titleInternalName] = "A.In-Vitro Experiment";
                       temp = objlist.Fields["In-Vitro Type"].InternalName;
                       properties.AfterProperties[inVivoInVitro] = properties.AfterProperties[temp];
                   }
                   else if (contentType.Name == "In-Vivo Study")
                   {
                       properties.AfterProperties[titleInternalName] = "B.In-Vivo Study";
                       temp = objlist.Fields["In-Vivo Type"].InternalName;
                       properties.AfterProperties[inVivoInVitro] = properties.AfterProperties[temp];
                   }
                   else if (contentType.Name == "CRO Study")
                   {
                       properties.AfterProperties[titleInternalName] = "A.CRO Study";
                   }
                   else if (contentType.Name == "Generic Folder")
                   {
                       properties.AfterProperties[titleInternalName] = "C.Generic";
                   }
                   else
                   {
                       properties.AfterProperties[titleInternalName] = "D.Document";
                   }

               }
               catch (Exception)
               {
                   properties.AfterProperties[titleInternalName] = "D.Document";
               }
           }
           catch (NullReferenceException)
           {
               properties.AfterProperties[titleInternalName] = "D.Document";
           }
       }

       base.EventFiringEnabled = true;
   }

Now my understanding is the AfterProperties contain the new values for the item in an ItemUpdating event receiver, however

    contentTypeName = properties.AfterProperties["ContentType"].ToString();

fails with a null reference exception. Why doesn't my code work with an ItemUpdating event receiver?

Answer 1

Try

properties.ListItem.ContentType

Or try what Quinn said:

string ctid = properties.AfterProperties["ContentTypeId"].ToString();
properties.List.ContentTypes[ctid];

Answer 2

Thanks Steve, I guess I'll put my response as an answer, deviated from your response to my suggestion.

string ctid = properties.AfterProperties["ContentTypeId"].ToString();
properties.List.ContentTypes[ctid];

Answer 3

Check the intername of the column you are trying to get the data from. if you have changed the name of the column after creating the list, then try with the old name.

Use 'Title' if you have changed it.

Answer 4

Here's what I ended up doing to get a solution:

string beforecType = properties.BeforeProperties["ContentTypeId"].ToString()
    , aftercType = properties.AfterProperties["ContentTypeId"].ToString()
    , beforeCTypeName = null
    , afterCTypeName = null
    , baseCTypeName = mappingHandler.ActiveFields.SharepointContentTypeName;

foreach (SPContentType ct in properties.List.ContentTypes)
{
    // Contains is OK because there doesn't seem to be a way to break it this way, at least not without much much larger ID numbers
    if (beforecType != null && (ct.Id.ToString() == beforecType || ct.Id.ToString().Contains(beforecType)))
    {
        beforeCTypeName = ct.Name;
    }
    if (ct.Id.ToString() == aftercType || ct.Id.ToString().Contains(aftercType))
    {
        afterCTypeName = ct.Name;
    }
}

It's not as pretty as I'd like and potentially inefficient if you have just a TON of content types, but it works and it's still within ItemUpdating instead of one of the other events.

Answer 5

Steve and Quinn's responses are correct with a little modification as highlighted in bold.

string ctid = properties.AfterProperties["ContentTypeId"].ToString();
properties.List.ContentTypes[**new SPContentTypeId(ctid)**];