c# - LINQ to Entitiesは、メソッド'System.String ToBase64String（Byte []）'メソッドを認識しません。

Question

LINQ to Entitiesは、メソッド'System.String ToBase64String（Byte []）'メソッドを認識せず、このメソッドをストア式に変換できません。

 var activityList = (from item in committeeMemberList
                let committee = db.Committee.FirstOrDefault(x => x.Committee_Id == item.Committee_Id)
                let contact = db.Contacts.FirstOrDefault(x => x.Contact_Id == item.Contact_Id)
                select new Activity
                {
                   Id = Convert.ToBase64String(item.Committee_Member_SPE_Id), 
                   Name = committee.Committee_Name, 
                   ...
                   ...

                  }).ToList();

Answer 1

元のステートメントが匿名オブジェクトのリストを返すようにLINQを変更し、そのリストで選択してToBase64String関数を使用します。

var activityList = 
            (from item in
                (from member in committeeMemberList
                let committee = db.Committee.FirstOrDefault(x => x.Committee_Id == item.Committee_Id)
                let contact = db.Contacts.FirstOrDefault(x => x.Contact_Id == item.Contact_Id)
                select new
                {
                   Id = member.Committee_Member_SPE_Id, 
                   Name = committee.Committee_Name, 
                   ...
                   ...
                 }).ToList())
            select new Activity
            {
               Id = Convert.ToBase64String(item.Id), 
               Name = committee.Committee_Name, 
               ...
               ...

            }).ToList();