ASP.NET gridview binding doesn't work / control doesn't show up

Question

another beginner problem. Why isn't the following code with an asp.net page not working?

protected void Page_Load(object sender, EventArgs e)
{
    List<string> list = new List<string>();
    list.Add("Teststring");
    this.GridView.DataSource = list;
}

GridView is the GridView control on that asp page. However, no grid shows up at all. It's both enabled and visible. Plus when I debug, the GridView.Rows.Count is 0. I always assumed you can just add generic Lists and all classes implementing IList as a DataSource, and the gridview will then display the content automatically? Or is the reason here that it's been done in the page_load event handler. and if, how can I fill a grid without any user interaction at startup?

Thanks again.

Zachary · Accepted Answer · 2009-06-09 19:24:25Z

4

You should call DataBind().

answered Jun 9, 2009 at 19:24

Zachary

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Comments

TheTXI · Accepted Answer · 2009-06-09 19:27:40Z

3

You forgot to call the GridView's .DataBind() method. This is what will link the control to its data source and load the results.

Example:

protected void Page_Load(object sender, EventArgs e)
{
    List<string> list = new List<string>();
    list.Add("Teststring");
    this.GridView.DataSource = list;
    this.GridView.DataBind();
}

answered Jun 9, 2009 at 19:27

TheTXI

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Comments

Rob Allen · Accepted Answer · 2009-06-09 19:34:01Z

2

Unlike in winforms, for ASP developement you need to specifically call GridView.DataBind();. I would also break out that code into a separate method and wrap the initial call into a check for postback. That will save you some headaches down the road.

protected void Page_Load(object sender, EventArgs e)
{
   if (!Page.IsPostback)
   {
       List<string> list = new List<string>();
       list.Add("Teststring");
       bindMydatagrid(list);
   }
}

protected void bindMydatagrid(List<string> list)
{
    gv.DataSource = list;
    gv.DataBind();
}

answered Jun 9, 2009 at 19:34

Rob Allen

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3 Comments

noisecoder Over a year ago

Thank you all guys, I'm really stupid. Works like a charm now! Btw, what would be the danger if don't check for IsPostback? I think I still haven't got a grip on that one.

Rob Allen Over a year ago

@noisecoder - Without the IsPostback check the grid will rebind every time your page refreshes (button clicks, selected index changes... etc).

Rob Allen Over a year ago

Also - the separate method is for easy manually rebinds when the data changes

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