在模板化控件中实现级联DropDownList绑定

时间:2011-07-19 15:38:17

标签: asp.net drop-down-menu formview

我的表单上有2个DropDownList控件,第二个控件使用第一个SelectedValue作为其绑定参数之一。

两个DropDownList控件都在FormView.InsertItemTemplate中,SelectedValue属性使用绑定表达式绑定到FormView的数据源。

第一次FormView在插入模式下呈现时,一切正常。问题是在第一个AutoPostBack的{​​{1}}之后,DropDownList没有(重新)绑定,但是自第二个FormView ControlParameter以来已更改,它已绑定(按预期),但在第二个DDL的绑定表达式上发生异常,我假设,因为DropDownList没有绑定该传递:

  

System.InvalidOperationException:数据绑定方法,如Eval(),   XPath()和Bind()只能在数据绑定的上下文中使用   控制。

这是标记:

FormView

我的问题是:使这项功能有效的最佳方法是什么?是否可以将两个DDL保留在模板中?我宁愿避免使用AJAX工具包或其他客户端解决方案。

4 个答案:

答案 0 :(得分:8)

当我们在像DetailsView/FormView这样的数据绑定控件中使用级联下拉列表时,这是一个问题,我已经多次面对它了。您必须从第二个下拉列表SelectedValue='<%# Bind("AttorneyID") %>'中删除绑定表达式,然后它才能正常工作。

其次,如果删除Binding表达式,则必须在FormView ItemInserting事件中手动传递值。 e.g。

 protected void frmAsset_ItemInserting(object sender, FormViewInsertEventArgs e)
 {
    eValues["AttorneyID"] = ((DropDownList)((FormView)sender).FindControl("ddlAttorny")).SelectedValue;
 }

答案 1 :(得分:4)

实际上我发布这个答案,万一其他人像我一样被卡住了。 穆罕默德·阿赫塔尔所说的完美无缺,但我找到了一个更简单的解决方案 在

<asp:DropDownList ID="ddlAttorney" runat="server" DataSourceID="dsAttorney" DataValueField="AttorneyID" DataTextField="AttorneyNameWithCount" SelectedValue='<%# Bind("AttorneyID") %>'>

Bind("AttorneyID")更改为DataBinder.Eval (Container.DataItem, "AttorneyID")
它完美无缺! 编辑:我的示例代码:

<asp:Content ID="Content3" ContentPlaceHolderID="BodyContent" runat="Server">
<asp:DetailsView ID="dv" runat="server" Height="50px" DataSourceID="ODS" DefaultMode="Insert"
    AutoGenerateRows="False" OnItemCommand="dv_ItemCommand" OnItemInserted="dv_ItemInserted"
    DataKeyNames="Id" OnItemUpdated="dv_ItemUpdated" CssClass="DetailsView" 
    >
    <Fields>
        <asp:TemplateField HeaderText="Page Name:">
            <ItemTemplate>
                <asp:Label ID="txtPageName" runat="server" Text="<%#Bind('PageName') %>" />
            </ItemTemplate>
            <EditItemTemplate>
                <asp:TextBox ID="txtPageName" runat="server" Text="<%#Bind('PageName') %>" />
            </EditItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Parent:">
            <ItemTemplate>
                <asp:Label ID="txtParentPageName" runat="server" Text='<%#Bind("ParentPageName") %>' />
            </ItemTemplate>
            <EditItemTemplate>
                <asp:DropDownList runat="server" ID="lstParentPage" DataSourceID="ParentPageODS"
                    AppendDataBoundItems="true" DataTextField="PageName" DataValueField="Id" SelectedValue="<%#Bind('ParentPage') %>"
                    AutoPostBack="True">
                    <asp:ListItem Text="-Root-" Value="" />
                </asp:DropDownList>
            </EditItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="After...">
            <ItemTemplate>
                <asp:Label ID="txtPreviousPage" runat="server" Text='<%#Bind("PageOrder") %>' />
            </ItemTemplate>
            <EditItemTemplate>
                <asp:DropDownList runat="server" ID="lstPageOrder" AppendDataBoundItems="true" DataTextField="PageName" DataSourceID="PageOrderODS" DataValueField="PageOrder"  EnableViewState="False" SelectedValue='<%# DataBinder.Eval (Container.DataItem, "PageOrder") %>'>
                    <asp:ListItem Text="-First-" Value="" />
                </asp:DropDownList>
                <asp:ObjectDataSource ID="PageOrderODS" runat="server" SelectMethod="SelectByParent"
                    TypeName="SirM2X.Pages">
                    <SelectParameters>
                        <asp:ControlParameter ControlID="lstParentPage" Name="ParentPage" PropertyName="SelectedValue" />
                    </SelectParameters>
                </asp:ObjectDataSource>
            </EditItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Dummy Page?">
            <ItemTemplate>
                <asp:Label runat="server" ID="txtDummyPage" Text="<%#Bind('IsDummyText') %>" />
            </ItemTemplate>
            <EditItemTemplate>
                <asp:CheckBox ID="chkIsDummy" runat="server" Checked="<%#Bind('IsDummy') %>" />
            </EditItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField ShowHeader="False">
            <EditItemTemplate>
                <asp:Button ID="btnUpdate" runat="server" CausesValidation="True" CommandName="Update"
                    Text="<%$Resources:Resources, Update %>" />
                &nbsp;<asp:Button ID="btnCancel" runat="server" CausesValidation="False" CommandName="Cancel"
                    Text="<%$Resources:Resources, Cancel %>" />
            </EditItemTemplate>
            <InsertItemTemplate>
                <asp:Button ID="btnInsert" runat="server" CausesValidation="True" CommandName="Insert"
                    Text="<%$Resources:Resources, Insert %>" />
                &nbsp;<asp:Button ID="btnCancel" runat="server" CausesValidation="False" CommandName="Cancel"
                    Text="<%$Resources:Resources, Cancel %>" />
            </InsertItemTemplate>
            <ItemTemplate>
                <asp:Button ID="btnEdit" runat="server" CausesValidation="False" CommandName="Edit"
                    Text="<%$Resources:Resources, Edit %>" />
            </ItemTemplate>
        </asp:TemplateField>
    </Fields>
</asp:DetailsView>
<asp:ObjectDataSource ID="ODS" runat="server" DeleteMethod="DeleteRow" InsertMethod="InsertRow"
    SelectMethod="SelectRow" TypeName="SirM2X.Pages" UpdateMethod="UpdateRow" OnInserting="ODS_Inserting"
    OnUpdating="ODS_Updating">
    <DeleteParameters>
        <asp:Parameter Name="Id" Type="Int32" />
    </DeleteParameters>
    <InsertParameters>
        <asp:Parameter Name="PageName" Type="String" />
        <asp:Parameter Name="CreatedBy" Type="String" />
        <asp:Parameter Name="ParentPage" Type="Int32" />
        <asp:Parameter Name="PageOrder" Type="Int32" />
        <asp:Parameter Name="IsDummy" Type="Boolean" />
    </InsertParameters>
    <SelectParameters>
        <asp:QueryStringParameter Name="Id" QueryStringField="ID" Type="Int32" />
    </SelectParameters>
    <UpdateParameters>
        <asp:Parameter Name="Id" Type="Int32" />
        <asp:Parameter Name="PageName" Type="String" />
        <asp:Parameter Name="ParentPage" Type="Int32" />
        <asp:Parameter Name="PageOrder" Type="Int32" />
        <asp:Parameter Name="IsDummy" Type="Boolean" />
        <asp:Parameter Name="DeleteState" Type="Boolean" />
    </UpdateParameters>
</asp:ObjectDataSource>
<asp:ObjectDataSource ID="ParentPageODS" runat="server" SelectMethod="SelectAll"
    TypeName="SirM2X.Pages"></asp:ObjectDataSource>

