.NET之生成数据库全流程实现

开篇语

本文主要是回顾下从项目创建到生成数据到数据库(代码优先)的全部过程。采用EFCore作为ORM框架。

本次示例环境：vs2019、net5、mysql

创建项目

本次事例代码是用过vs2019创建的ASP.NET Core Web API项目

可以通过可视化界面创建或者通过命令行创建

dotnet new webapi -o Net5ByDocker

创建实体类

安装组件

    <PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="5.0.0" />
    <PackageReference Include="Pomelo.EntityFrameworkCore.MySql.Json.Newtonsoft" Version="5.0.0" />

增加实体类

    [Table("user")]
    public class User
    {
        public User()
        {
            Id = Guid.NewGuid().ToString();
        }

        public User(string account, string password, string creater) : this()
        {
            Account = account;
            Password = password;
            Deleted = false;
            SetCreater(creater);
        }

        [Key]
        [Comment("主键")]
        [StringLength(36)]
        [Required]
        public string Id { get; private set; }

        [Comment("帐号")]
        [StringLength(36)]
        [Required]
        public string Account { get; private set; }

        [Comment("密码")]
        [StringLength(36)]
        [Required]
        public string Password { get; private set; }

        [Comment("余额")]
        [Column(TypeName = "decimal(18, 2)")]
        [Required]
        public decimal Money { get; set; }

        [Comment("是否删除")]
        [Column(TypeName = "tinyint(1)")]
        [Required]
        public bool Deleted { get; private set; }

        [Comment("创建人")]
        [StringLength(20)]
        [Required]
        public string Creater { get; private set; }

        [Comment("创建时间")]
        [Required]
        public DateTime CreateTime { get; private set; }

        [Comment("修改人")]
        [StringLength(20)]
        [Required]
        public string Modifyer { get; private set; }

        [Comment("修改时间")]
        [Required]
        public DateTime ModifyTime { get; private set; }

        public void SetCreater(string name)
        {
            Creater = name;
            CreateTime = DateTime.Now;
            SetModifyer(name);
        }

        public void SetModifyer(string name)
        {
            Modifyer = name;
            ModifyTime = DateTime.Now;
        }
    }

这种只是增加实体类类型的一种方式，可能这种看着比较乱，还可以通过OnModelCreating实现，详情看参考文档

增加数据库上下文OpenDbContext

    public class OpenDbContext : DbContext
    {
        public OpenDbContext(DbContextOptions<OpenDbContext> options)
            : base(options)
        {
        }

        public DbSet<User> Users { get; set; }
    }

Startup注入连接数据库操作

            var connection = Configuration["DbConfig:Mysql:ConnectionString"];
            var migrationsAssembly = IntrospectionExtensions.GetTypeInfo(typeof(Startup)).Assembly.GetName().Name;
            services.AddDbContext<OpenDbContext>(option => option.UseMySql(connection, ServerVersion.AutoDetect(connection), x =>
            {
                x.UseNewtonsoftJson();
                x.MigrationsAssembly(migrationsAssembly);
            }));

生成迁移文件

引用组件

<PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="5.0.5">
<PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="5.0.5">

迁移命令

add-migration Init

结果

要看下生成的迁移文件是否是自己预期的那样子，也可以在这一步就生成数据库，命令：Update-Database

数据种子

增加OpenDbSend类，添加数据种子

    public class OpenDbSend
    {
        /// <summary>
        /// 生成数据库以及数据种子
        /// </summary>
        /// <param name="dbContext">数据库上下文</param>
        /// <param name="loggerFactory">日志</param>
        /// <param name="retry">重试次数</param>
        /// <returns></returns>
        public static async Task SeedAsync(OpenDbContext dbContext,
            ILoggerFactory loggerFactory,
            int? retry = 0)
        {
            int retryForAvailability = retry.Value;
            try
            {
                dbContext.Database.Migrate();//如果当前数据库不存在按照当前 model 创建，如果存在则将数据库调整到和当前 model 匹配
                await InitializeAsync(dbContext).ConfigureAwait(false);

