完成第四章

第四章/一对一关系/Delivery.cs

@@ -0,0 +1,8 @@
+class Delivery
+{
+	public long Id { get; set; }
+	public string CompanyName { get; set; }//快递公司名
+	public String Number { get; set; }//快递单号
+	public Order Order { get; set; }//订单
+	public long OrderId { get; set; }//指向订单的外键
+}

第四章/一对一关系/DeliveryConfig.cs

@@ -0,0 +1,12 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+class DeliveryConfig : IEntityTypeConfiguration<Delivery>
+{
+	public void Configure(EntityTypeBuilder<Delivery> builder)
+	{
+		builder.ToTable("T_Deliveries");
+		builder.Property(d => d.CompanyName).IsUnicode().HasMaxLength(10);
+		builder.Property(d => d.Number).HasMaxLength(50);
+	}
+}

第四章/一对一关系/Migrations/20211110072933_init.cs

@@ -0,0 +1,62 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace 一对一关系.Migrations
+{
+    public partial class init : Migration
+    {
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "T_Orders",
+                columns: table => new
+                {
+                    Id = table.Column<long>(type: "bigint", nullable: false)
+                        .Annotation("SqlServer:Identity", "1, 1"),
+                    Name = table.Column<string>(type: "nvarchar(max)", nullable: false),
+                    Address = table.Column<string>(type: "nvarchar(max)", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_T_Orders", x => x.Id);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "T_Deliveries",
+                columns: table => new
+                {
+                    Id = table.Column<long>(type: "bigint", nullable: false)
+                        .Annotation("SqlServer:Identity", "1, 1"),
+                    CompanyName = table.Column<string>(type: "nvarchar(10)", maxLength: 10, nullable: false),
+                    Number = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: false),
+                    OrderId = table.Column<long>(type: "bigint", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_T_Deliveries", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_T_Deliveries_T_Orders_OrderId",
+                        column: x => x.OrderId,
+                        principalTable: "T_Orders",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_T_Deliveries_OrderId",
+                table: "T_Deliveries",
+                column: "OrderId",
+                unique: true);
+        }
+
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "T_Deliveries");
+
+            migrationBuilder.DropTable(
+                name: "T_Orders");
+        }
+    }
+}

第四章/一对一关系/Migrations/TestDbContextModelSnapshot.cs

@@ -0,0 +1,94 @@
+// <auto-generated />
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Metadata;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace 一对一关系.Migrations
+{
+    [DbContext(typeof(TestDbContext))]
+    partial class TestDbContextModelSnapshot : ModelSnapshot
+    {
+        protected override void BuildModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "6.0.0")
+                .HasAnnotation("Relational:MaxIdentifierLength", 128);
+
+            SqlServerModelBuilderExtensions.UseIdentityColumns(modelBuilder, 1L, 1);
+
+            modelBuilder.Entity("Delivery", b =>
+                {
+                    b.Property<long>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("bigint");
+
+                    SqlServerPropertyBuilderExtensions.UseIdentityColumn(b.Property<long>("Id"), 1L, 1);
+
+                    b.Property<string>("CompanyName")
+                        .IsRequired()
+                        .HasMaxLength(10)
+                        .IsUnicode(true)
+                        .HasColumnType("nvarchar(10)");
+
+                    b.Property<string>("Number")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("nvarchar(50)");
+
+                    b.Property<long>("OrderId")
+                        .HasColumnType("bigint");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("OrderId")
+                        .IsUnique();
+
+                    b.ToTable("T_Deliveries", (string)null);
+                });
+
+            modelBuilder.Entity("Order", b =>
+                {
+                    b.Property<long>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("bigint");
+
+                    SqlServerPropertyBuilderExtensions.UseIdentityColumn(b.Property<long>("Id"), 1L, 1);
+
+                    b.Property<string>("Address")
+                        .IsRequired()
+                        .IsUnicode(true)
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .IsUnicode(true)
+                        .HasColumnType("nvarchar(max)");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("T_Orders", (string)null);
+                });
+
+            modelBuilder.Entity("Delivery", b =>
+                {
+                    b.HasOne("Order", "Order")
+                        .WithOne("Delivery")
+                        .HasForeignKey("Delivery", "OrderId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Order");
+                });
+
+            modelBuilder.Entity("Order", b =>
+                {
+                    b.Navigation("Delivery");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