答案 2 :(得分:2)

这可能会有点晚,但迟到总比没有好:

Protected Sub DetailsView1_ItemUpdating(sender As Object, e As System.Web.UI.WebControls.DetailsViewUpdateEventArgs) Handles DetailsView1.ItemUpdating
  e.NewValues("AtendeeSubType") = DirectCast(DirectCast(sender, DetailsView).FindControl("dropdownlist3"), DropDownList).SelectedValue
End Sub

我为详细视图的事件ItemUpdating测试了这个,但我认为它适用于表单视图,只需切换所需的部分即可。

编辑:您可以查看此参考: http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.detailsview.itemupdating.aspx

答案 3 :(得分:1)

我是这样做的......

<asp:SqlDataSource ID="sqldsDDPlant" runat="server" ConnectionString="<%$ ConnectionStrings:SeedTrackerConnectionString %>" 
    SelectCommand="SELECT * FROM [Plant] ORDER BY [Plant]"></asp:SqlDataSource>

<asp:SqlDataSource ID="sqldsDDType" runat="server" ConnectionString="<%$ ConnectionStrings:SeedTrackerConnectionString %>" 
    SelectCommand="SELECT * FROM [Type] ORDER BY [Type]" FilterExpression="PLID = '{0}'">
        <FilterParameters>
            <asp:ControlParameter Name="plantParam" ControlID="DVSeedTracker$ddPlant" PropertyName="SelectedValue" />
        </FilterParameters>  
</asp:SqlDataSource>

        <asp:TemplateField HeaderText="Plant">
            <InsertItemTemplate>
                <asp:DropDownList ID="ddPlant" runat="server" AutoPostBack="true" SelectedValue='<%# Bind("PLID") %>'
                 DataSourceID="sqldsDDPlant"  DataTextField="Plant" DataValueField="PLID" AppendDataBoundItems="True">
                    <asp:ListItem></asp:ListItem>
                </asp:DropDownList>
                 <asp:RequiredFieldValidator
                    id="RequiredFieldValidator2"
                    runat="server"
                    ControlToValidate="ddPlant"
                    Display="Static"
                    ErrorMessage="*Required" CssClass="RequiredField" />                
            </InsertItemTemplate>
        </asp:TemplateField>

        <asp:TemplateField HeaderText="Type">
            <InsertItemTemplate>
                <asp:DropDownList ID="ddType" runat="server"
                DataSourceID="sqldsDDType"  DataTextField="Type" DataValueField="TYPID" AppendDataBoundItems="False">
                    <asp:ListItem></asp:ListItem>
                </asp:DropDownList>
                    <asp:RequiredFieldValidator
                    id="RequiredFieldValidator3"
                    runat="server"
                    ControlToValidate="ddType"
                    Display="Static"
                    ErrorMessage="*Required" CssClass="RequiredField" />                                   
            </InsertItemTemplate>
        </asp:TemplateField>