How to update related tables in entity-framework?

Question

I have a table named Tour and another table name TourPlan. These tables are related like below;

Tour                            TourPlan
Id (PK,int,not null)            Id (PK, int, not null)
Title (nvarchar(100), null)     Title (nvarchar(100), null)
                                TourId (FK, int, not null)

The problem is to update TourPlan table with existing values.

This is my code for updating;

Tour tour = TourController.GetTourById(Int32.Parse("13"));
tour.TourPlan.Clear();
foreach (ListItem item in lbPlans.Items)
   {
     tour.TourPlan.Add(new TourPlan() { Title = item.Text });
   }

And this is my update method;

public static int UpdateTour(Tour tour)
{
   using (var context = new aisatourismEntities())
     {
        Tour tUpd = context.Tour.FirstOrDefault(t => t.Id == tour.Id);
          if (tUpd != null)
            {
                tUpd.Title = tour.Title;
                tUpd.TourPlan = tour.TourPlan;
            }
          return context.SaveChanges();
     }
 }

But it's not updating, it inserts plan twice. How can I solve this?

Kenneth · Accepted Answer · 2013-05-08 09:18:14Z

3

You would need to update the data of TourPlan instead of overwriting the instance:

public static int UpdateTour(Tour tour)
{
   using (var context = new aisatourismEntities())
     {
        Tour tUpd = context.Tour.FirstOrDefault(t => t.Id == tour.Id);
          if (tUpd != null)
            {
                tUpd.Title = tour.Title;
                tUpd.TourPlan.Id= tour.TourPlan.Id;
                tUpd.TourPlan.TourId= tour.TourPlan.TourId;
                tUpd.TourPlan.Title = tour.TourPlan.Title;
            }
          return context.SaveChanges();
     }
 }

This of course supposes that you already have an attached instance of TourPlan. If not, you need to attach it to the DbContext.

answered May 8, 2013 at 9:18

Kenneth

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4 Comments

Mehmet Ince Over a year ago

Tour has multiple TourPlan so there is 1 to n relationship between two tables.

Kenneth Over a year ago

so Tour.TourPlan is a collection? In that case you should loop over the collection and copy the values.

Mehmet Ince Over a year ago

Yes. It'is collection. But if user deletes a plan and adds another plan in update, how would this be achieved?

Kenneth Over a year ago

You would need to synchronize it with the DbContext. To do this you need to attach it to the context. You can check this article for more information: msdn.microsoft.com/en-us/data/jj592676.aspx

sadovecki · Accepted Answer · 2015-04-23 09:39:58Z

1

This is how your method for updating TourPlan should look like:

    public static void UpdateTour(Tour tour, TourPlan tourPlan)
    {
        using (var context = new aisatourismEntities())
        {
            context.Tours.Attach(tour);

            context.Entity(tourPlan).Property(plan => plan.Title).IsModified = true;

            context.SaveChanges();
        }
    }

The second parameter of the method has to be already "prepared" TourPlan.

answered Apr 23, 2015 at 9:39

sadovecki

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