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Model具有UnitdirectionId＆amp;属性。在编辑＆amp;插入模板'我想显示所有UnitDirection表的下拉列表。

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Code背后，

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

现在，LsitView的模型具有如下优点：

    [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表有3个项目。

通过上面的下拉，我相信我应该至少得到所有UnitDirection列表中的下拉列表。但就此而言，我遇到了错误。然后在“编辑模板”中设置所选项目。

你能帮我解释一下为什么我会收到这个错误吗？任何帮助都非常感谢。

由于

Answer 1

正如我们在stackoverflow聊天中讨论的那样，您在下拉绑定方法中面临以下错误。

System.InvalidOperationException：已经有一个与此命令关联的打开的DataReader，必须先关闭它。

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，您需要编写一个类似下面的方法并返回UnitDirection标题作为返回类型。

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

在ItemDataBound事件中调用上面的方法之后

TextBox.Text = getUnitDirectionTitle(loItem.UnitDirectionId);

如果您有任何疑问，请与我们联系。

在Edit＆amp;中将ListD中的DropDown绑定在ListView中插入模板

1 个答案: