EF Core 1.x Customizations

ApplicationDbContext.cs

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
    public DbSet<OrderItem> Orders { get; set; }

    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options) { }

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

        // Customizations must go after base.OnModelCreating(builder)

        builder.Entity<ApplicationUser>(config =>
        {
            // Override nvarchar(max) with nvarchar(15)
            config.Property(u => u.PhoneNumber).HasMaxLength(15);

            // Make the default table name of AspNetUsers to Users
            config.ToTable("Users"); 
        });

        builder.Entity<OrderItem>(config =>
        {
            // Make the default column type datetime over datetime2 (for some reason).
            config.Property(o => o.DateTimeOrdered).HasColumnType("datetime");

            // Make the default value 1 for the Quantity property
            config.Property(o => o.Quantity).HasDefaultValue(1);

            // Make the Primary Key associated with the property UniqueKey
            config.HasKey(o => o.UniqueKey);

        });

        // Imagine a ton more customizations
    }
}