连接具有相同ID的2列时出现NullReferenceException

Question

The situation is that i am joining 2 column with same ID to End up with a Single Column Table and my problem is some Info dont have Contact so this line (b => b.InfoID == a.ID) returns null or false and it shows NullReferenceException Error, Can someone help me with my problem in Linq??

This is what my Table show before

|     Name     |    Address   |     Cellphone    |     Email      | 
|     John     |     NY       |       n/a        |   johndoe@y.c  |
|     John     |     NY       |    123456781     |       n/a      |

And i want my output to be one liner combined

|     Name     |    Address   |     Cellphone    |     Email      | 
|     John     |     NY       |     123456781    |   johndoe@y.c  |

This is my Linq that shows the Joined table but when Info doesnt have Contact yet, It returns NullReferenceError

var an = (from a in db.Info  
              from b in db.Contact.Where(b => b.InfoID == a.ID && b.ContactTypeID == 56 && b.LogicalDelete == false).DefaultIfEmpty()
              from c in db.Contact.Where(c => c.InfoID == a.ID && c.ContactTypeID == 59 && c.LogicalDelete == false).DefaultIfEmpty()           
              where 
              select new
              {
                  a.ID,
                  a.LastName,
                  a.FirstName,
                  a.MiddleName,
                  Email = b.Values,
                  Cellphone = c.Values,
              }).ToList();

Answer 1

You should check if b or c object is null or not like this

   var an = (from a in db.Info  
          from b in db.Contact.Where(b => b.InfoID == a.ID && b.ContactTypeID == 56 && b.LogicalDelete == false).DefaultIfEmpty()
          from c in db.Contact.Where(c => c.InfoID == a.ID && c.ContactTypeID == 59 && c.LogicalDelete == false).DefaultIfEmpty()           
          where 
          select new
          {
              a.ID,
              a.LastName,
              a.FirstName,
              a.MiddleName,
              Email = b==null? "" : b.Values,
              Cellphone = c==null? "" : c.Values,
          }).ToList();

You are using DefaultIfEmpty method so it is possible that object b or c could be null.