EF Core Owned Entity Types

前言

像地址的物件，在 EF Core 中有那些的設定方式呢?
預設會是在原有的 Table 中增加欄位。
也可以指定欄位名稱，
或是讓它存到別的資料表。

實作

新增 Address 物件(它沒有 Id 哦~)

public class Address
{
    public string Street { get; set; }
    public string City { get; set; }
    public string Country { get; set; }
}

設定 Customer 有 2 個 Address 的屬性(ShipToAddress, BillToAddress)

public class Customer
{
    private string _validUsername;
    public Customer()
    {
        Orders = new HashSet<Order>();
    }
    public int Id { get; set; }

    [Required, MaxLength(50)]
    public string FirstName { get;set; }

    [Required, MaxLength(50)]
    public string LastName { get; set; }


    //public string Username { get; set; }
    [Required, MaxLength(50)]
    public string Username
    {
        get
        {
            return _validUsername;
        }
    }

    public string FullName => FirstName+ " " + LastName;

    //[NotMapped]
    //public byte[] Checksum { get; set; }
    public ICollection<Order> Orders { get; set; }

    public void SetUsername(string username)
    {
        string specialCharacters = ".*(?=.*[@#$%^&+=(){}<>!~_*?]).*$";
        bool usernameConatinsSpecialCharacters
            = username.Any(x => specialCharacters.Contains(x));
        if(usernameConatinsSpecialCharacters)
        {
            throw new ArgumentException("Special characters are not allowed in username", username);
        }
        _validUsername = username;
    }

    private readonly Dictionary<string, object> _data = new Dictionary<string, object>();
    public object this[string key]
    {
        get => _data[key];
        set => _data[key]= value;
    }

    public Address ShipToAddress { get; set; }
    public Address BillToAddress { get; set; }
}

在 DbContext 類別中 OnModelCreating Method 設定 OwnsOne，

public partial class 你的Context: DbContext
{
    // ... other codes ...
    public virtual DbSet<Customer> Customers { get; set; } = null!;

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Customer>(entity =>
        {
            entity.HasKey(e=>e.Id);
            //entity.Property<DateTime>("LastUpdated").HasDefaultValue(new DateTime(2020, 4, 9));
            // codes ...
            entity.OwnsOne(e => e.ShipToAddress)
                .Property(e => e.Street)
                .IsRequired();

            entity.OwnsOne(e => e.BillToAddress)
                .Property(e => e.Street)
                .IsRequired();
        });
    }

}

更新到 DB 後，就會新增 6 個欄位，如下，

接再來，將 ShipToAddress 中 Street 的欄位名稱改成 ShiptoStreet，
將 BillToAddress 屬性資料改存到 BillToAddresses 資料表。
在 DbContext 類別中 OnModelCreating Method 調整，

public partial class 你的Context: DbContext
{
    // ... other codes ...
    public virtual DbSet<Customer> Customers { get; set; } = null!;

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Customer>(entity =>
        {
            entity.HasKey(e=>e.Id);
            //entity.Property<DateTime>("LastUpdated").HasDefaultValue(new DateTime(2020, 4, 9));
            // codes ...
            entity.OwnsOne(e => e.ShipToAddress)
                .Property(e => e.Street)
                .IsRequired()
                .HasColumnName("ShipToAddress");

            entity.OwnsOne(e => e.BillToAddress)
                .ToTable("BillToAddresses")
                .Property(e => e.Street)
                .IsRequired();
        });
    }

}

透過 update-database 後，
DB 中 Customers資料表中欄位名稱從 ShipToAddress_Street 已經改成 ShiptoStreet，
也新增了 BillToAddress 。

參考資訊

擁有的實體類型