我对linq和 Entity Framework 非常陌生。我正在尝试解决以下问题无法解决的问题。产生的错误是“无法创建类型'Anonymous type'的常量值。在此上下文中仅支持原始类型或枚举类型。”

我已经尝试了许多不同的方法,但仍然收到与原始类型有关的错误。如果有人可以看一下下面的代码并希望指出它出了什么问题,我将不胜感激。

        public Entities.BikeData[] GetBikesWithExpiredSyncDeadline(int noOfDays) {

        using (OfficeEntities cxt = GetContext())
        using (ReportingEntities RepCxt = GetReportingContext()) {
            Data.Repository.Abstract.IBikeRepository BikeRepos = new Data.Repository.Concrete.BikeRepository();

            var details = (from sd in cxt.BikeDetails
                                        where sd.autoreminder == true
                                            && (sd.lastremindersent == null || sd.lastremindersent < EntityFunctions.AddDays(DateTime.UtcNow, noOfDays * -1))
                                            && (sd.emailaddress != null && sd.emailaddress.Trim() != "")
                                        select new {
                                            Serial = sd.Serial,
                                            EmailAddress = sd.emailaddress
                                        }).ToList();

            var resLst = (from r in RepCxt.RegisteredBikes
                          join d in details on r.Serial equals d.Serial
                          join cs in cxt.CompanySettings.ToList() on r.CompanyID equals cs.CompanyID
                          where (!r.lastupdate.HasValue || r.lastupdate < EntityFunctions.AddDays(DateTime.UtcNow, cs.AutoNotificationFrequency * -1))
                          select new Entities.BikeData {
                              ID = r.ID,
                              Name = r.Ship,
                              Serial = r.Serial,
                              LastUpdate = r.lastupdate,
                              DaysSinceLastSync = (r.lastupdate.HasValue? EntityFunctions.DiffDays(r.lastupdate.Value, DateTime.UtcNow).Value : -1),
                              EmailAddress = (d.EmailAddress == null ? string.Empty : (String.IsNullOrEmpty(d.EmailAddress) ? r.ShipEmailAddress : d.EmailAddress))
                          });

            return resLst.ToArray();
        }
    }

更新

现在,我通过创建 View 采用了另一种方法,因此不再需要在EF中进行跨上下文联接。我希望您可以在以下方面提供帮助。

当我运行objectQuery.ToTraceString()时,它为我提供了返回数据库中记录的有效SQL,但是EntityFramework中的resLst始终返回0。为什么会发生这种情况?
  var resLst = (from ls in cxt.BikeLastUpdates
                          where (!ls.lastupdate.HasValue || ls.lastupdate < EntityFunctions.AddDays(DateTime.UtcNow, ls.AutoNotificationFrequency * -1))
                          && (ls.autoreminder ==true)
                          && (ls.lastremindersent == null || ls.lastremindersent < EntityFunctions.AddDays(DateTime.UtcNow, 3 * -1))
                          && (ls.emailaddress !=null && ls.emailaddress.Trim() != "")
                          select new Entities.BikeData{
                              ID = (ls.ID ?? new Guid()),
                              Name = ls.Bike,
                              Serial = ls.Serial,
                              LastUpdate = ls.lastupdate,
                              EmailAddress = (String.IsNullOrEmpty(ls.emailaddress) ?  ls.ShipEmailAddress : ls.emailaddress)
                          });

            var objectQuery = resLst as ObjectQuery;

            return resLst.ToArray();

最佳答案

问题是对详细信息的ToList()调用。在EF中,如果该IEnumerable具有简单类型(例如int),则只能在Query中引用该IEnumerable。但是,您可以引用另一个IQueryable。因此,删除ToList()调用应该可以完成这项工作。

编辑:同样,您应该删除对ctx.CompanySettings的ToList()调用。

这将具有仅执行1个查询而不是2个查询的附加优点。如果将ToList()放到详细信息上,EF将生成类似以下内容的内容:

SELECT ...
FROM RegisteredBikes rb
JOIN (
    /* this is your "details" IQueryable */
    SELECT Serial, EmailAddress
    FROM BikeDetails
    WHERE ...
) bd
    ON rb.Serial = b.Serial
JOIN CompanySettings cs
    ON ...
WHERE ...

编辑:要跨上下文执行此操作,您需要将查询带入内存中(例如,通过调用AsEnumerable()并在其中执行相关的联接。如果联接充当过滤器,并且对于这些联接在SQL中发生很重要,请考虑使用Contains()。例如
var serials = details.Select(d => d.Serial);
var filtered = RepCtxt.RegisteredBikes.Where(r => details.Contains(r.Serial);

10-01 19:29
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