c# - 如何使这段代码变干？

Question

我正在使用 C#/wcf 编写 RESTful 服务，需要在 GET 上放置过滤器。比如要返回多少条记录，也许我想按某些东西进行过滤等等。考虑以下代码:

[WebGet(UriTemplate = "/devices/{DeviceId}/positions")]
        public List<GPSPosition> GetDevicePositions(string deviceId)
        {
            //Lookup device:
            using (var context = new MobileModelContext(ContextManager.AccountGKey.Value))
            {
                var d = context.Devices.Where(aa => aa.DeviceId == deviceId).FirstOrDefault();
                if (d == null)
                {
                    outgoingResponse.StatusCode = HttpStatusCode.NotFound;
                    outgoingResponse.StatusDescription = "Device not found";
                    return null;
                }

                var query = from p in context.Positions
                            where p.DeviceKey.Equals(d.DeviceKey)
                            select new GPSPosition
                            {
                                PositionGKey = p.PositionGKey,
                                Latitude = p.Latitude,
                                Longitude = p.Longitude,
                                Speed = p.Speed,
                                Accuracy = p.Accuracy,
                                Altitude = p.Altitude,
                                GPSTime = p.GPSTime,
                                DeviceTime = p.DeviceTime
                            };

                return query.ToList();
            }
        }

        [WebGet(UriTemplate = "/devices/{DeviceId}/positions?RecordCount={RecordCount}")]
        public List<GPSPosition> GetDevicePositions2(string deviceId, int recordCount)
        {
            //Lookup device:
            using (var context = new MobileModelContext(ContextManager.AccountGKey.Value))
            {
                var d = context.Devices.Where(aa => aa.DeviceId == deviceId).FirstOrDefault();
                if (d == null)
                {
                    outgoingResponse.StatusCode = HttpStatusCode.NotFound;
                    outgoingResponse.StatusDescription = "Device not found";
                    return null;
                }

                var query = from p in context.Positions
                            where p.DeviceKey.Equals(d.DeviceKey)
                            select new GPSPosition
                            {
                                PositionGKey = p.PositionGKey,
                                Latitude = p.Latitude,
                                Longitude = p.Longitude,
                                Speed = p.Speed,
                                Accuracy = p.Accuracy,
                                Altitude = p.Altitude,
                                GPSTime = p.GPSTime,
                                DeviceTime = p.DeviceTime
                            };

                return query.Take(recordCount).ToList();
            }
        }

很多重复。我可以将代码移动到其他函数中，但我仍然有 2 个模板，我有 2 个函数。有什么方法可以为/positions/制作 1 个模板来覆盖所有可能的“？”场景？

Answer 1

Take enumerates source and yields elements until count elements have been yielded or source contains no more elements.

自 Take(n)返回最多 n 个项目，但如果可用的项目较少，您可以重写:

  public List<GPSPosition> GetDevicePositions(string deviceId)
  {
    return GetDevicePositions2(deviceId, int.MaxValue)
  }

然后将返回所有项目。