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本文在项目中使用Migration工具创建数据库，主要包括三个方面的内容，一是在SignUp.Domain项目中创建数据库实体类，二是在SignUp.Infrastructure创建数据库实体配置，也就是实体属性与数据库字段的对应关系配置，三是创建DbContext类，数据库连接存放系统环境变量里面。

项目创建了WebApplicationBuilderExtensions类用于写相关配置代码，如数据库连接配置、Swagger、Cors、Redis等配置。以及实体类的一些基类。

 一、包引用

SignUp.Common 项目安装如下包：

Install-Package Swashbuckle.AspNetCore、

Install-Package System.Data.SqlClient

Install-Package AsmResolver.DotNet  -Version 5.0.1

Install-Package Microsoft.EntityFrameworkCore -Version 7.0.3

Install-Package Microsoft.EntityFrameworkCore.SqlServer -Version 7.0.3

Install-Package MediatR

SignUp.Infrastructure项目安装如下包：

Install-Package Microsoft.EntityFrameworkCore -Version 7.0.3

Install-Package Microsoft.EntityFrameworkCore.SqlServer -Version 7.0.3

Install-Package Microsoft.EntityFrameworkCore.Tools -Version 7.0.3

SignUp.WebApi项目安装如下包：

Install-Package Microsoft.EntityFrameworkCore.Design -Version 7.0.3

二、创建相关实体类

    public record SysUser : IAggregateRoot
    {
        public Guid Id { get; set; }
        /// <summary>
        /// 用户名
        /// </summary>
        public string UserName { get; set; }
        /// <summary>
        /// 用户密码
        /// </summary>
        private string Password;
        /// <summary>
        /// 真实姓名
        /// </summary>
        public string? RealName { get; set; }
        /// <summary>
        /// 用户类型
        /// </summary>
        public string? UserType { get; set; }
        /// <summary>
        /// 角色Id
        /// </summary>
        public Guid? RoleId { get; set; }
        /// <summary>
        /// 角色
        /// </summary>
        public string? RoleName { get; set; }
        /// <summary>
        /// 是否禁用
        /// </summary>
        public bool IsDisable { get; set; }
    }
    public record SysRole : IAggregateRoot
    {
        public Guid Id { get; set; }
        /// <summary>
        /// 角色名称
        /// </summary>
        public string Name { get; set; }
        /// <summary>
        /// 备注
        /// </summary>
        public string? Remark { get; set; }
    }
    public record SysRoleDetails
    {
        public Guid Id { get; set; }
        /// <summary>
        /// 角色Id
        /// </summary>
        public Guid RoleId { get; set; }
        /// <summary>
        /// 菜单Id
        /// </summary>
        public Guid MenuId { get; set; }
    }
    public record SysMenu :BaseEntity, IAggregateRoot
    {
        /// <summary>
        /// 菜单名称
        /// </summary>
        public string Name { get; set; }

        /// <summary>
        /// 菜单分类
        /// </summary>
        public string? Sort { get; set; }

        /// <summary>
        /// 父层Id
        /// </summary>
        public Guid? ParentId { get; set; }

        /// <summary>
        /// 路由权限值
        /// </summary>
        public string? RouterName { get; set; }

        /// <summary>
        /// 菜单级别
        /// </summary>
        public int Level { get; set; }

        /// <summary>
        /// 备注
        /// </summary>
        public string? Remark { get; set; }

        public SysMenu[] Children { get; set; }
    }
    public record SysConfig : IAggregateRoot
    {
        public float Id { get; set; }
        /// <summary>
        /// 名称
        /// </summary>
        public string Name { get; set; }
        /// <summary>
        /// 值
        /// </summary>
        public string Value { get; set; }
    }

三、创建实体配置类

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
using SignUp.Domain.Entities;

namespace SignUp.Infrastructure.Configs
{
    public class SysMenuConfig : IEntityTypeConfiguration<SysMenu>
    {
        public void Configure(EntityTypeBuilder<SysMenu> builder)
        {
            builder.ToTable("SysMenu");
            builder.HasKey(f => f.Id);
            builder.Property(f => f.Name).HasMaxLength(200).IsUnicode(true);
            builder.Property(f => f.Sort).HasMaxLength(20).IsUnicode(true);
            builder.Property(f => f.Remark).HasMaxLength(400).IsUnicode(true);
            builder.Ignore(f => f.Children);
        }
    }
    public class SysRoleConfig : IEntityTypeConfiguration<SysRole>
    {
        public void Configure(EntityTypeBuilder<SysRole> builder)
        {
            builder.ToTable("SysRole");
            builder.HasKey(f => f.Id);
            builder.Property(f => f.Name).HasMaxLength(200).IsUnicode(true);
            builder.Property(f => f.Remark).HasMaxLength(400).IsUnicode(true);
        }
    }
    public class SysRoleDetailsConfig : IEntityTypeConfiguration<SysRoleDetails>
    {
        public void Configure(EntityTypeBuilder<SysRoleDetails> builder)
        {
            builder.ToTable("SysRoleDetails");
            builder.HasKey(f => f.Id);
        }
    }
    public class SysMenuConfig : IEntityTypeConfiguration<SysMenu>
    {
        public void Configure(EntityTypeBuilder<SysMenu> builder)
        {
            builder.ToTable("SysMenu");
            builder.HasKey(f => f.Id);
            builder.Property(f => f.Name).HasMaxLength(200).IsUnicode(true);
            builder.Property(f => f.Sort).HasMaxLength(20).IsUnicode(true);
            builder.Property(f => f.Remark).HasMaxLength(400).IsUnicode(true);
            builder.Ignore(f => f.Children);
        }
    }
}

