Entity Framework 7 AddRange() Not Adding Foreign Entities

Question

Entity Framework 7 AddRange() Not Adding Foreign Entities

c# entity-framework entity-framework-core

Question

I've been using EF Code First for awhile but this is my first time with EF7.

I have the following Model classes where Venue has a one-to-many relationship to Show:

public class Show
{
    public int Id { get; set; }
    public Venue Venue { get; set; }
    //...
}

public class Venue
{
    public int Id { get; set; }
    public string Name {get; set; }
    //...
    public List<Show> Shows { get; set; }
}

I set up the DBContext like this:

public class NettlesContext : DbContext
{
    public DbSet<Show> Shows { get; set; }
    public DbSet<Venue> Venues { get; set; } 

    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);

        new ShowConfiguration(builder.Entity<Show>());
        new ImageConfiguration(builder.Entity<Image>());
    }
}

public class ShowConfiguration
{
    public ShowConfiguration(EntityTypeBuilder<Show> builder)
    {
        builder.Property(p => p.Id).IsRequired();
        builder.Property(p => p.Title).IsRequired();
    } 
}

public class VenueConfiguration
{
    public VenueConfiguration(EntityTypeBuilder<Venue> builder)
    {
        builder.Property(p => p.Id).IsRequired();
        builder.Property(p => p.Name).IsRequired();
    }
}

Then in some start up code I initialize the database like this:

    private static void AddShows(NettlesContext db)
    {
        var shows = new List<Show>()
        {
            new Show()
            {
                Title = "Portland Country Dance Community Contra Dance",
                Venue = new Venue()
                {
                    Name = "Fulton Community Center",
                },
            },
            new Show()
            {
                Title = "Portland Roadhouse Contra Dance",
                Venue = new Venue()
                {
                    Name = "Milwaukie Community Club",
                },
            },
        };

        db.Shows.AddRange(shows);
        db.SaveChanges();
    }

The Shows table is properly initialized except that the VenueId is null. The Venue table is entirely empty.

What's going on?

Kevin Johnsrude

Popular Answer

You need to update your model as this

public class Venue
{
  public int Id { get; set; }
  public string Name {get; set; }
  //...
  public List<Show> Shows { get; set; }
 }
public class Show
{
  public int Id { get; set; }
  public int VenueId { get; set; }
  [ForeignKey("VenueId")]
  public Venue Venue { get; set; }
  //...
}

ForegnKey attribute is used to define the foriegn key of the relation between two tables

Hady Allam

View more on Stack Overflow

natemcmaster · Accepted Answer · 1/9/2016 5:42:25 AM

There is a second argument to DbSet.Add.

Add(TEntity entity, GraphBehavior behavior = GraphBehavior.IncludeDependents)

Although the default is to IncludeDependents (aka children entities), EF7's behavior of Add() is not identifying Venue as a child of Show. In your OnModelCreating you need to specify the relationship between Venue and Show. See Relationships in the EF7 Docs.

Example:

modelBuilder.Entity<Venue>(entityBuilder =>
{
    entityBuilder
        .HasMany(v => v.Shows)
        .WithOne(s => s.Venue)
        .HasForeignKey(s => s.VenueId);
});

Even with this however, you will still need to call .Add on the new instances of Venue because Show is not a dependent (child) of Venue.

private static void AddShows(NettlesContext db)
{
    var fulton = new Venue()
            {
                Name = "Fulton Community Center",
            };
    var club = new Venue()
            {
                Name = "Milwaukie Community Club",
            };
    db.Venues.Add(fulton);
    db.Venues.Add(club);

    var shows = new List<Show>()
    {
        new Show()
        {
            Title = "Portland Country Dance Community Contra Dance",
            Venue = fulton,
        },
        new Show()
        {
            Title = "Portland Roadhouse Contra Dance",
            Venue = club
        },
    };
    context.Shows.AddRange(shows);
}

Worth noting: this behavior of .Add() has been a source of confusion in EF7 RC1 and its behavior may be changing in EF7 RC2. See https://github.com/aspnet/EntityFramework/pull/4132

Entity Framework 7 AddRange() Not Adding Foreign Entities

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