ABP No.12 複數資料庫(DBContext)
ABP (ASP.NET Boilerplate) 應用程式開發框架 No.12 複數資料庫(DBContext)
2019/5/7
參照： https://www.twblogs.net/a/5c23609bbd9eee16b3db438c/
2019/4/30
終於成功呼叫同一支API來使用兩個不同資料庫...
步驟有空再補
總之參考以下範例即可
https://github.com/aspnetboilerplate/aspnetboilerplate-samples/tree/master/MultipleDbContextEfCoreDemo
今天試了一下兩個資料連接字串
同一個專案分別連到不同資料庫
這邊記錄一下步驟以備不時之需
0.測試環境：
本次專案名稱為PlatRazor
因此預設會有一個DB叫做PlatRazorDb
然後我要加入另一個DB=EventCloudDb
1.建立實體：這部分不變
public class Game : Entity
{
public virtual string Name { get; set; }
}
2.建立上下文(DbContext)：
這邊我複製了一份PlatRazorDbContext.cs
重命名PlatRazor=>EventCloud
然後一樣把實體加進去
EventCloudDbContext.cs
public class EventCloudDbContext : AbpDbContext
{
public DbSet<Game> Games { get; set; }
public EventCloudDbContext(DbContextOptions<EventCloudDbContext> options)
: base(options)
{
}
}
這裡就是把你準備要放到另一個資料庫的實體
都加到這個新的DbContext
3.然後是PlatRazorDbContextFactory.cs
這檔案裡面說是用來跑migration指令用的
總之一樣複製後重新命名PlatRazor=>EventCloud
EventCloudDbContextFactory.cs
public class EventCloudDbContextFactory : IDesignTimeDbContextFactory<EventCloudDbContext>
{
public EventCloudDbContext CreateDbContext(string[] args)
{
var builder = new DbContextOptionsBuilder<EventCloudDbContext>();
var configuration = AppConfigurations.Get(WebContentDirectoryFinder.CalculateContentRootFolder());
DbContextOptionsConfigurer.Configure(
builder,
configuration.GetConnectionString(PlatRazorConsts.EventCloudConnectionStringName)
);
return new EventCloudDbContext(builder.Options);
}
}
這裡有一個 PlatRazorConsts.EventCloudConnectionStringName
他在核心層的 PlatRazorConsts.cs
就字串常量，把我們的連結字串名稱加進去
public const string EventCloudConnectionStringName = "EventCloud";
public class PlatRazorConsts
{
public const string LocalizationSourceName = "PlatRazor";
public const string ConnectionStringName = "Default";
public const string EventCloudConnectionStringName = "EventCloud";
}
4.appsettings.json
剛剛既然定義了連接字串的名稱
那當然要用這名子加到連結字串設定裡面
"EventCloudDb": "Server=::1; Database=EventCloudDb;User ID=xxx;Password=xxxxxx;"
{
"ConnectionStrings": {
"Default": "Server=::1; Database=PlatRazorDb;User ID=xxx;Password=xxxxxx;",
"EventCloudDb": "Server=::1; Database=EventCloudDb;User ID=xxx;Password=xxxxxx;"
},
"Logging": {
"IncludeScopes": false,
"LogLevel": {
"Default": "Debug",
"System": "Information",
"Microsoft": "Information"
}
}
}
上一行最後記得加個逗號
5.Startup.cs
根據官方文件其實要設定資料庫就是要從這檔案來設定
//Configure DbContext
services.AddAbpDbContext<PlatRazorDbContext>(options =>
{
DbContextOptionsConfigurer.Configure(options.DbContextOptions, options.ConnectionString);
});
一樣複製原本的重新命名PlatRazor=>EventCloud
public IServiceProvider ConfigureServices(IServiceCollection services)
{
//Configure DbContext
services.AddAbpDbContext<PlatRazorDbContext>(options =>
{
DbContextOptionsConfigurer.Configure(options.DbContextOptions, options.ConnectionString);
});
services.AddAbpDbContext<EventCloudDbContext>(options =>
{
DbContextOptionsConfigurer.Configure(options.DbContextOptions, options.ConnectionString);
});