四、创建DbContext

using Microsoft.EntityFrameworkCore;
using SignUp.Domain.Entities;
using System.Reflection;

namespace SignUp.Infrastructure
{
    public class SignUpDbContext : DbContext
    {
        public DbSet<RecruitBase> RecruitBase { get; set; }
        public DbSet<RecruitPosition> RecruitPosition { get; set; }
        public DbSet<RecruitUser> RecruitUser { get; set; }
        public DbSet<TalentBase> TalentBase { get; set; }
        public DbSet<TalentBaseCheck> TalentBaseCheck { get; set; }
        public DbSet<TalentEnterviewTicket> TalentEnterviewTicket { get; set; }
        public DbSet<TalentWrittenTicket> TalentWrittenTicket { get; set; }
        public DbSet<SysLog> SysLog { get; set; }
        public DbSet<SysMenu> SysMenu { get; set; }
        public DbSet<SysUser> SysUser { get; set; }
        public DbSet<SysRole> SysRole { get; set; }
        public DbSet<SysRoleDetails> SysRoleDetails { get; set; }
        public DbSet<TalentFile> TalentFile { get; set; }
        public SignUpDbContext(DbContextOptions<SignUpDbContext> opt) : base(opt)
        {
        }
        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
            modelBuilder.ApplyConfigurationsFromAssembly(Assembly.GetExecutingAssembly());
        }
    }
}

五、创建DbContextFactory类供Migration工具操作数据库使用

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Design;
using Microsoft.Extensions.Configuration;

namespace SignUp.Infrastructure
{
    //migration操作数据库使用
    public class DbContextFactory : IDesignTimeDbContextFactory<SignUpDbContext>
    {
        public SignUpDbContext CreateDbContext(string[] args)
        {
            var builder = new DbContextOptionsBuilder<SignUpDbContext>();
            //从appsettings.json获取数据库连接
            //IConfigurationRoot configuration = new ConfigurationBuilder()
            //    .SetBasePath(Directory.GetCurrentDirectory())
            //    .AddJsonFile("appsettings.json")
            //    .Build();
            //string connStr = configuration.GetValue<string>("DefaultDB:ConnStr");
            //从环境变量里面获取数据库连接
            IConfigurationRoot configuration = new ConfigurationBuilder().AddEnvironmentVariables().Build();
            string connStr = configuration.GetValue<string>("DefaultDB:ConnStr");
            builder.UseSqlServer(connStr);
            return new SignUpDbContext(builder.Options);
        }
    }
}

六、执行Migration命令创建数据库

Add-Migration init

Update-database

附：WebApplicationBuilderExtensions源码

using Microsoft.AspNetCore.Builder;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using SignUp.Common.Commons;
using SignUp.Common.EFCore;
using SignUp.Common.EFCore.DBConfiguration;
using System.Data.SqlClient;

namespace SignUp.Common.Initializer
{
    public static class WebApplicationBuilderExtensions
    {
        public static void ConfigureDbConfiguration(this WebApplicationBuilder builder)
        {
            //从数据库中读取相关配置信息，如Redis链接
            builder.Host.ConfigureAppConfiguration((hostCtx, configBuilder) =>
            {
                //不能使用ConfigureAppConfiguration中的configBuilder去读取配置，否则就循环调用了，因此这里直接自己去读取配置文件
                //读取appsettings.json文件配置
                //var configRoot = new ConfigurationBuilder().AddJsonFile("appsettings.json").Build();
                //string connStr = configRoot.GetValue<string>("DefaultDB:ConnStr");
                //读取环境变量配置
                //string connStr = builder.Configuration.GetValue<string>("DefaultDB:ConnStr");
                //configBuilder.AddDbConfiguration(() => new SqlConnection(connStr), reloadOnChange: true, reloadInterval: TimeSpan.FromSeconds(5));
            });
        }
        public static void ConfigureExtraServices(this WebApplicationBuilder builder, InitializerOptions initOptions)
        {
            IServiceCollection services = builder.Services;
            IConfiguration configuration = builder.Configuration;
            var assemblies = ReflectionHelper.GetAllReferencedAssemblies();
            //配置数据库链接
            services.AddAllDbContexts(ctx =>
            {
                //连接字符串如果放到appsettings.json中，会有泄密的风险
                //如果放到UserSecrets中，每个项目都要配置，很麻烦
                //因此这里推荐放到环境变量中。
                string connStr = configuration.GetValue<string>("DefaultDB:ConnStr");
                ctx.UseSqlServer(connStr);
            }, assemblies);
        }
    }
}

项目解决方案截图如下：

附：asp.net core webapi项目实例源代码锦集下载（72个）