.NET6 + EF Core + MySQL 创建实体和数据库、EFCore 数据迁移、属性导航

一、创建 asp.net core web(MVC)项目

二、导包

1. Microsoft.EntityFrameworkCore.Design
2. Microsoft.EntifyFrameworkCore.Tools
3. Pomelo.EntityFrameworkCore.MySql

三、创建实例

这里创建了两个实例

namespace demo.Models
{
    public class Supplier
    {
        [DatabaseGenerated(DatabaseGeneratedOption.None)]//自增
        public long SupplierId { get; set; }
        public string SupplierName { get; set; }
        public string Abbreviation { get; set; }
        public List<SupplierType> SupplierTypes { get; set; } = new List<SupplierType>();
        public string province { get; set; }
        public string City { get; set; }
        public string Address { get; set; }
        public string Note { get; set; }
        public bool IsActive { get; set; }
    }
}

namespace demo.Models
{
    public class SupplierType
    {
        [Key]
        public int TypeCode { get; set; }
        public string TypeName { get; set; }
        public Supplier Supplier { get; set; }
    }
}

四、为实体类创建配置

namespace demo.Data
{
    public class SupplierConfig : IEntityTypeConfiguration<Supplier>
    {

        public void Configure(EntityTypeBuilder<Supplier> builder)
        {
            builder.ToTable("T_Supplier");
            builder.Property(a => a.SupplierId).IsRequired();//不能为空
            builder.Property(a => a.SupplierName).IsRequired();
            builder.Property(a => a.SupplierTypes).IsRequired();
        }
    }

namespace demo.Data
{
    public class SupplierTypeConfig : IEntityTypeConfiguration<SupplierType>
    {
        public void Configure(EntityTypeBuilder<SupplierType> builder)
        {
            builder.ToTable("SupplierType");
            builder.HasOne<Supplier>(c => c.Supplier).WithMany(a => a.SupplierTypes);//属性导航
        }
    }
}

五、创建数据上下文类

创建MyDbContext.cs 继承DbContext

 namespace demo.Data
{
    public class MyDbContext:DbContext
    {
        //添加实体类
        public DbSet<Supplier> suppliers{ get; set; }
        public DbSet<SupplierType> supplierTypes { get; set; }
        //构造函数
        public MyDbContext(DbContextOptions<MyDbContext> option) : base(option) { }
    }
}

六、连接MySql配置

1. 查询mysql版本
2. 配置appsettings.json

   {
     "Logging": {
       "LogLevel": {
         "Default": "Information",
         "Microsoft.AspNetCore": "Warning"
       }
     },
     "AllowedHosts": "*",
      
     "ConnectionStrings": {
       "DefaultConnection": "server=localhost;port=3306;uid=root;pwd=123456;database=demo1"// demo1创建的数据库名
     }
   }

3.  配置Program.cs

   public class Program
   {
       public static void Main(string[] args)
       {
           var builder = WebApplication.CreateBuilder(args);
   
           // Add services to the container.
           builder.Services.AddControllersWithViews();
           //配置这段代码
           builder.Services.AddDbContext<MyDbContext>(options =>
          {
               options.UseMySql(builder.Configuration.GetConnectionString("DefaultConnection"), 
               new MySqlServerVersion(new Version(5, 7, 26)));
   
          });//5 7 26为数据库版本,DefaultConnection 对应json配置的名
   
           var app = builder.Build();//一定要在 var app = builder.Build();上面配置，否则不会构建
   
           // Configure the HTTP request pipeline.
           if (!app.Environment.IsDevelopment())
           {
               app.UseExceptionHandler("/Home/Error");
               // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
               app.UseHsts();
           }
           app.UseHttpsRedirection();
           app.UseStaticFiles();
           app.UseRouting();
           app.UseAuthorization();
           app.MapControllerRoute(
               name: "default",
               pattern: "{controller=Home}/{action=Index}/{id?}");
           app.Run();      
       }
   }

迁移

Add-Migration init

Update-Database