開篇語

本文主要是回顧下從項目創建到生成數據到數據庫(代碼優先)的全部過程。采用EFCore作為ORM框架。

本次示例環境：vs2019、net5、mysql

創建項目

本次事例代碼是用過vs2019創建的ASP.NET Core Web API項目

可以通過可視化界面創建或者通過命令行創建

dotnet?new?webapi?-o?Net5ByDocker

創建實體類

安裝連接MySQL數據庫組件

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

增加實體類

????[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("主鍵")][StringLength(36)][Required]public?string?Id?{?get;?private?set;?}[Comment("帳號")][StringLength(36)][Required]public?string?Account?{?get;?private?set;?}[Comment("密碼")][StringLength(36)][Required]public?string?Password?{?get;?private?set;?}[Comment("余額")][Column(TypeName?=?"decimal(18,?2)")][Required]public?decimal?Money?{?get;?set;?}[Comment("是否刪除")][Column(TypeName?=?"tinyint(1)")][Required]public?bool?Deleted?{?get;?private?set;?}[Comment("創建人")][StringLength(20)][Required]public?string?Creater?{?get;?private?set;?}[Comment("創建時間")][Required]public?DateTime?CreateTime?{?get;?private?set;?}[Comment("修改人")][StringLength(20)][Required]public?string?Modifyer?{?get;?private?set;?}[Comment("修改時間")][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;}}

這種只是增加實體類類型的一種方式，可能這種看著比較亂，還可以通過OnModelCreating實現，詳情看參考文檔

增加數據庫上下文OpenDbContext

????public?class?OpenDbContext?:?DbContext{public?OpenDbContext(DbContextOptions<OpenDbContext>?options):?base(options){}public?DbSet<User>?Users?{?get;?set;?}}

Startup注入連接數據庫操作

????????????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);}));

生成遷移文件

引用組件

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

遷移命令

add-migration?Init

結果

image.png

要看下生成的遷移文件是否是自己預期的那樣子，也可以在這一步就生成數據庫，命令：Update-Database

數據種子

增加OpenDbSend類，添加數據種子

????public?class?OpenDbSend{///?<summary>///?生成數據庫以及數據種子///?</summary>///?<param?name="dbContext">數據庫上下文</param>///?<param?name="loggerFactory">日志</param>///?<param?name="retry">重試次數</param>///?<returns></returns>public?static?async?Task?SeedAsync(OpenDbContext?dbContext,ILoggerFactory?loggerFactory,int??retry?=?0){int?retryForAvailability?=?retry.Value;try{dbContext.Database.Migrate();//如果當前數據庫不存在按照當前?model?創建，如果存在則將數據庫調整到和當前?model?匹配await?InitializeAsync(dbContext).ConfigureAwait(false);//if?(dbContext.Database.EnsureCreated())//如果當前數據庫不存在按照當前 model創建，如果存在則不管了。//??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>///?初始化數據///?</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("張三",?"123456",?"azrng")).ConfigureAwait(false);}await?context.SaveChangesAsync().ConfigureAwait(false);}}

設置項目啟動時候調用

????????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,?$"項目啟動出錯??{ex.Message}");}}await?host.RunAsync().ConfigureAwait(false);}

生成數據庫

啟動項目，自動生成數據庫

image.png

表結構如下

image.png

如果后期數據庫字段或者結構有變動，可以再次生成遷移文件然后生成數據庫

查詢數據

????///?<summary>///?用戶接口///?</summary>public?interface?IUserService{string?GetName();///?<summary>///?查詢用戶信息///?</summary>///?<param?name="account"></param>///?<returns></returns>Task<User>?GetDetailsAsync(string?account);}///?<summary>///?用戶實現///?</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);}}

一般更推薦建立指定的返回Model類，然后只查詢需要的內容，不直接返回實體類

控制器方法

????????///?<summary>///?查詢用戶詳情///?</summary>///?<param?name="account"></param>///?<returns></returns>[HttpGet]public?async?Task<ActionResult<User>>?GetDetailsAsync(string?account){return?await?_userService.GetDetailsAsync(account).ConfigureAwait(false);}

查詢結果

{"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" }

參考文檔

實體類型：https://docs.microsoft.com/zh-cn/ef/core/modeling/entity-types?tabs=data-annotations

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

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