将列表项添加到下拉列表 [英] Add listitem to a dropdownlist

问题描述

大家好，

我一直试图在我的下拉列表中的项目顶部添加一个列表项.下拉列表绑定了一个数据源. VS忽略了我编写的每段代码.这是我到目前为止尝试过的内容:

Hello all,

I have been trying to add a list item to the top of the items in my drop down list. The drop down list has a data source binded to it. VS ignores every piece of code that I have written. Here what i have tried so far:

ddlRepUserCreated.Items.Insert(0, new ListItem("Please choose a user", String.Empty));

我在设计器中的代码:

My code in the designer:

<asp:DropDownList ID="ddlRepUserCreated" runat="server"

                                    DataSourceID="dsRepUserCreated" DataTextField="Expr1" DataValueField="Expr1">
                                    <asp:ListItem>Please choose a user</asp:ListItem>
                                </asp:DropDownList>
                    <asp:SqlDataSource ID="dsRepUserCreated" runat="server"

                        ConnectionString="<%$ ConnectionStrings:RMA_DBConnectionStringNew %>"

                        SelectCommand="SELECT userFirstName + SPACE(1) + userSurname AS Expr1 FROM RMAUsers">
                    </asp:SqlDataSource>

即使我在设计器中有一个ListItem，我也无法在下拉菜单中说请选择用户".我知道我可以通过将其添加到数据库中来完成此操作，但我不想这样做.你们能告诉我如何添加这个项目吗?预先感谢.

Even I have a ListItem in the designer, i can not get to have an item in my drop down saying "Please choose a user". I know i can accomplish this by adding this to the database but I do not want to do that. Can you guys please advise how i can add this item? Thanks in advance.

推荐答案

ConnectionStrings:RMA_DBConnectionStringNew ％> " SelectCommand =" > < /asp:SqlDataSource >

ConnectionStrings:RMA_DBConnectionStringNew %>" SelectCommand="SELECT userFirstName + SPACE(1) + userSurname AS Expr1 FROM RMAUsers"> </asp:SqlDataSource>

即使我在设计器中有一个ListItem，我也无法在下拉菜单中说请选择用户".我知道我可以通过将其添加到数据库中来完成此操作，但我不想这样做.你们能告诉我如何添加这个项目吗?预先感谢.

Even I have a ListItem in the designer, i can not get to have an item in my drop down saying "Please choose a user". I know i can accomplish this by adding this to the database but I do not want to do that. Can you guys please advise how i can add this item? Thanks in advance.

您好，

您的代码完全符合其要求；).
您将在下拉列表的INDEX 0处插入带有空字符串的新ListItem.

这应该可以工作:
ddlRepUserCreated.Items.Add(请选择一个用户");

无论如何，我会删除您的

Hi,

your code does exactly what it should like ;).
you are inserting a new ListItem with an empty string at INDEX 0 of your dropdownlist.

This should work:
ddlRepUserCreated.Items.Add("Please choose a user");

Anyway I would remove your

<asp:ListItem>Please choose a user</asp:ListItem>
                                </asp:DropDownList>

并从SQL检索数据后，通过代码将其添加(请参见obove items.Add(")).

您的Dropdownlist属性中也缺少AppendDataBoundItems ="true".

问候

and add it through code (see obove items.Add("")) after retrieving Data from SQL.

AppendDataBoundItems="true" is also missing in your Dropdownlist Properties.

Regards

在您的下拉列表标签上添加AppendDataBoundItems="true"

Add AppendDataBoundItems="true" on your dropdownlist tag

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