Entity Framework Debacle

Question

I am developing an MVC application which and I'm not clear on the ideal way to save these entities. What I am doing now works but is nasty to say the least.

My action method takes ViewModels and uses Automapper to map them to the related entities. My entities are Requestor, Order and OrderDetail.

Obviously all these calles to the SaveChanges method are wrong but I have been running into issues of new children being added instead of updated amongst other things.

Any help on how this code should look would really be appreciated.

Jason MacKenzie

 [HttpPost]
    public ActionResult Edit(FormCollection formValues, RequestorViewModel requestor, OrderViewModel order, List<OrderDetailViewModel> OrderDetails)
    {

        var query = from r in db.Requestors
                    where r.RequestorID == requestor.RequestorID
                    select r;
        var req = query.SingleOrDefault();

        var orderQuery = from o in db.Orders
                         where o.RequestorID == requestor.RequestorID
                         select o;
        var or = orderQuery.SingleOrDefault();


        List<OrderDetail> orDet = db.OrderDetails.Where(od => od.OrderID == or.OrderID).ToList();


        Mapper.CreateMap<RequestorViewModel, Requestor>();
        req = Mapper.Map<RequestorViewModel, Requestor>(requestor);

       Mapper.CreateMap<OrderViewModel, Order>();
       or = Mapper.Map<OrderViewModel, Order>(order);

       Mapper.CreateMap<OrderDetailViewModel, OrderDetail>();
       orDet = Mapper.Map<List<OrderDetailViewModel>, List<OrderDetail>>(OrderDetails);

       foreach (OrderDetail od in orDet)
       {
           db.OrderDetails.ApplyCurrentValues(od);
           db.SaveChanges();

       }

        db.Requestors.ApplyCurrentValues(req);
        db.SaveChanges();

        db.Orders.ApplyCurrentValues(or);
        db.SaveChanges();



        return View("Index");
    }

This can be helpful: http://stackoverflow.com/questions/3594515/how-to-update-an-entity-in-entity-framework-4-net/3594608#3594608 For working with relations also check this: http://stackoverflow.com/questions/3635071/update-relationships-when-saving-changes-of-ef4-poco-objects/3635326#3635326 — Ladislav Mrnka, Mar 16 '11 at 15:38

BZink · Accepted Answer · 2011-03-16T17:55:13.700

0

First you can clean up your queries quite a bit.

var req = (from r in db.Requestors
                where r.RequestorID == requestor.RequestorID
                select r).SingleOrDefault();

var or = (from o in db.Orders.Include("OrderDetails")
                     where o.RequestorID == requestor.RequestorID
                     select o).SingleOrDefault();

Take a look at how .Include works to map all your related data. It's very useful.

You should only need to call SaveChanges() once too.

edited Mar 16 '11 at 17:55

answered Mar 16 '11 at 16:41

BZink

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Note that .FirstOrDefault() is not identical semantics to .SingleOrDefault() – dthorpe Mar 16 '11 at 17:24
Right sorry. Used FirstOrDefault() out of habit. Edited my answer, thanks! – BZink Mar 16 '11 at 17:54
2

The cleanest syntax would be along the lines of `db.Requestors.SingleOrDefault(r => r.RequestorID == requestor.RequestorID)`. – Yakimych Mar 16 '11 at 18:12
Thank you very much for the responses. Very helpful and my code is much less painful to look at. – Jason MacKenzie Mar 16 '11 at 18:59

Entity Framework Debacle

1 Answers1