CODEWITHSUNDEEP
entity-frameworkasp.net-coreentity-framework-core.net-coreasp.net-core-1.0
Chatumbabub
Chatumbabub

Reputation: 1637

Equivalent for .HasOptional in Entity Framework Core 1 (EF7)

Consider two classes.

public class File
{
    [Key]
    public string Id { get; set; }

    public string Message_Id { get; set; }

    internal Message Message { get; set; }
}

public class Message 
{
    [Key]
    public string Id { get; set; }       
}

In EF6, for N : 1..0 relation there was this fluent API.

modelBuilder.Entity<File>()
            .HasOptional(e => e.Message ).WithMany().HasForeignKey(e => e.Message_Id);

What is equivalent in Entiity Framework Core 1?

Thank you

Upvotes: 78

Views: 66321

Answers (3)

pkExec
pkExec

Reputation: 2066

To add to the accepted answer, if your property can't be configured as nullable (for example, if you are dealing with a split-table scenario, where the property is the primary key), adding IsRequired(false), will make the join optional (LEFT).

Like this:

modelBuilder.Entity<File>()
    .HasOne(s => s.Message)
    .WithMany()
    .HasForeignKey(e => e.Message_Id)
    .IsRequired(false)

Upvotes: 17

Sina Lotfi
Sina Lotfi

Reputation: 3284

In EF Core you can use two ways for relating two tables:

  • Inside OnModelCreating:

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

    modelBuilder.Entity<File>()
                .HasOne(c => c.Message)
                .WithOne()
                .HasForeignKey(c => c.MessageId)                           
}

  • Create new class FileConfiguration and calling it inside OnModelCreating:

    public class FileConfiguration : IEntityTypeConfiguration<File>
{
    public void Configure(EntityTypeBuilder<File> builder)
    {           
        builder.ToTable("File");            

        // Id
        builder.HasKey(c => c.Id);
        builder.Property(c => c.Id)
               .ValueGeneratedOnAdd();

        // Message
        builder.HasOne(c => c.Message)
               .WithOne(c => c.File)
               .HasForeignKey<Message>(c => c.MessageId)
               .OnDelete(DeleteBehavior.Restrict);
    }
}

    and inside OnModelCreating put below codes:

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

    modelBuilder.ApplyConfiguration(new FileConfiguration());                                       
}

Upvotes: 13

ocuenca
ocuenca

Reputation: 39326

You will not find an equivalent method in EF 7. By convention, a property whose CLR type can contain null will be configured as optional. So what decide if the relationship is optional or not is if the FK property is nullable or not respectively.

In summary, due to your Message_Id FK property is string, it already accepts null value, so if you use the following Fluent Api configuration:

modelBuilder.Entity<File>()
            .HasOne(s => s.Message)
            .WithMany()
            .HasForeignKey(e => e.Message_Id)

EF will configure your relationship as optional (or N : 0..1 as requested).

In case of your FK property is value type like int, you should declare it as nullable (int?).

Also I noticed now you have a navigation property with internal access modifier. You should always declare your entity properties as public.

Upvotes: 126

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