EF核心3 1对0关系问题

Question

我试图定义一个关系，在这个关系中，一个客户可以有0或1个地址。对于这种关系，我希望在Addresses表中有customerId，但我不希望在Customer表中有addressId。听起来很简单？我看了一些样本，但是在OnModelCreating中缺少一些属性，比如hasForeignKey或者hasOptional，所以我看的其他样本都不能用。我使用的是EF Core 3.15版本。无论我怎么尝试，迁移都是在Customer表中添加一个addressId列。我希望能够用sql语句 "delete from addresses "删除所有地址。

以下是我的2个实体

public class AddressEntity
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public Guid AddressId { get; set; }
    public string Line1 { get; set; }
    public string City { get; set; }
    public string State { get; set; }
    public string PostalCode { get; set; }
    public string Country { get; set; }
    public virtual Guid Customer { get; set; }
}

    public class CustomerEntity
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public Guid CustomerId { get; set; }
    public string CustomerName { get; set; }
    public string CustomerEmail { get; set; }
    public virtual AddressEntity Address { get; set; }
}

以下是我的迁移代码

  protected override void Up(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.CreateTable(
            name: "Addresses",
            columns: table => new
            {
                AddressId = table.Column<Guid>(nullable: false),
                Line1 = table.Column<string>(nullable: true),
                City = table.Column<string>(nullable: true),
                State = table.Column<string>(nullable: true),
                PostalCode = table.Column<string>(nullable: true),
                Country = table.Column<string>(nullable: true),
                Customer = table.Column<Guid>(nullable: false)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_Addresses", x => x.AddressId);
            });

        migrationBuilder.CreateTable(
            name: "Customers",
            columns: table => new
            {
                CustomerId = table.Column<Guid>(nullable: false),
                CustomerName = table.Column<string>(nullable: true),
                CustomerEmail = table.Column<string>(nullable: true),
                AddressId = table.Column<Guid>(nullable: true)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_Customers", x => x.CustomerId);
                table.ForeignKey(
                    name: "FK_Customers_Addresses_AddressId",
                    column: x => x.AddressId,
                    principalTable: "Addresses",
                    principalColumn: "AddressId",
                    onDelete: ReferentialAction.Restrict);
            });

        migrationBuilder.CreateIndex(
            name: "IX_Customers_AddressId",
            table: "Customers",
            column: "AddressId");
    }

Answer 1

我想，这个例子可以解决你的问题。

https:/anthonygiretti.com20180111entity-framework-core-2-table-splitting

Answer 2

首先，写下你的 AddressEntity 和 CustomerEntity 如下所示。

public class AddressEntity
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public Guid CustomerId { get; set; }
    public string Line1 { get; set; }
    public string City { get; set; }
    public string State { get; set; }
    public string PostalCode { get; set; }
    public string Country { get; set; }

    public CustomerEntity Customer { get; set; }
}

public class CustomerEntity
{
   [Key]
   [DatabaseGenerated(DatabaseGeneratedOption.None)]
   public Guid CustomerId { get; set; }
   public string CustomerName { get; set; }
   public string CustomerEmail { get; set; }

   public AddressEntity Address { get; set; }
}

现在，在 OnModelCreating 如下图所示。

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<CustomerEntity>()
        .HasOne(c => c.Address)
        .WithOne(a => a.Customer)
        .HasForeignKey<AddressEntity>(a => a.CustomerId);
}

现在产生一个全新的迁移，希望一切都能如期产生。