開篇語
本文主要是回顧下從專案建立到生成資料到資料庫(程式碼優先)的全部過程。採用EFCore作為ORM框架。
本次示例環境：vs2019、net5、mysql
建立專案
本次事例程式碼是用過vs2019建立的ASP.NET Core Web API專案
可以通過視覺化介面建立或者通過命令列建立
dotnet new webapi -o Net5ByDocker
建立實體類
安裝元件
<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("餘額")]
[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("建立人")]
[StringLength(20)]
[Required]
public string Creater { get; private set; }
[Comment("建立時間")]
[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型別的一種方式，可能這種看著比較亂，還可以通過OnModelCreating實現，詳情看參考文件
增加資料庫上下文OpenDbContext
public class OpenDbContext : DbContext
{
public OpenDbContext(DbContextOptions<OpenDbContext> options)
: base(options)
{
}
public DbSet<User> Users { get; set; }
}
Startup注入連線資料庫操作
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);
}));
生成遷移檔案
引用元件
<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
要看下生成的遷移檔案是否是自己預期的那樣子，也可以在這一步就生成資料庫，命令：Update-Database
資料種子
增加OpenDbSend類，新增資料種子
public class OpenDbSend
{
/// <summary>
/// 生成資料庫以及資料種子
/// </summary>
/// <param name="dbContext">資料庫上下文</param>
/// <param name="loggerFactory">日誌</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();//如果當前資料庫不存在按照當前 model 建立，如果存在則將資料庫調整到和當前 model 匹配
await InitializeAsync(dbContext).ConfigureAwait(false);
//if (dbContext.Database.EnsureCreated())//如果當前資料庫不存在按照當前 model建立，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>
/// 初始化資料
/// </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);
}
}
設定專案啟動時候呼叫
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, $"專案啟動出錯 {ex.Message}");
}
}
await host.RunAsync().ConfigureAwait(false);
}
生成資料庫
啟動專案，自動生成資料庫
表結構如下
如果後期資料庫欄位或者結構有變動，可以再次生成遷移檔案然後生成資料庫
查詢資料
/// <summary>
/// 使用者介面
/// </summary>
public interface IUserService
{
string GetName();
/// <summary>
/// 查詢使用者資訊
/// </summary>
/// <param name="account"></param>
/// <returns></returns>
Task<User> GetDetailsAsync(string account);
}
/// <summary>
/// 使用者實現
/// </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，然後只查詢需要的內容，不直接返回實體類
控制器方法
/// <summary>
/// 查詢使用者詳情
/// </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"
}
參考文件
實體型別：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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