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
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 options) : base(options) { } public DbSet 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 (option => option.UseMySql(connection, ServerVersion.AutoDetect(connection), x => { x.UseNewtonsoftJson(); x.MigrationsAssembly(migrationsAssembly); }));
生成迁移文件
引用组件
迁移命令
add-migration Init
结果
image.png 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 { /// /// 生成数据库以及数据种子 /// /// 数据库上下文 /// 日志 /// 重试次数 /// 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 (); log.LogError(ex.Message); await SeedAsync(dbContext, loggerFactory, retryForAvailability).ConfigureAwait(false); } } } /// /// 初始化数据 /// /// /// public static async Task InitializeAsync(OpenDbContext context) { if (!context.Set ().Any()) { await context.Set ().AddAsync(new User("azrng", "123456", "azrng")).ConfigureAwait(false); await context.Set ().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 (); var _logger = loggerFactory.CreateLogger (); try { var openContext = services.GetRequiredService (); 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
image.png 表结构如下
image.png 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
/// /// 用户接口 /// public interface IUserService { string GetName(); /// /// 查询用户信息 /// /// /// Task GetDetailsAsync(string account); } /// /// 用户实现 /// public class UserService : IUserService { private readonly OpenDbContext _dbContext; public UserService(OpenDbContext dbContext) { _dbContext = dbContext; } public string GetName() { return "AZRNG"; } /// public async Task GetDetailsAsync(string account) { return await _dbContext.Set ().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
/// /// 查询用户详情 /// /// /// [HttpGet] public async Task > 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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