使用 ASP.NET Core 和 Entity Framework Core 入门

先决条件

安装以下组件：

• .NET Core 2.0.0 SDK 或更高版本。
• 已安装 ASP.NET 和 Web 开发工作负载的 Visual Studio 2017 15.3 版或更高版本

使用EF code First 创建学生信息

1.添加student类

public class Student
    {
        public int ID { get; set; }
        [StringLength(50)]
        public string LastName { get; set; }
        [StringLength(60, ErrorMessage = "First name cannot be longer than 50 characters.")]
        public string FirstMidName { get; set; }
        [DataType(DataType.Date)]
        [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
        public DateTime EnrollmentDate { get; set; }

        public ICollection<Enrollment> Enrollments { get; set; }
    }

2.创建的数据库上下文（添加DataContext类继承Microsoft.EntityFrameworkCore.DbContext）

namespace EFCoreSample.Models
{
    public class DataContext: DbContext
    {
        public DataContext(DbContextOptions<DataContext> options)
            : base(options)
        {


        }
        public DbSet<Student> Students { get; set; }
        //public DbSet<Course> Courses { get; set; }
        //public DbSet<Enrollment> Enrollments { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {

            //modelBuilder.Entity<Course>().ToTable("Course");
            //modelBuilder.Entity<Enrollment>().ToTable("Enrollment");
            modelBuilder.Entity<Student>().ToTable("Student");
        }
    }

}

3.上下文注册依赖关系注入  

   1.appsettings.json配置数据库连接字符串

{
  "ConnectionStrings": {
    "SqlServer": "Data Source=.;Initial Catalog=SchoolDb;Integrated Security=True"
  },
  "Logging": {
    "IncludeScopes": false,
    "LogLevel": {
      "Default": "Warning"
    }
  }
}

 2.打开Startup.cs  ConfigureServices方法添加代码

public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext<DataContext>(options =>
            options.UseSqlServer(Configuration.GetConnectionString("SqlServer")));
            services.AddMvc();
        }

3.创建数据库已经初始化数据

添加DbInitializer.cs

 public static class DbInitializer
    {
        public static void Initialize(DataContext context)
        {
            //当数据库数据为空时,默认填充数据
            context.Database.EnsureCreated();
            if (context.Students.Any()) 
            {
                return;
            }
            var students = new Student[]
             {
            new Student{FirstMidName="Carson",LastName="Alexander",EnrollmentDate=DateTime.Parse("2005-09-01")},
            new Student{FirstMidName="Meredith",LastName="Alonso",EnrollmentDate=DateTime.Parse("2002-09-01")},
            new Student{FirstMidName="Arturo",LastName="Anand",EnrollmentDate=DateTime.Parse("2003-09-01")},
            new Student{FirstMidName="Gytis",LastName="Barzdukas",EnrollmentDate=DateTime.Parse("2002-09-01")},
            new Student{FirstMidName="Yan",LastName="Li",EnrollmentDate=DateTime.Parse("2002-09-01")},
            new Student{FirstMidName="Peggy",LastName="Justice",EnrollmentDate=DateTime.Parse("2001-09-01")},
            new Student{FirstMidName="Laura",LastName="Norman",EnrollmentDate=DateTime.Parse("2003-09-01")},
            new Student{FirstMidName="Nino",LastName="Olivetto",EnrollmentDate=DateTime.Parse("2005-09-01")}
             };
            foreach (Student s in students)
            {
                context.Students.Add(s);
            }
            context.SaveChanges();
          
        }
    }

找到Program.cs Main方法添加代码

 public static void Main(string[] args)
        {
            var host = BuildWebHost(args);

            using (var scope = host.Services.CreateScope())
            {
                var services = scope.ServiceProvider;
                try
                {
                    var context = services.GetRequiredService<DataContext>();
                    DbInitializer.Initialize(context);
                   
                }
                catch (Exception ex)
                {
                    var logger = services.GetRequiredService<ILogger<Program>>();
                    logger.LogError(ex, "An error occurred while seeding the database.");
                }
            }

            host.Run();
        }

ps:可以添加相应的Controller和view运行项目操作数据

更多例子请参考 https://docs.microsoft.com/zh-cn/aspnet/core/data/ef-mvc/intro