Thread: SelectedValue from dependant dropdownlist

I have 2 dropdownlist controls on my web form page. The page content sits inside an update panel on my master page.

When one dropdown is changed, the items in the other dropdown are populated based on the selection made. This is done via a web service call.

When I then call a button click event, no value is returned by my dependent dropdown control.

Code:

                   <li style="clear: both;">
                            <asp:Label ID="lblCategory" runat="server" Text="Product Category" />
                            <span class="red bold size_12" style="text-align: left; width: 5px; cursor: help;"
                                title="Required">*</span>
                            <asp:DropDownList ID="ddlCategory" runat="server" CssClass="blue_333399 size_9 textbox"
                                DataValueField="id" DataTextField="category" />
                            <asp:RequiredFieldValidator ID="rfvCategory" runat="server" ControlToValidate="ddlCategory"
                                ErrorMessage="Please select the category" Display="None" EnableClientScript="true"
                                ValidationGroup="evalproduct" />
                        </li>
                        <li style="clear: both;">
                            <asp:Label ID="lblReceptor" runat="server" Text="Product Receptor" />
                            <span class="red bold size_12" style="text-align: left; width: 5px; cursor: help;"
                                title="Required">*</span>
                            <asp:DropDownList ID="ddlReceptor" runat="server" CssClass="blue_333399 size_9 textbox" style="display:none;" />
                            <div id="pHReceptor" class="blue_333399 size_9" style="line-height:23px;">Please select a product category</div>
                        </li>

I have also overridden the Render event to prevent Event Validation problems.

Code:

    protected override void Render(HtmlTextWriter writer)
    {
        this.ddlReceptor.DataSource = Receptor.GetAllReceptorList();
        this.ddlReceptor.DataValueField = "id";
        this.ddlReceptor.DataTextField = "receptor";
        this.ddlReceptor.DataBind();
        this.ddlReceptor.Items.Add(new ListItem("None", "0"));
        base.Render(writer);
    }

In my button click event though, ddlReceptor.SelectedValue is coming back blank.

Any ideas?

OK. I just scrapped the web service population even though the rendering is slightly better and just went for the OnSelectedIndexChanged on the ddlCategory control.

btw, the rendering is better because I also have FCKEditor controls on my page. Using OnSelectedIndexChanged causes a postback that refereshes the FCKeditors. Using the web service stops this, but I guess I'll just have to live with it...