为什么页面回发时会触发GridView.RowCreated事件

Question

All, I was using the RowCreated event to fill content for the every Row of the GridView . But I found the RowCreated event of GridView is triggered whenever I click any server control like Asp.net Button which could trigger the page postback. And it will cause a problem which the e.Row.DataItem is not available(null).

The code simply looks like below.

    protected void GridView1_RowCreated(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            SomeObject mapItem = (SomeObject)e.Row.DataItem;//DataItem is null when postback.
        }         
    }

And I am sure I didn't bind anything DataTable or List<T> with the GridView when postback. After researched. I also found if I move the code to RowDataBound event. everything is ok. the problem is gone. I just don't know why. Hope someone can help me. thanks.

Answer 1

As per MSDN ,

Before the GridView control can be rendered, a GridViewRow object must be created for each row in the control. The RowCreated event is raised when each row in the GridView control is created. This enables you to provide an event-handling method that performs a custom routine, such as adding custom content to a row, whenever this event occurs.

Also check below link that explains why it happens:

GridView event raise unexpectedly after postback

Answer 2

RowCreated is focused on parsing Gridview row's definition and creating the Gridview row's control structure,

RowDataBound is focused on bind data to the row's controls created in the RowCreated.

Also RowCreated is invoked automatically in both init and postback case, but RowDataBound is only invoke when the DataBind is called.

Every time your grid has bind data, the RowCreated event will call each time.

Have you bind gridview on page load? If this is your case, the RowCreated event will fire in every postback. To avoid this, check !IsPostback to control it and manage your gridview binding. In in most cases, everyone (including Microsoft) raccomend to use RowDataBound event instead of RowCreated.

Hope to be helpful :)