何时引发异常?何时处理异常(服务层、控制器)的位置

我重写了我的问题，因为我认为它太罗嗦了，也许我想要实现的目标已经丢失了。

我在记事本中编写了这段代码，所以它可能有错误，有些东西可能不太好，但它是为了说明我看到我的选择是什么。

// I wrap all code send back from service layer to controller in this class.
  public class ResponseResult
    {
        public ResponseResult()
        {
            Errors = new Dictionary<string, string>();
            Status = new ResponseBase();
        }
        public void AddError(string key, string errorMessage)
        {
            if (!Errors.ContainsKey(key))
            {
                Errors.Add(key, errorMessage);
            }
        }
        public bool IsValid()
        {
            if (Errors.Count > 0)
            {
                return false;
            }
            return true;
        }

        public Dictionary<string, string> Errors { get; private set; }

        public ResponseBase Status { get; set; }
    }
    public class ResponseResult<T> : ResponseResult
    {
        public T Response { get; set; }
    }
    public class ResponseBase
    {
        public HttpStatusCode Code { get; set; }
        public string Message { get; set; }
    }

选项 1(我现在使用的(

//controller
    public HttpResponseMessage GetVenue(int venueId)
            {
                if (venueId == 0)
                {
                    ModelState.AddModelError("badVenueId", "venue id must be greater than 0");
                if (ModelState.IsValid)
                {
                    var venue = venueService.FindVenue(venueId);
                    return Request.CreateResponse<ResponseResult<Venue>>(venue.Status.Code, venue);
                }
                // a wrapper that I made to extract the model state and try to make all my request have same layout.
                var responseResult = new ResponseResultWrapper();
                responseResult.Status.Code = HttpStatusCode.BadRequest;
                responseResult.Status.Message = GenericErrors.InvalidRequest;
                responseResult.ModelStateToResponseResult(ModelState);
                return Request.CreateResponse<ResponseResult>(responseResult.Status.Code, responseResult);
            }
// service layer        
             public ResponseResult<Venue> FindVenue(int venueId)
            {
                ResponseResult<Venue> responseResult = new ResponseResult<Venue>();
                try
                {
                    // I know this check was done in the controller but pretend this is some more advanced business logic validation.
                    if(venueId == 0)
                    {
                       // this is like Model State Error in MVC and mostly likely would with some sort of field.
                       responseResult.Errors.Add("badVenueId", "venue id must be greater than 0");
                       responseResult.Status.Code = HttpStatusCode.BadRequest;
                    }
                    var venue = context.Venues.Where(x => x.Id == venueId).FirstOrDefault();
                    if(venue == null)
                    {
                        var foundVenue = thirdPartyService.GetVenue(venueId);
                        if(foundVenue == null)
                        {
                           responseResult.Status.Code = HttpStatusCode.NotFound;
                           responseResult.Status.Message = "Oops could not find Venue";
                           return responseResult;
                        }
                        else
                        {
                           var city = cityService.FindCity(foundVenue.CityName);
                           if(city == null)
                           { 
                              city = cityService.CreateCity(foundVenue.CityName);
                              if(city.Response == null)
                              {
                                 responseResult.Status.Code = city.Status.Code;
                                 responseResult.Status.Message = city.Status.Message;
                                 return responseResult;
                              }
                              CreateVenue(VenueId, city.Response, foundVenue.Name);
                               responseResult.Status.Code = HttpStatusCode.Ok;
                               // I don't think I would return a success message here as the venue being displayed back to the user should be good enough.
                               responseResult.Status.Message = "";
                               reponseResult.Response = foundVenue;
                           }
                        }
                        return responseResult;
                    }
                }
                catch (SqlException ex)
                {
                    ErrorSignal.FromCurrentContext().Raise(ex);
                    responseResult.Status.Code = HttpStatusCode.InternalServerError;
                    responseResult.Status.Message = GenericErrors.InternalError;
                    // maybe roll back statement here depending on the method and what it is doing.
                }
               // should I catch this, I know it should be if you handle it but you don't want nasty messages going back to the user.
                catch (InvalidOperationException ex)
                {
                    ErrorSignal.FromCurrentContext().Raise(ex);
                    responseResult.Status.Code = HttpStatusCode.InternalServerError;
                    responseResult.Status.Message = GenericErrors.InternalError;
                }
               // should I catch this, I know it should be if you handle it but you don't want nasty messages going back to the user.
                catch (Exception ex)
                {
                    ErrorSignal.FromCurrentContext().Raise(ex);
                    responseResult.Status.Code = HttpStatusCode.InternalServerError;
                    responseResult.Status.Message = GenericErrors.InternalError;
                }
                return responseResult;
            }
// another service layer. 
        // it is ResponseResult<City> and not city because I could have a controller method that directly calls this method.
            // but I also have a case where my other method in another service needs this as well.
            public ResponseResult<City> CreateCity(string CityName)
            {
               ResponseResult<City> responseResult = new ResponseResult<City>();
               try
               {
                   City newCity = new City {  Name = "N" };
                   context.Cities.Add(newCity);
                   context.SaveChanges();
                    responseResult.Status.Code = HttpStatusCode.Ok;
                    responseResult.Status.Message = "City was succesfully added";
               }           
               // same catch statmens like above
               catch (SqlException ex)
                {
                    ErrorSignal.FromCurrentContext().Raise(ex);
                    responseResult.Status.Code = HttpStatusCode.InternalServerError;
                    responseResult.Status.Message = GenericErrors.InternalError;
                    // maybe roll back statement here depending on the method and what it is doing.
                }
                return responseResult;
            }

