NetCore下使用EFCore CodeFirst 方式创建更新数据库
项目结构图如下：
IService 主要是接口 ，Service 是服务处理，Models 各种数据实体，Repository 数据访问处理
1、首先在Models 项目下创建类
1 namespace Models
2 {
3 [Table("User")]
4 public class BaseUser
5 {
6 [Key]
7 [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
8 public int Id { get; set; }
9 [MaxLength(20)]
10 public string UserName { get; set; }
11 }
12 }
1 namespace Models
2 {
3 [Table("Role")]
4 public class Role
5 {
6 [Key]
7 [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
8 public int Id { get; set; }
9 [MaxLength(20)]
10 [Required]
11 public string RoleName { get; set; }
12
13 }
14 }
1 namespace Models
2 {
3 [Table("UserRole")]
4 public class UserRole
5 {
6 [Key]
7 [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
8 public int Id { get; set; }
9 [ForeignKey("UserID")]
10 public virtual BaseUser User { get; set; }
11 [ForeignKey("RoleID")]
12 public virtual Role Role { get; set; }
13
14 }
15 }
2、在 Repository 项目下创建DbContext类
1 namespace Repository
2 {
3 public partial class MiveDb:DbContext
4 {
5 public MiveDb()
6 {
7
8 }
9
10 public MiveDb(DbContextOptions<MiveDb> options)
11 :base(options)
12 {
13
14 }
15
16 protected override void OnModelCreating(ModelBuilder modelBuilder)
17 {
18 base.OnModelCreating(modelBuilder);
19 }
20
21 public virtual DbSet<Movie> Movie { get; set; }
22 public virtual DbSet<BaseUser> User { get; set; }
23 public virtual DbSet<Role> Role { get; set; }
24 public virtual DbSet<UserRole> UserRole { get; set; }
25 }
26 }
3、在Web项目下的appsettings.json文件中添加数据库连接字符串，添加后如下：
1 {
2 "Logging": {
3 "LogLevel": {
4 "Default": "Warning"
5 }
6 },
7 "AllowedHosts": "*",
8 "ConnectionStrings": {
9 "DefaultConnection": "Data Source=127.0.0.1;Initial Catalog=MovieDb;user id=sa;password=sa@123;Max Pool Size=512;Min Pool Size=5"
10 }
11 }
4、在webapp 配置 Startup.cs 下进行配置
4.1 创建一个方法用于程序集注入
1 /// <summary>
2 /// 自动注册服务——获取程序集中的实现类对应的多个接口
3 /// </summary>
4 /// <param name="services">服务集合</param>
5 /// <param name="assemblyName">程序集名称</param>
6 public void AddAssembly(IServiceCollection services, string assemblyName)
7 {
8 if (!String.IsNullOrEmpty(assemblyName))
9 {
10 Assembly assembly = Assembly.Load(assemblyName);
11 List<Type> ts = assembly.GetTypes().Where(u => u.IsClass && !u.IsAbstract && !u.IsGenericType).ToList();
12 foreach (var item in ts.Where(s => !s.IsInterface))
13 {
14 var interfaceType = item.GetInterfaces();
15 if (interfaceType.Length == 1)
16 {
17 services.AddTransient(interfaceType[0], item);
18 }
19 if (interfaceType.Length > 1)
20 {
21 services.AddTransient(interfaceType[1], item);
22 }
23 }
24 }
25 }
26
4.2 在 Startup.cs 中 ConfigureServices 方法中添加注入
1 AddAssembly(services, "IService");
2 AddAssembly(services, "Service");
3 services.AddDbContext<MiveDb>(options =>
4 {
5 var connection = Configuration.GetConnectionString("DefaultConnection");
6 options.UseSqlServer(
7 connection
8 );
9 });
4.3 按照项目需要，引用个项目
5、打开命令行控制台，切换到 Repository 项目
PM> Add-Migration FirstMigration
执行以上命令，备注：
FirstMigration 名字任意取
中间可能会遇见各种问题，主要是各个项目之间的引用就可以解决
执行成功后，Repository 中会出现 如图
但是发现在TestMovieDB.cs这个文件中有一个错误
SqlServerValueGenerationStrategy 缺少引用
1 namespace Repository.Migrations
2 {
3 public partial class TestMovieDB : Migration
4 {
5 protected override void Up(MigrationBuilder migrationBuilder)
6 {
7 migrationBuilder.CreateTable(
8 name: "Movie",
9 columns: table => new
10 {
11 Id = table.Column<int>(nullable: false)
12 .Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),
13 Title = table.Column<string>(maxLength: 50, nullable: true),
14 Info = table.Column<string>(maxLength: 500, nullable: true),
15 CreateTime = table.Column<DateTime>(nullable: false)
16 },
17 constraints: table =>
18 {
19 table.PrimaryKey("PK_Movie", x => x.Id);
20 });
21
22 migrationBuilder.CreateTable(
23 name: "Role",
24 columns: table => new
25 {
26 Id = table.Column<int>(nullable: false)
27 .Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),
28 RoleName = table.Column<string>(maxLength: 20, nullable: false)
29 },
30 constraints: table =>
31 {
32 table.PrimaryKey("PK_Role", x => x.Id);
33 });
34
35 migrationBuilder.CreateTable(
36 name: "User",
37 columns: table => new
38 {
39 Id = table.Column<int>(nullable: false)
40 .Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),
41 UserName = table.Column<string>(maxLength: 20, nullable: true)
42 },
43 constraints: table =>
44 {
45 table.PrimaryKey("PK_User", x => x.Id);
46 });
47
48 migrationBuilder.CreateTable(
49 name: "UserRole",
50 columns: table => new
51 {
52 Id = table.Column<int>(nullable: false)
53 .Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),
54 UserID = table.Column<int>(nullable: true),
55 RoleID = table.Column<int>(nullable: true)
56 },
57 constraints: table =>
58 {
59 table.PrimaryKey("PK_UserRole", x => x.Id);
60 table.ForeignKey(
61 name: "FK_UserRole_Role_RoleID",
62 column: x => x.RoleID,
63 principalTable: "Role",
64 principalColumn: "Id",
65 onDelete: ReferentialAction.Restrict);
66 table.ForeignKey(
67 name: "FK_UserRole_User_UserID",
68 column: x => x.UserID,
69 principalTable: "User",
70 principalColumn: "Id",
71 onDelete: ReferentialAction.Restrict);
72 });
73
74 migrationBuilder.CreateIndex(
75 name: "IX_UserRole_RoleID",
76 table: "UserRole",
77 column: "RoleID");
78
79 migrationBuilder.CreateIndex(
80 name: "IX_UserRole_UserID",
81 table: "UserRole",
82 column: "UserID");
83 }
84
85 protected override void Down(MigrationBuilder migrationBuilder)
86 {
87 migrationBuilder.DropTable(
88 name: "Movie");
89
90 migrationBuilder.DropTable(
91 name: "UserRole");
92
93 migrationBuilder.DropTable(
94 name: "Role");
95
96 migrationBuilder.DropTable(
97 name: "User");
98 }
99 }
100 }
没关系，这个问题明显是缺少 对dll 的引用，我们引用即可
接着引用 Microsoft.EntityFrameworkCore.SqlServer dll，版本根据实际需求引用
这个时候虽然成功了，但是数据库中的数据还未被创建
6、执行数据库更新操作
1 PM> Update-Database -Verbose
出现这些就表示成功了，接着我们看数据库
此时数据库已经创建好了！
7、有没有发现数据库的名称和我们DbContext 名字一样
具体啥原因没仔细研究
