Getting SPList object by Guid giving exception "List...does not exist at site with URL"

Question

I am trying to load a drop down list with the same items that a lookup field uses. I thought it would be relatively straightforward, but the line

SPList lookupList = lookupWeb.Lists[lookupField.LookupList];

Throws an exception despite the list with that ID existing in the SPWeb. (I checked both through the object model and SharePoint Manager)

        SPFieldLookup lookupField = targetLibrary.Fields["DocumentType"] as SPFieldLookup;
        using (SPWeb lookupWeb = SPContext.Current.Site.OpenWeb(lookupField.LookupWebId))
        {
            SPList lookupList = lookupWeb.Lists[lookupField.LookupList];
            foreach (SPListItem item in lookupList.Items)
            {
                ddlDocumentType.Items.Add(new ListItem(item["Title"].ToString(), item["ID"].ToString()));
            }
        }

List '{843fa16d-ec85-45c3-8d27-20d0241d41d6}' does not exist at site with URL

Is there something simple I am missing?

Answer 1

Highest voted answer doesn't even provide the right answer. Try doing this:

SPList lookupList = lookupWeb.Lists[new Guid(lookupField.LookupList)];

Instead of this:

SPList lookupList = lookupWeb.Lists[lookupField.LookupList];

Answer 2

So SPFieldLookup has an actual Guid for LookupWebId property and only a string for the LookupList property. So the line

SPList lookupList = lookupWeb.Lists[lookupField.LookupList];

Is using the string override which looks up the list name.

So the learning here, yet again, is do not expect the SharePoint object model to be consistent in any way.