為什么自動映射器會拋出無法在linq中構造復雜型別的例外？[復制]

我創建了一個自動映射器

CreateMap<Records_Log, Records_LogDto>()
                .ForMember(dest => dest.UserName, opt =>
                {
                    opt.ResolveUsing(d => d.User.UserName);
                });

記錄_日志

public class Records_Log
    {
        public int Id { get; set; }
        public string Table_name { get; set; }



        [ForeignKey("Records")]
        public int RecordsId { get; set; }
        public Records Records { get; set; }
        public  int RecordId { get; set;  }
        public string OldValue { get; set; }
        public string NewValue { get; set; }

        [ForeignKey("User")]
        public string UserId { get; set; }
        public ApplicationUser User { get; set; }

        public DateTime ChangeDate { get; set; }

        public string Action { get; set; }


    }

Records_LogDto

public class Records_LogDto
    {

        public int Id { get; set; }
        public string Table_name { get; set; }

        public int RecordsId { get; set; }
        public Records Records { get; set; }

        public int RecordId { get; set; }
        public string OldValue { get; set; }
        public string NewValue { get; set; }

        public string UserId { get; set; }

        public string UserName { get; set; }

        public string Action { get; set; }

        public DateTime ChangeDate { get; set; }
    }

記錄：

public class Records
    {
        public int Id { get; set; }

        public string SerialName { get; set; }

        public string RecordsName { get; set; }

        public string Url { get; set; }
        public string AttachmentPath { get; set; }
        public string ImagePath { get; set; }

        public string RecordsNameModified { get; set; }

        public bool isDeleted { get; set; }

        public bool isRead { get; set; }

        public bool IsHidden { get; set; }
        public bool MarkAsImportant { get; set; }
        public string ImportantComments { get; set; }

        public int subTypeID { get; set; }


        public virtual ICollection<Records_Rate> Records_Rate { get; set; }

    }

我的查詢

var query = (from st in db.Records_State
                         join sl in db.Records_Log
                         on st.Records.Id equals sl.RecordsId
                         where st.Records.isDeleted
                         && sl.Table_name == nameof(Records)
                         && sl.Action == "Deleted"
                         && sl.NewValue == "Top"
                         && (string.IsNullOrEmpty(recordsName) || sl.Records.RecordsName.Contains(recordsName)
                            || sl.Records.RecordsNameModified.Contains(recordsName))
                         && (fromDate == null || sl.ChangeDate >= fromDate)
                         && (toDate == null || sl.ChangeDate <= toDate)
                         orderby sl.ChangeDate descending
                         select new Records_Log { 
                             Records= st.Records, 
                             ChangeDate= sl.ChangeDate 
                         })
                         .AsQueryable();

   



query = from p in query
                group p by p.Records.Id
                into pGroup
                orderby pGroup.Key
                select pGroup.FirstOrDefault();

        var result = query.Skip((pageNumber - 1) * pageSize)
          .Take(pageSize)
          .OrderByDescending(st => st.Id);

        var dto = Mapper.Map<List<Records_LogDto>>(result);

現在在最后一行var dto = Mapper.Map<List<Records_LogDto>>(result); 它拋出例外：

錯誤映射型別。\r\n\r\n映射型別:\r\nDbQuery1 -> List1\r\nSystem.Data.Entity.Infrastructure.DbQuery1[[PortalBackEndAPI.Models.Records_Log, PortalBackEndAPI.Core, Version=1.0.0.0 , Culture=neutral, PublicKeyToken=null]] -> System.Collections.Generic.List1[[PortalBackEndAPI.Dto.Records_LogDto, PortalBackEndAPI, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]"}

和

無法在 LINQ to Entities 查詢中構造物體或復雜型別“PortalBackEndAPI.Models.Records_Log”

uj5u.com熱心網友回復：

您傳遞給 map 方法的物件仍然是型別 DBQuery，Automapper 沒有為其配置映射。錯誤代碼提示了這一點！您傳遞的物件不是 Records_Log 型別的原因是因為您還沒有讓它決議。

檢查您是否可以在 DBQuery 上呼叫 ToList 或 ToListAsync 方法，如下例所示。

var dto = Mapper.Map<List<Records_LogDto>>(result.ToList());
// Or
var dto = Mapper.Map<List<Records_LogDto>>(await result.ToListAsync());

其中一種方法（還有其他方法）將強制決議 DBQuery 并將其加載到串列中。

標籤：C＃ 实体框架 自动映射器

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