Question

Hi all the below solution works in that it creates a record in the MeetingRoomRequest table and also adds the associated amenities to that request into the MeetingRoomRequestAmenityLink table. However it just feels a bit clunky, so I was wondering if there is a nicer solution out there (i.e. not having to create 2 context instances) using MVC 3 and Entity Framework??

Please note i’ve set up the necessary relationships (one to many) in SQL Server and Entity Framework.

Also please note AmenityList is an array of id’s (e.g. [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

The way you are going about it looks right, but there are some improvements that could be made in efficiency of processing the request.

1. Since these are a child/parent relationship, you can create the parent entity and then attached the childern in the foreach loop before you call save changes on the parent entity. EF will automatically populate the foreign key value on the child object with the primary (or associated key) from the parent.
2. You can continue to use your Entity without having to save it back out to a variable. EF’s object tracking will continue to track this throughout your function.
3. By moving the savechanges outside of the foreach loop, you are reducing the number of calls. I believe the same amount of SQL will be sent on the one final call, but you may see increases of not having the connection open/close. There may be other built in efficiencies as well from EF

The Code

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();