未发现 GridView 中的 ASP.NET 控件存在于后面的代码中 [英] ASP.NET control in GridView not found to exist in code behind

问题描述

我有一个 DropDownList，我想用数据库中的列值填充它.但是，当我尝试在后面的代码中绑定 DropDownList 时，IDE 一直告诉我:

I have a DropDownList that I would like to populate with column values from a DataBase. However, when I try to bind the DropDownList in code behind, the IDE keeps telling me:

当前上下文中不存在名称‘EqpCatDDL’"

"The name 'EqpCatDDL' does not exist in the current context"

我不确定发生了什么，因为我通过其 ID 引用了控件.代码如下:

I am not sure what is going on since I referred to the control by its ID. The following is the code:

aspx:

<asp:GridView ID="Gridview1" runat="server" ShowFooter="true" 
                AutoGenerateColumns="false" 
                >
                <Columns>
                    <asp:BoundField DataField="S/N" HeaderText="S/N" />
                    <asp:TemplateField HeaderText="Item Name">
                        <ItemTemplate>
                            <asp:DropDownList ID="EqpCatDDL" runat="server"></asp:DropDownList>
                        </ItemTemplate>
                    </asp:TemplateField>
                    <asp:TemplateField HeaderText="Description">
                        <ItemTemplate>
                            <asp:DropDownList ID="DescripDDL" runat="server">
                            </asp:DropDownList>
                        </ItemTemplate>
                    </asp:TemplateField>
                    <asp:TemplateField HeaderText="Quantity">
                        <ItemTemplate>
                            <asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
                        </ItemTemplate>
                    </asp:TemplateField>
                    <asp:TemplateField HeaderText="Remarks">
                        <ItemTemplate>
                            <asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>
                        </ItemTemplate>
                        <FooterStyle HorizontalAlign="Right" />
                        <FooterTemplate>
                            <asp:Button ID="ButtonAdd" onclick="ButtonAdd_Click" runat="server" Text="Add New Row" />
                        </FooterTemplate>
                    </asp:TemplateField>
                </Columns>
            </asp:GridView>

c#:

    public void Populate1()
{
    string connString = ConfigurationManager.ConnectionStrings["MyDbConn"].ConnectionString;
    SqlConnection connection = new SqlConnection(connString);

    SqlCommand cmd = new SqlCommand("SELECT EqpCateID, EqpCat FROM EqpCategory", connection);
    cmd.Connection.Open();

    SqlDataReader ddlValues;
    ddlValues = cmd.ExecuteReader();

    EqpCatDDL.DataSource = ddlValues;
    EqpCatDDL.DataValueField = "EqpCateID";
    EqpCatDDL.DataTextField = "EqpCat";
    EqpCatDDL.DataBind();

    cmd.Connection.Close();
    cmd.Connection.Dispose();
}
protected void Page_Load(object sender, EventArgs e)
{
    Populate1(); 
}

IDE 找不到 EqpCatDDL 控件.

The IDE can't find the EqpCatDDL control.

我正在使用以下软件:Visual Studio 2010、Microsoft SQL Server Management Studio 2008

I am using the following: Visual Studio 2010, Microsoft SQL Server Management Studio 2008

我正在使用 Visual Studio 网站

I am working with a Visual Studio website

推荐答案

使用此代码将数据绑定到 dropdown 而不使用 RowDataBound.

Use this code to bound data to dropdown without using RowDataBound.

创建一个函数，将数据绑定到 dropdown 如下，并在 Page_Load 事件中调用它

Create a function that'll bind the Data to dropdown as follow and call it in Page_Load event

Public void fill_gridView_dropDown()
{
    // your connection and query to retrieve dropdown data will go here 
    // this loop will go through all row in GridView
    foreach(GridViewRow row in your_gridView_Name.Rows) {
        DropDownList  dropDown = (DropDownList)row.FindControl("dropDownList_id");
        dropDown.DataSource = dataSource;
        dropDown.DataValueField = "ValueField";
        dropDown.DataTextField = "TextField";
        dropDown.DataBind();
    }
}

请注意，你必须先bind GridView，然后你必须绑定你的下拉框

Please note that you have to bind GridView first, and then you have to bind your dropdown

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