第四章/一对一关系/Order.cs

@@ -0,0 +1,7 @@
+class Order
+{
+	public long Id { get; set; }
+	public string Name { get; set; }//商品名
+	public string Address { get; set; }//收货地址
+	public Delivery? Delivery { get; set; }//快递信息
+}

第四章/一对一关系/OrderConfig.cs

@@ -0,0 +1,14 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+class OrderConfig : IEntityTypeConfiguration<Order>
+{
+	public void Configure(EntityTypeBuilder<Order> builder)
+	{
+		builder.ToTable("T_Orders");
+		builder.Property(o => o.Address).IsUnicode();
+		builder.Property(o => o.Name).IsUnicode();
+		builder.HasOne<Delivery>(o => o.Delivery).WithOne(d => d.Order)
+			.HasForeignKey<Delivery>(d => d.OrderId);
+	}
+}

第四章/一对一关系/Program.cs

@@ -0,0 +1,15 @@
+using Microsoft.EntityFrameworkCore;
+
+using TestDbContext ctx = new TestDbContext();
+Order order = new Order();
+order.Address = "北京市海淀区中关村南大街999号";
+order.Name = "USB充电器";
+Delivery delivery = new Delivery();
+delivery.CompanyName = "蜗牛快递";
+delivery.Number = "SN333322888";
+delivery.Order = order;
+ctx.Deliveries.Add(delivery);
+await ctx.SaveChangesAsync();
+Order order1 = await ctx.Orders.Include(o => o.Delivery)
+    .FirstAsync(o => o.Name.Contains("充电器"));
+Console.WriteLine($"名称：{order1.Name},单号：{order1.Delivery.Number}");

第四章/一对一关系/TestDbContext.cs

@@ -0,0 +1,19 @@
+using Microsoft.EntityFrameworkCore;
+
+class TestDbContext : DbContext
+{
+    public DbSet<Delivery> Deliveries { get; set; }
+    public DbSet<Order> Orders { get; set; }
+    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+    {
+        string connStr = "Server=.;Database=demo6;Trusted_Connection=True";
+        optionsBuilder.UseSqlServer(connStr);
+        optionsBuilder.LogTo(Console.WriteLine);
+    }
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        base.OnModelCreating(modelBuilder);
+        modelBuilder.ApplyConfigurationsFromAssembly(this.GetType().Assembly);
+    }
+}

第四章/一对一关系/一对一关系.csproj

@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+	<ItemGroup>
+		<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="6.0.0" />
+		<PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="6.0.0">
+			<PrivateAssets>all</PrivateAssets>
+			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+		</PackageReference>
+	</ItemGroup>
+</Project>

第四章/单向导航机制/Leave.cs

@@ -0,0 +1,10 @@
+class Leave
+{
+	public long Id { get; set; }
+	public User Requester { get; set; }//申请者
+	public User? Approver { get; set; } //审批者
+	public string Remarks { get; set; } //说明
+	public DateTime From { get; set; } //开始日期
+	public DateTime To { get; set; } //结束日期
+	public int Status { get; set; }//状态
+}

第四章/单向导航机制/LeaveConfig.cs

@@ -0,0 +1,13 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+class LeaveConfig : IEntityTypeConfiguration<Leave>
+{
+	public void Configure(EntityTypeBuilder<Leave> builder)
+	{
+		builder.ToTable("T_Leaves");
+		builder.HasOne<User>(l => l.Requester).WithMany();
+		builder.HasOne<User>(l => l.Approver).WithMany();
+		builder.Property(l => l.Remarks).HasMaxLength(1000).IsUnicode();
+	}
+}