Net6 CodeFirst注入MySQL数据库上下文

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2022太难了，好多公司倒闭，互联网不景气，工作难找，苏州的C#/Net程序员的招聘更是少之又少，java，C，等其他语言也是供大于求，总之，难上加难！唯有珍惜现有工作方为上策，真心希望经济好转 

 1、先建DbContext层

使用VS2022新建一个webApi项目，然后添加一个类库，名称为：WebMysqlDbContext

对此类库添加Nuget引用，如下

Microsoft.EntityFrameworkCore.Design  6.0.8
Microsoft.EntityFrameworkCore.Relational  6.0.8
Microsoft.EntityFrameworkCore.Tools  6.0.8
Pomelo.EntityFrameworkCore.MySql  6.0.2

项目文件如下：

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="6.0.8">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
    <PackageReference Include="Microsoft.EntityFrameworkCore.Relational" Version="6.0.8" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="6.0.8">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
    <PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="6.0.2" />
  </ItemGroup>

</Project>

 

 

 DbDtos 用于存放数据库实体相关的类，内有一个学生类

namespace WebMysqlDbContext.DbDtos
{
    public class T_Student
    {
        public string? uid { get; set; }
        public string? studentName { get; set; }
        public string? studentNo { get; set; }
        public StudentSexEnum sex { get; set; } 
        public string? telephone { get; set; } 
        public bool isEnable { get; set; } = true;
        public DateTime createTime { get; set; }
    }

    public enum StudentSexEnum
    {
        男,
        女
    }
}

DbConfigs 用于存放数据库实体相关配置，用于设定字段长度，字段备注，表主键、外键等

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using WebMysqlDbContext.DbDtos;

namespace WebMysqlDbContext.DbConfigs
{ 
    internal class T_StudentConfig : IEntityTypeConfiguration<T_Student>
    {
        public void Configure(EntityTypeBuilder<T_Student> builder)
        {
            builder.ToTable("T_Students");
            builder.HasKey(A => A.uid);
            builder.Property(A => A.uid).HasColumnType("varchar(64)").HasComment("主键");
            builder.Property(A => A.studentName).HasColumnType("nvarchar(64)").HasComment("学生姓名");
            builder.Property(A => A.studentNo).HasColumnType("varchar(16)").HasComment("学号"); 
            builder.Property(A => A.telephone).HasColumnType("varchar(20)").HasComment("联系方式");  
            //全局过滤器
            builder.HasQueryFilter(A => A.isEnable == true);
        }
    }
}

MyDbContext.cs 为数据库上下文，用于数据库相关配置

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Design;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using WebMysqlDbContext.DbDtos;

namespace WebMysqlDbContext
{
    public class MyDbContext : DbContext
    {
        public DbSet<T_Student> Students { get; set; }
        public MyDbContext() : base()
        {
        }
        public MyDbContext(DbContextOptions<MyDbContext> options) : base(options)
        {
        } 

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            //关闭级联删除
            var foreignKeys = modelBuilder.Model.GetEntityTypes().SelectMany(e => e.GetForeignKeys()).Where(fk => fk.DeleteBehavior == DeleteBehavior.Cascade);
            foreach (var fk in foreignKeys)
            {
                fk.DeleteBehavior = DeleteBehavior.Restrict;
            }

            base.OnModelCreating(modelBuilder);
            //从当前程序集命名空间加载所有的IEntityTypeConfiguration
            modelBuilder.ApplyConfigurationsFromAssembly(this.GetType().Assembly);
        }
    }

    /// <summary>
    /// 开发环境专用  用于add-Migration 时使用
    /// </summary>
    public class MyDbContextFactory : IDesignTimeDbContextFactory<MyDbContext>
    {
        public MyDbContext CreateDbContext(string[] args)
        {
            var optionsBuilder = new DbContextOptionsBuilder<MyDbContext>();
            optionsBuilder.UseMySql<MyDbContext>("Server=localhost;Port=3306;Database=Student;Uid=root;Pwd=chen1234;", ServerVersion.AutoDetect("Server=localhost;Port=3306;Database=Student;Uid=root;Pwd=123456;"));

            return new MyDbContext(optionsBuilder.Options);
        }
    }
} 

2、webApi层相关操作

在webApi层引入如下Nuget包

Microsoft.EntityFrameworkCore.Design  6.0.8
Pomelo.EntityFrameworkCore.MySql  6.0.2

项目文件如下：

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <UserSecretsId>243f8ed9-608e-4fd3-95b5-6a55d59118f4</UserSecretsId>
    <DockerDefaultTargetOS>Linux</DockerDefaultTargetOS>
  </PropertyGroup>

  <ItemGroup>   
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="6.0.8">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>   
    <PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.15.1" />
    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.2.3" />
    <PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="6.0.2" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\WebMysqlDbContext\WebMysqlDbContext.csproj" />
  </ItemGroup>

</Project>

在Program.cs中注入数据库上下文

builder.Services.AddDbContext<MyDbContext>(options => options.UseMySql(builder.Configuration.GetConnectionString("studentDbContext"), ServerVersion.AutoDetect(builder.Configuration.GetConnectionString("studentDbContext"))));

配置文件如下：

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "studentDbContext": "Server=localhost;Port=3306;Database=Student;Uid=root;Pwd=123456;"
  }
}

在程序包管理控制台中初始化数据库

 

 输入

add-migration initdb 

update-database

3、去数据库中查看生成的数据库及数据表

 4、简单测试

using Microsoft.AspNetCore.Mvc;
using WebMysqlDbContext;
using WebMysqlDbContext.DbDtos;

namespace WebMySql.Controllers
{
    [ApiController]
    [Route("[controller]")]
    public class WeatherForecastController : ControllerBase
    { 

        private readonly ILogger<WeatherForecastController> _logger;
        private readonly MyDbContext context;
        public WeatherForecastController(ILogger<WeatherForecastController> logger, MyDbContext context)
        {
            _logger = logger;
            this.context = context;
        }

        [HttpGet(Name = "GetWeatherForecast")]
        public IActionResult Get()
        {
            T_Student student = new T_Student()
            {
                createTime = DateTime.Now,
                isEnable = true,
                sex = StudentSexEnum.女,
                studentName = "陈红",
                studentNo = "081309207",
                telephone = "18137070152",
                uid = Guid.NewGuid().ToString()
            };
            context.Students.Add(student);
            context.SaveChanges();
            var result = context.Students.ToList();
            return Ok(result);
        }
    }
}

swagger运行结果

数据库刷新后

 

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