C# getting selected value from dropdownlist in gri

问题:

How can I change the value of a textbox whenever a dropdownlist within a gridview has its value changed?

On page load, the textbox shows the selected value, but when I change the selection of the dropdownlist, the textbox value doesn't change.

The code is below.

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns = "false">
    <Columns>
        <asp:TemplateField HeaderText="Entry">
            <ItemTemplate>
                <%# Container.DataItemIndex + 1 %>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Duty">
            <ItemTemplate>
                <asp:DropDownList ID="duty" runat="server" OnLoad = "ddl1_load" OnSelectedIndexChanged="duty_SelectedIndexChanged" autopostback="true" EnableViewState="true"></asp:DropDownList>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

The code behind is below.

protected void ddl1_load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        DataTable dt = new DataTable();
        Duty dy = new Duty();
        dt = dy.getdutyid(Convert.ToInt32(dropcontractid.SelectedValue));
        DropDownList ddl = (DropDownList)sender;
        ddl.DataSource = dt;
        ddl.DataTextField = "dutyid";
        ddl.DataValueField = "dutyid";
        ddl.DataBind();
        TextBox1.Text = ddl.SelectedValue;
    }
}

回答1:

You need to use SelectedIndexChanged handler to show selected value:

Markup:

<asp:DropDownList ID="duty" runat="server" OnLoad="ddl1_load" OnSelectedIndexChanged="duty_SelectedIndexChanged"></asp:DropDownList>

Code-behind:

protected void duty_SelectedIndexChanged(object sender, EventArgs e)
{
    GridViewRow gvr = (GridViewRow)(((Control)sender).NamingContainer);   
    DropDownList duty= (DropDownList) gvr.FindControl("duty");
    TextBox1.Text = duty.SelectedItem.Value;
}

回答2:

I had a similar problem using the DropDownLists in GridView. My solution was to adjust the onLoad for the dropdown so that it wouldn't re-write the DropDownList on every post back. This way if there's something there then it won't re-populate it.

protected void dropDownLoad(object sender, EventArgs e)
{
    DropDownList dropDown = sender as DropDownList;
    if (dropDown.SelectedValue == null || dropDown.SelectedValue == "")
    { 
        // Your Code to populate table
    }
}

回答3:

You should look into using data binding instead. You can bind the textbox.Text to the selecteditem.value, this will ensure that proper updating takes place

回答4:

this happens to me once then i code like this... but i didnt use the onLoad attribute, tell me if this works,

 <asp:TemplateField HeaderText="duty" SortExpression="duty">
                                       <EditItemTemplate>
                                      <asp:TextBox ID="duty" runat="server" Text='<%# Bind("duty_Name") %>'></asp:TextBox>
                                    </EditItemTemplate>
                                      <ItemTemplate>
                                           <asp:Label ID="lblduty" runat="server" Text='<%# Eval("duty_Name") %>' />
                                        <asp:DropDownList ID="ddlduty" runat="server" CssClass="dropdownlist" 
                                          OnLoad = "ddl1_load" OnSelectedIndexChanged="duty_SelectedIndexChanged" Visible = "false" 
                                           >
                                        </asp:DropDownList>
                                    </ItemTemplate>


                                        <HeaderStyle Width="5%" />
                                        <ItemStyle HorizontalAlign="Center" />
                                    </asp:TemplateField>