LINQ to Entities - Multiple Joins - Null Reference Exception on 'Select'

I am trying to convert a SQL query to a LINQ to entities query, but am having some problems with the LINQ select block.

Here is the SQL query which performs as expected:

SELECT distinct( p.PendingID,
        p.Description,
        p.Date,
        f.Status,
        u.UserName,
        m.MapID
    FROM    Pending p
    JOIN    Users u 
   ON p.UserID = u.UserID
    LEFT JOIN Forks f 
   ON p.PendingID = f.PendingID
    LEFT JOIN Maps m
      ON f.ForkID = m.ForkID
    ORDER BY p.Date DESC

Here is the LINQ to entities query as I have it thus far:

var pList = (from pending in pendingItems
// JOIN
from user in userList.Where(u => pending.UserID == u.UserID)
// LEFT OUTER JOIN
from fork in forkList.Where(f => pending.ID == f.PendingID)
.DefaultIfEmpty()
// LEFT OUTER JOIN
from map in mapList.Where(m => fork.ID == m.ForkID)
.DefaultIfEmpty()
orderby pending.Date descending
select ne开发者_运维问答w
{
 ItemID = pending.ID,                 // Guid
 Description = pending.Description,   // String
 Date = pending.Date,                 // DateTime
 Status = fork.Status,               // Int32 (*ERROR HERE*)
 UserName = user.UserName,            // String 
 MapID = map.ID                       // Guid (*ERROR HERE*)
})
.Distinct()
.ToList();

The LINQ query fails on either of the following 2 lines, which attempt to assign values retrieved from left outer join results. If the following lines are omitted, the LINQ query completes without errors:

Status = fork.Status,
MapID = map.ID

Why are those 2 property assignments failing within the LINQ query's select block?

The problem is that due to your outer joins, fork and map may be null. Of course when they're null, you can't access their properties. You may need something like this:

Status = (fork == null) ? null : fork.Status,
MapID = (map == null) ? null : map.ID