在网格视图控件中查找控件

Question

I know there are alot of questions&answers about this but non of them works for me

Trying to populate this Drop Down List via a function in code behind:

This drop down list is for Images names, when a user choose one and clicks the "Update" link button in the Grid View I need to insert a suffix to the image name (for the path), so if the user choose an image name from the list the update button it will actually update the fileName + insert at the beginning the path, so it would be

../images/gary.jpg

for the name gary.

aspx page

 <asp:TemplateField>
                <EditItemTemplate>                      
                        <asp:DropDownList ID="ddlImages" runat="server">
                        <Items>
                            <asp:ListItem Text="Choose" Value="" />
                        </Items>
                    </asp:DropDownList>
                </EditItemTemplate>
                ...

code behind

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            DropDownList ddlImages = (e.Row.FindControl("ddlImages") as DropDownList);
            ShowImages(ddlImages);

        }
}

"ddlImages" is null, how can I find him?

---

Managed to find the drop down list like that:

if (e.Row.RowType == DataControlRowType.DataRow)
        {
            if ((e.Row.RowState & DataControlRowState.Edit) > 0)
            {
                DropDownList ddlImages = (DropDownList)e.Row.FindControl("ddlImages");
                ddlImages.DataSource = GetImages();
                ddlImages.DataBind();
            }
        }

Now i am facing another problem, in the aspx i have an "UpdateCommand" which take parameters and try to update the database. The problem- it need to take the dropDownList chosen value but instead it take: "" how can i change it to take the value that the user choose in the dropDownList

aspx page

    UpdateCommand="UPDATE [investigator] SET [name] = @name, [area] = @area, [country] = @country,     [picture] = @picture, [review] = @review WHERE [Id] = @Id">

 <UpdateParameters>
            <asp:Parameter Name="name" Type="String" />
            <asp:Parameter Name="area" Type="String" />
            <asp:Parameter Name="country" Type="String" />
            <asp:Parameter Name="picture" Type="String" />
            <asp:Parameter Name="review" Type="String" />
            <asp:Parameter Name="Id" Type="Int32" />
        </UpdateParameters>

Meaning- I have to change

<asp:Parameter Name="picture" Type="String" />

to drop down list selected value. How can I achieve that?

Answer 1

Regarding your question about the update Parameter, you should use the ControlParameter instead of general Parameter. Try replacing the Parameter Definition for the Dropdown list with following code.

<asp:ControlParameter Name="picture" ControlID="ddlImages" 
    PropertyName="SelectedValue" Type="String" />

UPDATE What you can do as alternate is,

Change the parameter back to

<asp:Parameter Name="picture" Type="String" />

Add RowUpdating event handler to the gridview In the RowUpdating command set the data source parameter based on the selected value as below

protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{

GridViewRow row = GridView1.Rows[e.RowIndex];
DropDownList ddlImages=  row.FindControl("ddlImages") as DropDownList;
SqlDataSource1.UpdateParameters["picture"].DefaultValue = ddlImages.SelectedValue;
}