如何在 ASP.NET 中找到嵌套在 div 标签中的子控件

Question

Hi i want to find an image button control which is in a table which is nested in 3 div tags actually it returns null if i use the below code

for (int j = 1; j < 38; j++)
{
    string s = "ib_s" + j;
    ImageButton img = (ImageButton)FindControl(s.ToString());
    if (status[j] == "B")
    {
        img.ImageUrl = "~/graphics/Booked.jpg";
        img.Enabled = false;
    }
    else
    {
        img.ImageUrl = "~/graphics/Available.jpg";
    }
}

as i wanted to find image buttons with id's ib_s1, ib_s2.... and change the image url.

And i use a master page for this page, so please help me.

Answer 1

1. As @Filip Ekberg commented, make sure ImageButton s have runat="server" attribute.

2. If the ImageButton is on Content Page then you cannot find them on the MasterPage 's code behind.

Answer 2

Mark the outer div with runat="server" attribute and search for ImageButton in that div: ImageButton img = containerDivId.FindControl(imageButtonServerID) as ImageButton;

By the way, could you explain your aim? What you want to achieve on this page? As you have a table with 38 elements I suppose that it's would be better to use some data-driven control like Repeater here.

Answer 3

I got using this code from here http://www.asp.net/master-pages/tutorials/control-id-naming-in-content-pages-cs

for (int j = 0; j < 37; j++)
    {
        string s = "ctl00$ContentPlaceHolder1$ib_s" + k;
        ImageButton img = (ImageButton)FindControl(s.ToString());
        if (status[j] == "B")
        {
            img.ImageUrl = "~/graphics/Booked.jpg";
            img.Enabled = false;
        }
        else
        {
            img.ImageUrl = "~/graphics/Available.jpg";
        }
        k++;
    }