即如
EF 应用于 ASP.NET
微软推出EFCore必然是要服务于ASP.NET CORE 的项目
由于.NET6.0环境下 ASP.NET CORE项目的StartUp和program结合在了一起,所以使用的方法的也会有稍有不同,

1.创建一个空的ASP.NET CORE 项目（可以是WebApi）

添加安装EFCore的组件

2.创建类库，编写实体类和数据库上下文

namespace POCO.Entity
{
    //编写一个简单的一对多的实体关系
    public class Person
    {
        public int Id { get; set; } 
        public string Name { get; set; }
        public int Age { get; set; }
        public string address { get; set; }
    }
     public  class Pet
    {
        public int Id { get; set; }

        public string Name { get; set; }

        public Person Owener { get; set; }
    }
    public class PPDbContext :DbContext
    {
        public DbSet<Person> Persons { get; set; }

        public DbSet<Pet> Pets { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
        	//SqlServer的连接字符串
            var Connection = "server=.;database=EFCoreTest;uid=XXXX;pwd=XXXX";
            optionsBuilder.UseSqlServer(Connection);
        }
    }
}

类库项目也需要添加EFCore组件的依赖哦，csproj中添加或者直接右键项目在NulGet里安装即可

<PackageReference Include="Microsoft.EntityFrameworkCore" Version="6.0.1" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="6.0.1">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="6.0.1" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="6.0.1">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>

需要注意的一点是，你需要在ASP.NET CORE项目启动前，执行迁移完成建表，所以要先把
连接字符串写死，打开包管理操控台选择默认项目为类库执行建表，

当迁移建表完成后，要在ASP.NET CORE项目中使用时，我们再修改DbContext（数据库上下文）的连接方式并配置依赖注入。

3.创建测试项目，插入几条测试数据

这里用NUnit测试工具插入几条数据

namespace TheTestProject
{
    public class Tests
    {
        [SetUp]
        public void Setup()
        {
        }

        [Test]
        public void Test1()
        {
            PPDbContext context = new PPDbContext();

            Person zhangsan = new Person();
            zhangsan.Name = "法外狂徒";
            zhangsan.Age = 999;
            zhangsan.address = "上海";

            Person lisi = new Person();
            lisi.Name = "张三说刑法";
            lisi.Age = 998;
            lisi.address = "武汉";

            Pet pet = new Pet();
            pet.Name = "旺财";
            pet.Owener = zhangsan;

            Pet pet2 = new Pet();
            pet2.Name = "阿喵";
            pet2.Owener = zhangsan;

            Pet pet3 = new Pet();
            pet3.Name = "小黑";
            pet3.Owener = lisi;

            context.Persons.Add(zhangsan);
            context.Persons.Add(lisi);
            context.Pets.Add(pet);
            context.Pets.Add(pet2);
            context.Pets.Add(pet3);
            context.SaveChanges();

           
        }
    }
}

查看数据库

4.创建Controller把数据返回给前端

先把连接字符串写到配置文件里、

  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "ConnectionStrings" :
  {
      "LocalDb": "server=.;database=EFCoreTest;uid=XXXXXXXXXXX;pwd=XXXX"
  }
}

再改一下DbContext

public class PPDbContext :DbContext
    {
        public DbSet<Person> Persons { get; set; }

        public DbSet<Pet> Pets { get; set; }

        //编写数据库上下文的改造函数以方便ASP.NET CORE将属性和依赖注入
        public PPDbContext(DbContextOptions<PPDbContext> options):base(options)
        {
           
        }
    }

在Progrom中添加注入，并注入配置信息

builder.Services.AddDbContext<PPDbContext>(options => 
    options.UseSqlServer(Configuration.GetConnectionString("LocalDb")));

写一个Controller直接调用DbContext(这里为了方便就不使用持久层和业务层进行分层了)

[ApiController]
[Route("api/[Controller]/[action]")]
public EFCoreController:ControllerBase
{
	private PPDbContext _context;
	public EFCoreController(PPDbContext context)
	{
		_context = context;
	}
	public List<Pet> getPetsByPersonId(int id)
	{
		return _context.pets.Where(pet=>pet.Owner.Id == id).ToList();
	}
}

5.启动项目,到Swagger中进行测试