services.AddMvc(options =>
{
options.Filters.Add(new AutoValidateAntiforgeryTokenAttribute());
});
//Configure Abp and Dependency Injection
return services.AddAbp<PlatRazorWebModule>(options =>
{
//Configure Log4Net logging
options.IocManager.IocContainer.AddFacility<LoggingFacility>(
f => f.UseAbpLog4Net().WithConfig("log4net.config")
);
});
}
6.DbContextOptionsConfigurer.cs
上一步會發現設定部分會找不到對應型別的設定檔
官方文件其實是長這樣
services.AddDbContext<MyDbContext>(options =>
{
options.UseSqlServer(Configuration.GetConnectionString("Default"));
});
但開出來的專案實際是長這樣
DbContextOptionsConfigurer.Configure(options.DbContextOptions, options.ConnectionString);
總之呢他把原本的設定統一移動到 DbContextOptionsConfigurer.cs 來做設定
/* This is the single point to configure DbContextOptions for PlatRazorDbContext */
一樣複製裡頭的內容來重新命名PlatRazor=>EventCloud
public static class DbContextOptionsConfigurer
{
public static void Configure(
DbContextOptionsBuilder<PlatRazorDbContext> dbContextOptions,
string connectionString
)
{
/* This is the single point to configure DbContextOptions for PlatRazorDbContext */
dbContextOptions.UseSqlServer(connectionString);
}
public static void Configure(
DbContextOptionsBuilder<EventCloudDbContext> dbContextOptions,
string connectionString
)
{
dbContextOptions.UseSqlServer("Server=::1; Database=EventCloudDb;User ID=xxx;Password=xxxxxx;");
}
}
這裡我是先寫死連結字串
因為他好像是吃PlatRazorWebModule=>PreInitialize預設的連結字串
Configuration.DefaultNameOrConnectionString = _appConfiguration.GetConnectionString(PlatRazorConsts.ConnectionStringName);
TODO:DbContextOptionsConfigurer.cs改吃appsettings.json
7.migration
簡單來說就是指令都要指定 DbContext
PM> Add-Migration Init -Context PlatRazorDbContext
PM> Update-Database -Context PlatRazorDbContext
PM> Add-Migration Init -Context EventCloudDbContext
PM> Update-Database -Context EventCloudDbContext
8.應用服務層
用起來是跟原本一樣的
public class GameAppService : PlatRazorAppServiceBase,IGameAppService
{
private readonly IRepository<Game> _gameRepository;
public GameAppService(IRepository<Game> gameRepository)
{
_gameRepository = gameRepository;
}
public void CreateGame()
{
_gameRepository.Insert(new Game(){Name = "B"});
}
}
9.動態WebApi或是Controller
如果是WebApi可以直接執行然後訪問測試了
應該是 http://localhost:62114/api/services/app/gameApp/createGame
Controller就要把應用服務注入之後呼叫
public class HomeController : PlatRazorControllerBase
{
private readonly IGameAppService _gameAppService;
public HomeController(IGameAppService gameAppService)
{
_gameAppService = gameAppService;
}
public ActionResult Index()
{
_gameAppService.CreateGame();
return View();
}
public ActionResult About()
{
return View();
}
}
亂打得這樣每次開出首頁就會新增一筆紀錄到資料庫
10.資料庫
沒意外了話到資料庫裡面應該會發現有新資料寫入
原本的DB一樣建立Service來呼叫應該也會正常有資料
11.But,人生中最重要的就是這個But!
在一同一次request調用不同DbContext的service會報錯
System.InvalidOperationException: 'The specified transaction is not associated with the current connection. Only transactions associated with the current connection may be used.'
同一個req會共用同一個連線，另外Unit of Work會建立交易，但跨資料庫無法建立交易的樣子
12.TODO
14 October 2025
