LINQ to Entities无法识别方法'System.String ToBase64String(Byte [])'方法， [英] LINQ to Entities does not recognize the method 'System.String ToBase64String(Byte[])' method,

问题描述

LINQ to Entities无法识别方法'System.String ToBase64String(Byte [])'方法，并且该方法无法转换为商店表达式.

LINQ to Entities does not recognize the method 'System.String ToBase64String(Byte[])' method, and this method cannot be translated into a store expression.

 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();

推荐答案

更改LINQ，以使原始语句返回一个匿名对象列表，然后在该列表中选择并使用ToBase64String函数:

Change your LINQ so that your original statement returns a list of anonymous objects, and then select on THAT list and use the ToBase64String function:

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();

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