根据文档,当我像下面这样配置 DbContext 时,DI 在范围内注册它(每个 http 请求)
services.AddEntityFramework()
.AddSqlServer()
.AddDbContext<DBData>(options => {
options.UseSqlServer(Configuration["Data:DefaultConnection:ConnectionString"]);
}
);
当我尝试在另一个线程中访问它时出现问题。
public class HomeController : Controller
{
private readonly DBData _context;
public HomeController(DBData context)
{
_context = context;
}
public IActionResult StartInBackground()
{
Task.Run(() =>
{
Thread.Sleep(3000);
//System.ObjectDisposedException here
var res = _context.Users.FirstOrDefault(x => x.Id == 1);
});
return View();
}
}
我想为每次调用 (AddTransition) 配置 DbContext 创建。这将使我有可能编写下一个代码
public void ConfigureServices(IServiceCollection services)
{
services.AddEntityFramework()
.AddSqlServer()
.AddDbContext<DBData>(options => {
//somehow configure it to use AddTransient
options.UseSqlServer(Configuration["Data:DefaultConnection:ConnectionString"]);
}
);
services.AddTransient<IUnitOfWorkFactoryPerCall, UnitOfWorkFactory>();
services.AddScoped<IUnitOfWorkFactoryPerRequest, UnitOfWorkFactory>();
services.AddMvc();
}
public interface IUnitOfWorkFactoryPerCall : IUnitOfWorkFactory { }
public interface IUnitOfWorkFactoryPerRequest : IUnitOfWorkFactory { }
public interface IUnitOfWorkFactory : IDisposable
{
DBData Context { get; }
}
public class UnitOfWorkFactory : IUnitOfWorkFactoryPerCall, IUnitOfWorkFactoryPerRequest
{
public UnitOfWorkFactory(DBData context)
{
Context = context;
}
public DBData Context
{
get; private set;
}
public void Dispose()
{
Context.Dispose();
}
}
所以现在如果我想为每个请求创建 DBContext,我将使用 IUnitOfWorkFactoryPerRequest
,当我想在某些后台线程中使用 DBContext 时,我可以使用 IUnitOfWorkFactoryPerCall
.
最佳答案
我的临时解决方案。 我创建了可以“以 transient 方式”创建上下文的单例
public class AppDependencyResolver
{
private static AppDependencyResolver _resolver;
public static AppDependencyResolver Current
{
get
{
if (_resolver == null)
throw new Exception("AppDependencyResolver not initialized. You should initialize it in Startup class");
return _resolver;
}
}
public static void Init(IServiceProvider services)
{
_resolver = new AppDependencyResolver(services);
}
private readonly IServiceProvider _serviceProvider;
public AppDependencyResolver(IServiceProvider serviceProvider)
{
_serviceProvider = serviceProvider;
}
public IUnitOfWorkFactory CreateUoWinCurrentThread()
{
var scopeResolver = _serviceProvider.GetRequiredService<IServiceScopeFactory>().CreateScope();
return new UnitOfWorkFactory(scopeResolver.ServiceProvider.GetRequiredService<DBData>(), scopeResolver);
}
}
然后我在Startup Configure方法中调用init方法
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
AppDependencyResolver.Init(app.ApplicationServices);
//other configure code
}
毕竟我可以在某些后台线程中调用 AppDependencyResolver.Current.CreateUoWinCurrentThread()
。
如果有人能提供更优雅的解决方案,我将不胜感激。
关于c# - EF 7(核心)。像 AddTransient 一样创建 DBContext,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/34952087/