更好地将条目添加到主db表和链接表中的方法

Question

以下所有解决方案的工作原理是，它在MeetingRoomRequest表中创建记录，并将相关的设施添加到MeetingRoomRequestAmenityLink表中。然而，它只是感觉有点笨重，所以我想知道是否有一个更好的解决方案（即不必创建2个上下文实例）使用MVC 3和实体框架？

请注意我已经在SQL Server和实体框架中建立了必要的关系（一对多）。

另请注意AmenityList是一个id的数组（例如[1,2,4]）

private readonly IDataRepository<MeetingRoomRequest> _meetingRoomRequestRepository = new DataRepository<MeetingRoomRequest>();
private readonly IDataRepository<MeetingRoomRequestAmenityLink> _meetingRoomRequestAmenityLinkRepository = new DataRepository<MeetingRoomRequestAmenityLink>();

var meetingRoomRequestToAdd = new MeetingRoomRequest
{
    User = meetingRoomRequestViewModel.User,
    UserEmail = meetingRoomRequestViewModel.UserEmail,
    Title = meetingRoomRequestViewModel.Title,
    Comments = meetingRoomRequestViewModel.Comments,
    StartDateTime = meetingRoomRequestViewModel.StartTime,
    EndDateTime = meetingRoomRequestViewModel.EndTime,
    RequestStatusID = (int)Enums.RequestStatus.New,
    AttendeeCount = meetingRoomRequestViewModel.AttendeeCount,
    AttendeeType = meetingRoomRequestViewModel.AttendeeType,
    OfficeID = meetingRoomRequestViewModel.OfficeId,
    LocationID = meetingRoomRequestViewModel.LocationId, 
};
_meetingRoomRequestRepository.Add(meetingRoomRequestToAdd);
_meetingRoomRequestRepository.SaveChanges();
var meetingRoomRequestAdded = meetingRoomRequestToAdd;

foreach (var item in meetingRoomRequestViewModel.AmenityList)
{
    var meetingRoomRequestAmenityLinkToAdd = new MeetingRoomRequestAmenityLink
    {
        AmenityID = item,
        MeetingRoomRequestID = meetingRoomRequestAdded.MeetingRoomRequestID
    };
    _meetingRoomRequestAmenityLinkRepository.Add(meetingRoomRequestAmenityLinkToAdd);
    _meetingRoomRequestAmenityLinkRepository.SaveChanges();
}

Answer 1

你的方式看起来是正确的，但是在处理请求的效率方面可以有一些改进。

1. 由于这些是子/父关系，因此您可以创建父实体，然后在父实体上调用保存更改之前将childern附加到foreach循环中。 EF将使用来自父级的主（或相关密钥）自动填充子对象上的外键值。
2. 您可以继续使用您的实体，而无需将其保存回变量。 EF的对象跟踪将继续在整个功能中跟踪这一情况。
3. 通过将保存更改移到foreach循环之外，您可以减少调用次数。我相信在最后一次调用时会发送相同数量的SQL，但是您可能会看到没有连接打开/关闭的增加。 EF
也可能有其他内置效率

守则

var meetingRoomRequestToAdd = new MeetingRoomRequest
        {
            User = meetingRoomRequestViewModel.User,
            UserEmail = meetingRoomRequestViewModel.UserEmail,
            Title = meetingRoomRequestViewModel.Title,
            Comments = meetingRoomRequestViewModel.Comments,
            StartDateTime = meetingRoomRequestViewModel.StartTime,
            EndDateTime = meetingRoomRequestViewModel.EndTime,
            RequestStatusID = (int)Enums.RequestStatus.New,
            AttendeeCount = meetingRoomRequestViewModel.AttendeeCount,
            AttendeeType = meetingRoomRequestViewModel.AttendeeType,
            OfficeID = meetingRoomRequestViewModel.OfficeId,
            LocationID = meetingRoomRequestViewModel.LocationId, 
        };
        _meetingRoomRequestRepository.Add(meetingRoomRequestToAdd);

        foreach (var item in meetingRoomRequestViewModel.AmenityList)
        {
            meetingRoomRequestToAdd.MeetingRoomRequestAmenityLinks.Add(new MeetingRoomRequestAmenityLink
            {
                AmenityID = item
            });
        }
        _meetingRoomRequestRepository.SaveChanges();