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net core 使用ef core与数据库进行简单的交互

心存浪漫 2022-03-15 阅读 71
mysqlc#

1 安装程序包

  • Microsoft.EntityFrameworkCore                                            5.0.10
  • Pomelo.EntityFrameworkCore.MySql (5.0.0-alpha.2)           5.0.0
  • Microsoft.Bcl.AsyncInterfaces                                               5.0.10

2 创建一个实体Person.cs

namespace xxxxxxxxxx
{
    [Table("people")]
    public class Person
    {
        [Key]//设置主键
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public DateTime CreatedAt { get; set; }
    }
}

3 创建一个数据库上下文MyDbContext.cs,如下:

namespace xxxxxxxx
{
    public class MyDbContext : DbContext
    {
        public DbSet<Person> People { get; set; }

        public MyDbContext(DbContextOptions<MyDbContext> options) : base(options)
        {

        }
    }
}

4 配置appsettings.json

{
    "Logging": {
        "LogLevel": {
            "Default": "Information",
            "Microsoft": "Warning",
            "Microsoft.Hosting.Lifetime": "Information"
        }
    },
    "AllowedHosts": "*",
    "ConnectionStrings": {
        "MySQL": "server=192.168.1.22;userid=root;password=xxxxxx;database=test;"
    }
}

5 在Startup.cs注册MySQL数据库上下文服务

namespace MySQLSample
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext<MyDbContext>(options => options.UseMySql(Configuration.GetConnectionString("MySQL"), MySqlServerVersion.LatestSupportedServerVersion));//这里
            services.AddControllers();
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            //这里添加服务
            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}

6 创建一个名为PeopleController的控制器

namespace xxxxxxx.Controllers
{
    [ApiController]
    [Route("api/[controller]/[action]")]
    public class PeopleController : ControllerBase
    {
        private readonly MyDbContext _dbContext;
        public PeopleController(MyDbContext dbContext)
        {
            _dbContext = dbContext;
        }

        /// <summary>
        /// 创建
        /// </summary>
        /// <returns></returns>
        [HttpGet]
        public IActionResult Create()
        {
            var message = "";
            using (_dbContext)
            {
                var person = new Person
                {
                    FirstName = "Rector",
                    LastName = "Liu",
                    CreatedAt = DateTime.Now
                };
                _dbContext.People.Add(person);
                var i = _dbContext.SaveChanges();
                message = i > 0 ? "数据写入成功" : "数据写入失败";
            }
            return Ok(message);
        }

        /// <summary>
        /// 读取指定Id的数据
        /// </summary>
        /// <returns></returns>
        [HttpGet]
        public IActionResult GetById(int id)
        {
            using (_dbContext)
            {
                var list = _dbContext.People.Find(id);
                return Ok(list);
            }
        }
        /// <summary>
        /// 根据传入参数查询
        /// </summary>
        /// <returns></returns>
       
        [HttpGet]
        public List<Person> GetfirstName(string mess)
        {
            var k= _dbContext.Set<Person>().Where(b => b.FirstName == mess).ToList();
            return k;
        }
        /// <summary>
        /// 读取所有
        /// </summary>
        /// <returns></returns>
        [HttpGet]
        public IActionResult GetAll()
        {
            using (_dbContext)
            {
                var list = _dbContext.People.ToList();
                return Ok(list);
            }
        }
    }
}

数据库脚本

CREATE TABLE `people`  (
  `Id` int NOT NULL AUTO_INCREMENT,
  `FirstName` varchar(50) NULL,
  `LastName` varchar(50) NULL,
  `CreatedAt` datetime NULL,
  PRIMARY KEY (`Id`)
);

通过路径/api/控制器名/方法名,查看使用EF Core 5读取MySQL数据库操作是否成功,转自码友网的创建者-Rector

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