使用linq排序網格視圖列

Question

我將數據綁定到模板字段中的gridview，如：

  <asp:TemplateField HeaderText="Business Objective" SortExpression="BusinessObjective.BusinessObjectiveText">
     <ItemTemplate>
        <asp:Label ID="lblBusinessObjectiveText" runat="server" Text='<%#DataBinder.Eval(Container.DataItem, "BusinessObjective.BusinessObjectiveText") %>'></asp:Label>
     </ItemTemplate>
  </asp:TemplateField>

在后面的代碼中，我只是將列表綁定到網格視圖：

    gvBussinessRisks.DataSource = this.BusinessRiskList;
    gvBussinessRisks.DataBind();

列表的類型為“ BusinessRisk”。 實體結構就像

public class BusinessRisk
{
    public BusinessRisk()
    {
        BusinessObjective BusinessObjective = new BusinessObjective();
    }

    public int? BusinessRiskId { get; set; }
    public int ObjectiveId { get; set; }
    public string BusinessRiskText { get; set; }
    public string Description { get; set; }
    public bool IsActive { get; set; }
    public long ActionedBy { get; set; }
    public long? DelegatedTo { get; set; }
    public int? LastLogId { get; set; }
    public int AppOwnerId { get; set; }

    public BusinessObjective BusinessObjective { get; set; }
}

我的BusinessObjective類具有名為“ BusinessObjectiveText”的屬性，該屬性將綁定到網格視圖中的某一列。

但是，當我嘗試對此列進行排序時，我得到了錯誤。

我的排序事件類似於：

List<BusinessRisk> sortedList = this.BusinessRiskList;

    sortedList.Sort(new GenericComparer<BusinessRisk>(e.SortExpression, (SortDirection)Enum.Parse(typeof(SortDirection), GetSortDirection(e.SortExpression))));
    gvBussinessRisks.DataSource = sortedList;
    gvBussinessRisks.DataBind();

而“ GenericComparer”類是：

public class GenericComparer<T> : IComparer<T>
{
    private string sortExpression;
    private SortDirection sortDirection;
    public GenericComparer(string sortExpression, SortDirection sortDirection)
    {
        this.sortExpression = sortExpression;
        this.sortDirection = sortDirection;
    }

    public int Compare(T x, T y)
    {
        PropertyInfo propertyInfo = typeof(T).GetProperty(sortExpression);
        IComparable obj1 = (IComparable)propertyInfo.GetValue(x, null);
        IComparable obj2 = (IComparable)propertyInfo.GetValue(y, null);


        if (SortDirection == SortDirection.Ascending)
        {
            if (obj1 != null)
                return obj1.CompareTo(obj2);
            return 0;
        }
        else
        {
            if (obj1 != null)
                return obj2.CompareTo(obj1);
            return 0;
        }
    }

    public SortDirection SortDirection
    {
        get { return this.sortDirection; }
        set { this.sortDirection = value; }
    }


}

當我嘗試按GenericComparer類中的方法對此列進行排序時出現錯誤（方法：比較），我將propertyInfo獲取為null 。 如果我使用BusinessRisk屬性進行排序，則排序會正確進行，但是在這里，我嘗試使用BussinessObjective類的屬性之一進行排序。

我嘗試了Google，但沒有得到任何解決方案。

Answer 1

終於，經過Google的大量努力和小小的頭腦風暴，我得到了使用Dynamic Linq解決方案。

我放棄了GenericComparer類，只是在Sorting事件中編寫了以下代碼

string sortColumn = e.SortExpression;
    IQueryable<BusinessRisk> sortedList = (from p in this.BusinessRiskList
                                           select new BusinessRisk
                                           {
                                               BusinessRiskText = p.BusinessRiskText,
                                               IsActive = p.IsActive,
                                               Description = p.Description,
                                               BusinessObjective = new BusinessObjective { BusinessObjectiveText = p.BusinessObjective.BusinessObjectiveText }
                                           }).AsQueryable().OrderBy(e.SortExpression);




    this.BusinessRiskList = sortedList.ToList<BusinessRisk>();
    gvBussinessRisks.DataSource = sortedList;
    gvBussinessRisks.DataBind();

它對我來說非常完美。

謝謝所有嘗試幫助我的人。