Question

我正在构建一个Web应用程序，其中将有很多控制器及其相应的操作方法。

我想将每个异常保存在数据库中，因此我创建了 ExceptionService（在其中注入了DbContext）。

让我们说这是我的控制器的一般形式：

[Route("api/[controller]")]
[ApiController]
public class UserController : ControllerBase
{
    private readonly UserManager userManager;
    private readonly IExceptionService exceptionService;

    public UserController(UserManager userManager, IExceptionService exceptionService)
    {
        this.userManager = userManager;
        this.exceptionService = exceptionService;
    }

    [HttpPost]
    public async Task<IActionResult> Post([FromBody] User user)
    {

        try
        {
            //some code
        }
        catch (Exception e)
        {
            exceptionService.Save(e);
            //some code
        }
    }
}

为了避免那么多try-catch块，我决定创建一个看起来像这样的过滤器：

public class ApiExceptionFilterAttribute : ExceptionFilterAttribute
{
    private readonly IExceptionService exceptionService;

    public ApiExceptionFilterAttribute(IExceptionService exceptionService)
    {
        this.exceptionService = exceptionService;
    }

    public override void OnException(ExceptionContext context)
    {
        Exception e = context.Exception;
        exceptionService.Save(e);

        //some code
    }
}

StartUp.cs中ConfigureServices方法中的代码如下（为简单起见删除了一些代码）：

services
    .AddMvc()
    .SetCompatibilityVersion(CompatibilityVersion.Version_2_1)
    .AddJsonOptions(options => options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore);

services
   .AddDbContext<AppDbContext>(options => options.UseSqlServer(Configuration.GetConnectionString("Default")));

services.AddScoped<UserManager>();
services.AddScoped<SignInManager>();


services.AddScoped<IExceptionService, ExceptionService>();


services.AddSingleton<IConfigureOptions<MvcOptions>, ConfigureMvcOptions>();

ConfgureMvcOptions类如下：

public class ConfigureMvcOptions : IConfigureOptions<MvcOptions>
{
    private readonly IExceptionService exceptionService;

    public ConfigureMvcOptions(IExceptionService exceptionService)
    {
        this.exceptionService = exceptionService;
    }

    public void Configure(MvcOptions options)
    {
        options.Filters.Add(new ApiExceptionFilterAttribute(exceptionService));
    }
}

运行此应用程序时，出现以下错误：

System.InvalidOperationException: 'Cannot consume scoped service 'SmartWay.Services.IExceptionService' from singleton 'Microsoft.Extensions.Options.IConfigureOptions`1[Microsoft.AspNetCore.Mvc.MvcOptions]'.'

如果我将IExceptionServcise的生存期更改为瞬态，那么我必须这样做 Dbcontext，然后是DbContextOptions ...看来这不是正确的方法。

那么，我该如何解决这个问题？

Answer 1

要从单例服务解析作用域服务，请尝试_serviceProvider.CreateScope。

请按照以下步骤操作：

ExceptionService

public interface IExceptionService
{
    void Save(Exception ex);
}

public class ExceptionService : IExceptionService
{
    private readonly IServiceProvider _serviceProvider;
    public ExceptionService(IServiceProvider serviceProvider)
    {
        _serviceProvider = serviceProvider;
    }
    public void Save(Exception ex)
    {
        using (var scope = _serviceProvider.CreateScope())
        {
            var _context = scope.ServiceProvider.GetRequiredService<MVCProContext>();
            _context.Add(new Book() { Title = ex.Message });
            _context.SaveChanges();
        }
    }
}

Startup.cs

services.AddSingleton<IExceptionService, ExceptionService>();
services.AddSingleton<IConfigureOptions<MvcOptions>, ConfigureMvcOptions>();

如何将全局捕获的异常保存到数据库中

1 个答案: