计算连续记录中的距离

我正在开发一个跟踪燃料的应用程序。每条记录都记录了去加油站的数据。我决定在数据库中存储尽可能少的信息，并在控制器中计算。

这是我的模型:

public class Refuel
{
    #region Properties
        public int id { get; set; }
        public int mileage { get; set; }
        public DateTime date { get; set; }
        public Nullable<double> volume { get; set; }
        public Nullable<double> price { get; set; }
        public Nullable<int> imageId { get; set; }
        public Nullable<int> gasstationId { get; set; }
        public virtual Gasstation Gasstation { get; set; }
        public virtual Image Image { get; set; }
    #endregion
    #region Methods
        public int distance { get; set; }
        [DisplayFormat(DataFormatString = "€ {0:0.00}")]
        public Nullable<double> totalPrice
        {
            get
            {
                return volume * price;
            }
        }
        [DisplayFormat(DataFormatString = "{0:0.00}")]
        public Nullable<double> consumption
        {
            get
            {
                if (distance > 0)
                    return volume / distance * 100;
                else
                    return 0;
            }
        }
        [DisplayFormat(DataFormatString = "{0:0}")]
        public Nullable<double> consumption2
        {
            get
            {
                if (distance > 0)
                    return distance / volume;
                else
                    return 0;
            }
        }
        [DisplayFormat(DataFormatString = "{0:0.00}")]
        public Nullable<double> mileageLeft
        {
            get 
            {
                return volumeLeft * consumption2;
            }
        }
        [DisplayFormat(DataFormatString = "{0:0.00}")]
        public Nullable<double> volumeLeft
        {
            get
            {
                double? d = 45 - volume;
                return d;
            }
        }
    #endregion
}

你可以看到，这里我没有对距离做任何处理。我在详细信息页中计算了一条特定记录的距离。

我现在要做的是在索引页上做一个汇总，汇总距离并计算平均消耗。这些都是相对于距离的，但在这一点上这是一个空字段。

我在索引页上显示所有记录的列表时也遇到了同样的问题。距离和消耗列为空。

在那一点填满距离的最好方法是什么?还是将距离存储在数据库中更好呢?

这是我的索引函数

    [HttpGet]
    [Authorize]
    public ActionResult Index(string sortOrder, int? page)
    {
        ViewBag.CurrentSort = sortOrder;
        ViewBag.NameSortParm = String.IsNullOrEmpty(sortOrder) ? "asc" : "";
        List<Refuel> rf = db.Refuels.ToList();
        var refuels = from t in db.Refuels select t;
        switch (sortOrder)
        {
            case "asc":
                refuels = refuels.OrderBy(q => q.mileage);
                break;
            default:
                refuels = refuels.OrderByDescending(q => q.mileage);
                break;
        }
        // statistieken
        ViewBag.count = rf.Count();
        ViewBag.distance = rf.Sum(q => q.distance);
        ViewBag.volume = rf.Sum(q => q.volume);
        ViewBag.consumption = String.Format("{0:0.0}", rf.Where(q => q.consumption > 0).Average(q => q.consumption));
        ViewBag.consumption2 = String.Format("{0:0.0}", rf.Where(q => q.consumption2 > 0).Average(q => q.consumption2));
        ViewBag.cost = String.Format("{0:c2}", rf.Sum(q => q.totalPrice));
        int pageSize = 10;
        int pageNumber = (page ?? 1);
        return View(refuels.ToPagedList(pageNumber, pageSize));
    }

设法修复了摘要部分，当然，我可以使用最后和第一英里来获得行驶的总距离:

ViewBag.count = tb.Count();
ViewBag.distance = tb.Last().mileage - tb.First().mileage;
ViewBag.volume = tb.Sum(q => q.volume);
ViewBag.consumption = String.Format("{0:0.0}", ViewBag.volume / ViewBag.distance * 100);
ViewBag.consumption2 = String.Format("{0:0.0}", ViewBag.distance / ViewBag.volume);
ViewBag.cost = String.Format("{0:c2}", tb.Sum(q => q.totalPrice));

我现在需要做的就是在索引表中显示每条记录的距离。这是我的index.cshtml中的循环:

@foreach (var item in Model)
{
    <tr>
        <td>
            @Html.ActionLink(Html.DisplayFor(modelItem => item.mileage).ToString(), "Details", new { id = item.id })
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.date)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.distance)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.volume)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.consumption)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.totalPrice)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Gasstation.fullname)
        </td>
    </tr>
}