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

Question

Consider two classes.

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

    public string Message_Id { get; set; }

    internal Message Mess         


        

Answer 1

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()
                  .HasOne(c => c.Message)
                  .WithOne()
                  .HasForeignKey(c => c.MessageId)                           
  }
  

• Create new class FileConfiguration and calling it inside OnModelCreating:

  public class FileConfiguration : IEntityTypeConfiguration
  {
      public void Configure(EntityTypeBuilder 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(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());                                       
  }