                //if (dbContext.Database.EnsureCreated())//如果当前数据库不存在按照当前 model创建，如果存在则不管了。
                //  await InitializeAsync(dbContext).ConfigureAwait(false);
            }
            catch (Exception ex)
            {
                if (retryForAvailability < 3)
                {
                    retryForAvailability++;
                    var log = loggerFactory.CreateLogger<OpenDbSend>();
                    log.LogError(ex.Message);
                    await SeedAsync(dbContext, loggerFactory, retryForAvailability).ConfigureAwait(false);
                }
            }
        }

        /// <summary>
        /// 初始化数据
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public static async Task InitializeAsync(OpenDbContext context)
        {
            if (!context.Set<User>().Any())
            {
                await context.Set<User>().AddAsync(new User("azrng", "123456", "azrng")).ConfigureAwait(false);
                await context.Set<User>().AddAsync(new User("张三", "123456", "azrng")).ConfigureAwait(false);
            }
            await context.SaveChangesAsync().ConfigureAwait(false);
        }
    }

设置项目启动时候调用

        public static async Task Main(string[] args)
        {
            var host = CreateHostBuilder(args).Build();
            using (var scope = host.Services.CreateScope())
            {
                var services = scope.ServiceProvider;
                var loggerFactory = services.GetRequiredService<ILoggerFactory>();
                var _logger = loggerFactory.CreateLogger<Program>();
                try
                {
                    var openContext = services.GetRequiredService<OpenDbContext>();
                    await OpenDbSend.SeedAsync(openContext, loggerFactory).ConfigureAwait(false);
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, $"项目启动出错  {ex.Message}");
                }
            }

            await host.RunAsync().ConfigureAwait(false);
        }

生成数据库

启动项目，自动生成数据库

表结构如下

如果后期数据库字段或者结构有变动，可以再次生成迁移文件然后生成数据库

查询数据

    /// <summary>
    /// 用户接口
    /// </summary>
    public interface IUserService
    {
        string GetName();

        /// <summary>
        /// 查询用户信息
        /// </summary>
        /// <param name="account"></param>
        /// <returns></returns>
        Task<User> GetDetailsAsync(string account);
    }

    /// <summary>
    /// 用户实现
    /// </summary>
    public class UserService : IUserService
    {
        private readonly OpenDbContext _dbContext;

        public UserService(OpenDbContext dbContext)
        {
            _dbContext = dbContext;
        }

        public string GetName()
        {
            return "AZRNG";
        }

        ///<inheritdoc cref="IUserService.GetDetailsAsync(string)"/>
        public async Task<User> GetDetailsAsync(string account)
        {
            return await _dbContext.Set<User>().FirstOrDefaultAsync(t => t.Account == account).ConfigureAwait(false);
        }
    }

一般更推荐建立指定的返回Model类，然后只查询需要的内容，不直接返回实体类

控制器方法

        /// <summary>
        /// 查询用户详情
        /// </summary>
        /// <param name="account"></param>
        /// <returns></returns>
        [HttpGet]
        public async Task<ActionResult<User>> GetDetailsAsync(string account)
        {
            return await _userService.GetDetailsAsync(account).ConfigureAwait(false);
        }

查询结果

{
  "id": "e8976d0a-6ee9-4e2e-b8d8-1fe6e85b727b",
  "account": "azrng",
  "password": "123456",
  "money": 0,
  "deleted": false,
  "creater": "azrng",
  "createTime": "2021-05-09T15:48:45.730302",
  "modifyer": "azrng",
  "modifyTime": "2021-05-09T15:48:45.730425"
}

参考文档

实体类型：https://docs.microsoft.com/zh-cn/ef/core/modeling/entity-types?tabs=data-annotations

实体属性：https://docs.microsoft.com/zh-cn/ef/core/modeling/entity-properties?tabs=data-annotations%2Cwithout-nrt

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