c# - .NET Core 6 将数据库上下文注入(inject)单例服务

Question

当我尝试在我的应用程序的一个单例服务中使用数据库上下文时遇到问题。

应用.cs

...
var service = builder.Services;
service.AddDbContext<MyDBContext>(options => options.UseSqlite(connectionString));
service.AddSingleton<MyMonitorManager>();
...

MyDBContext.cs

public class MyDBContext : ApiAuthorizationDbContext<ApplicationUser>
  {
    public DroneDBContext(...): base(options, operationalStoreOptions){}
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder){}
    protected override void OnModelCreating(ModelBuilder modelBuilder){}
  }

MyMonitorManager.cs

public class MyMonitorManager {
   private readonly MyDBContext _databaseManager;
   ...
}

有错误:

Cannot consume scoped service 'MyController.MyDBContext' from singleton 'MyController.Service.MyMonitorManager'.

我尝试在这里搜索并考虑这样使用:

MyDBContext dbContext = new MyDBContext();
service.AddSingleton(new MyMonitorManager(dbContext));

但不确定在 .NET 6 中我应该怎么做

Answer 1

您可以在单例类中使用 IServiceScopeFactory 来创建新范围，然后从中获取数据库上下文引用:

public class MyMonitorManager {
    private readonly IServiceScopeFactory _scopeFactory;
 
     public MyMonitorManager(IServiceScopeFactory _scopeFactory)
     {
        _scopeFactory = scopeFactory;
     }
 
     public SomeMethod()
     {
        using (var scope = _scopeFactory.CreateScope())
        {
            var db = scope.ServiceProvider.GetRequiredService<MyDBContext>();
            ...
        }
     }
}