在 Edit and Insert Template 中绑定 ListView 中的 DropDown

Question

在我的 ASP.NET 4.5 WebForms 应用程序中，在我的 ListView 中，我试图绑定 DropDownList，但我无法做到。实际上，绑定到 ListView 的模型有一个属性的 UnitdirectionId & 在编辑和插入模板上我想显示所有 UnitDirection table.

的下拉列表

这是我的 EditTempalte：

    <EditItemTemplate>
           <tr>
               <td>
                   <asp:TextBox ID="unitDirTxt" runat="server" Text='<%# Bind("UnitDirectionId") %>'></asp:TextBox>
                    <!-- <asp:DynamicControl runat="server" DataField="UnitDirectionId" ID="UnitDirectionId" Mode="Edit" />  -->
                   <asp:DropDownList ID="unitDirEditDrop" runat="server" ItemType="VincitoreCRMApplication.Models.UnitDirection"
                       DataTextField="DirectionTitle" DataValueField="UnitDirectionId" 
                       SelectMethod="GetUnitDirections"></asp:DropDownList>  
               </td> 
          </tr>

        </EditItemTemplate>

在后面的代码中，

    public IQueryable<UnitDirection> GetUnitDirections()
    {
        return _db.UnitDirections;
    }

现在LsitView的Model有如下属性：

    [Display(Name= "Unit Direction")]
    public int UnitDirectionId { get; set; }

    [ForeignKey("UnitDirectionId")]
    public virtual UnitDirection UnitDirection { get; set; }

现在，UnitDirection 模型：

public class UnitDirection
{
    [ScaffoldColumn(false)]
    public int UnitDirectionId { get; set; }

    [Required]
    [Display]
    public string DirectionTitle { get; set; }
}

我得到的错误是：

 ########## ERRO : An error occurred while executing the command definition. See the inner exception for details. 
 STACK :    at   System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.ExecuteSto reCommands(EntityCommand entityCommand, CommandBehavior behavior)
  at   System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlan.Execute[TResul    tType](ObjectContext context, ObjectParameterCollection parameterValues)
  at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass7.<GetResults>b__6()
  at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass7.<GetResults>b__5()
   at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
  at System.Data.Entity.Core.Objects.ObjectQuery`1.<System.Collections.Generic.IEnumerable<T>.GetEnumerator>b__0()
  at System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()
  at System.Web.UI.WebControls.ListControl.PerformDataBinding(IEnumerable dataSource)
  at System.Web.UI.WebControls.ListControl.OnDataBinding(EventArgs e)
  at System.Web.UI.WebControls.ListControl.PerformSelect()
  at System.Web.UI.WebControls.BaseDataBoundControl.DataBind()
  at System.Web.UI.Control.DataBindChildren()
  at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding)
  at System.Web.UI.Control.DataBind()
  at System.Web.UI.WebControls.ListView.CreateItemsWithoutGroups(ListViewPagedDataSource dataSource, Boolean dataBinding, InsertItemPosition insertPosition, ArrayList keyArray)
  at System.Web.UI.WebControls.ListView.CreateChildControls(IEnumerable dataSource, Boolean dataBinding)
  at System.Web.UI.WebControls.ListView.PerformDataBinding(IEnumerable data)
  at System.Web.UI.WebControls.DataBoundControl.OnDataSourceViewSelectCallback(IEnumerable data)
  at System.Web.UI.DataSourceView.Select(DataSourceSelectArguments arguments, DataSourceViewSelectCallback callback)
   at System.Web.UI.WebControls.DataBoundControl.PerformSelect()
  at System.Web.UI.WebControls.ListView.PerformSelect()
  at System.Web.UI.WebControls.BaseDataBoundControl.DataBind()
  at System.Web.UI.WebControls.BaseDataBoundControl.EnsureDataBound()
  at System.Web.UI.WebControls.BaseDataBoundControl.OnPreRender(EventArgs e)
  at System.Web.UI.Control.PreRenderRecursiveInternal()
  at System.Web.UI.Control.PreRenderRecursiveInternal()
  at System.Web.UI.Control.PreRenderRecursiveInternal()
  at System.Web.UI.Control.PreRenderRecursiveInternal()
  at System.Web.UI.Control.PreRenderRecursiveInternal()
  at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

在 db 中，UnitDirection table 有 3 个项目。

有了上面的下拉列表，我相信我至少应该在下拉列表中得到所有 UnitDirection 的列表。但是在那上面我遇到了错误。然后是在Edit Template中设置选中项

你能帮我确定为什么会出现这个错误吗？？非常感谢任何帮助。

谢谢

Answer 1

正如我们在 Whosebug 聊天中讨论的那样，您在下拉绑定方法中遇到以下错误。

System.InvalidOperationException: There is already an open DataReader associated with this Command which must be closed first.

请在您的 web.config 连接字符串中添加 MultipleActiveResultSets=true 以解决您的问题。

Server=.\SQLEXPRESS;Database=master;Integrated Security=SSPI;
MultipleActiveResultSets=true;

要获取 UnitDirection 值，您需要编写一种方法，如下所示，return UnitDirection 标题为 return 类型。

public string getUnitDirectionTitle(int fiUnitDirectionId)
{
    return UnitDirection.Where(c => c.UnitDirectionId == fiUnitDirectionId);
}

在 ItemDataBound 事件中调用上述方法后，

TextBox.Text = getUnitDirectionTitle(loItem.UnitDirectionId);

如果您有任何问题，请告诉我。

在 Edit and Insert Template 中绑定 ListView 中的 DropDown

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