如您所见，这些方法都包装在状态代码中，因为它们可以直接由公共控制器调用。FindCity(( 和 CreateVenue(( 也可以有这种包装。

选项 2

   public HttpResponseMessage GetVenue(int venueId)
        {
            try
            {
                if (venueId == 0)
                {
                    ModelState.AddModelError("badVenueId", "venue id must be greater than 0");
                if (ModelState.IsValid)
                {
                    var venue = venueService.FindVenue(venueId);
                    return Request.CreateResponse<ResponseResult<Venue>>(HttpSatusCode.Ok, venue);
                }
                // a wrapper that I made to extract the model state and try to make all my request have same layout.
                var responseResult = new ResponseResultWrapper();
                responseResult.Status.Code = HttpStatusCode.BadRequest;
                responseResult.Status.Message = GenericErrors.InvalidRequest;
                responseResult.ModelStateToResponseResult(ModelState);
                return Request.CreateResponse<ResponseResult>(responseResult.Status.Code, responseResult);
            }
            catchcatch (SqlException ex)
            {
               // can't remember how write this and too tried to look up.
               return Request.CreateResponse(HttpStatusCode.InternalServerError;, "something here");
            }
        }
 public Venue FindVenue(int venueId)
        {
            try
            {
                // how to pass back business logic error now without my wrapper?
                if(venueId == 0)
                {
                   // what here?
                }
                var venue = context.Venues.Where(x => x.Id == venueId).FirstOrDefault();
                if(venue == null)
                {
                    var foundVenue = thirdPartyService.GetVenue(venueId);
                    if(foundVenue == null)
                    {
                       // what here?
                    }
                    else
                    {
                       var city = cityService.FindCity(foundVenue.CityName);
                       if(city == null)
                       { 
                          city = cityService.CreateCity(foundVenue.CityName);
                          if(city  == null)
                          {
                             // what here?
                          }
                          CreateVenue(VenueId, city.Response, foundVenue.Name);

                       }
                    }
                    return venue;
                }
            }
            catch (SqlException ex)
            {
                // should there be a try catch here now? 
                // I am guessing I am going to need to have this here if I need to do a rollback and can't do it in the controller
                // throw exception here. Maybe this won't exist if no rollback is needed.
            }
            return null;
        }
        public City CreateCity(string CityName)
        {
           // if it crashes something I guess will catch it. Don't think I need to rollback here as only one statement being sent to database.
            City newCity = new City {  Name = "N" };
            context.Cities.Add(newCity);
            context.SaveChanges();
            return newCity;            
        }

正如您在选项 2 中看到的那样，我可能仍然需要将其包装在 try catch 中进行回滚，并且我不确定如何处理高级业务验证。

此外，捕获控制器中的所有内容并发回香草对象(没有我的包装器(，我不确定如何做细粒度的 HttpStatus 代码(比如 notFound，Create 等(