Linq列表到逗号的字符串

Question

我有这段代码。

var userListResult = from user in userList 
          from role in user.AspNetUsers.AspNetRoles 
          where role.Id == ((int)model.Roles).ToString() 
          select new UserManageViewModel.UserViewModel() 
          { 
           Id = user.UserId, 
           Email = user.AspNetUsers.Email, 
           Name = user.FirstName + " " + user.LastName, 
           IsAdviser = user.AspNetUsers.AspNetRoles.AsQueryable().Any(r => r.Id == ((int)eCareRoles.Adviser).ToString()), 
           IsAdmin = user.AspNetUsers.AspNetRoles.AsQueryable().Any(r => r.Id == ((int)eCareRoles.Admin).ToString()), 
           Company = user.UserCompanies != null ? user.UserCompanies.Name : String.Empty, 
           Role = model.Roles, 
           ListIfRoles = user.AspNetUsers.AspNetRoles.Select(x => x.Name).Aggregate((i, j) => i + "," + j) 

          }; 

我需要用逗号获得ListIfRoles字符串。但我总是得到错误 “LINQ to Entities does not recognized the method'System.String Aggregate [String]（System.Collections.Generic.IEnumerable 1[System.String], System.Func 3 [System.String，System.String，System.String]）''方法，并且这种方法不能转换成商店表达式。“

我试过string.Join（“，”，列表），尝试转换为数组，然后加入或聚合 - 但它总是错误。

另外我试过这个`用户。

AspNetUsers.AspNetRoles.Select(x => x.Name).AsEnumerable().Aggregate((i, j) => i + "," + j) 

但错误再次。 请帮忙。

Answer 1

可以尝试，

String.join(",",user.AspNetUsers.AspNetRoles.Select(x => x.Name).ToArray())