Why is DataItem always null in the Page_Load handler?

Question

I've created an ASP.net web page with an ASP Repeater. I bind the ASP Repeater with an IOrderedEnumerable<int> DataSource.

I need to access the Repeater DataItems at inside the Page_Load event handler. However, when I try to get the value of repeater.Items[x].DataItem, I always get null. There should always be an integer value here.

In spite of this, the page otherwise renders fine. Why can't I access the DataItem property of my RepeaterItems inside the Page_Load event handler?

Why don't you just access your collection directly? There would be no reason to only be able to access the item through the DataItem property. — oscilatingcretin, Aug 23 '11 at 19:13

score 2 · Answer 1 · answered Aug 23 '11 at 18:17

2

Your Repeater doesn't databind until later in the page lifecycle. If you want to reference Repeater.Items[i].DataItem in a Page.Load handler, try to early-bind the Repeater first:

repeater.DataBind()

answered Aug 23 '11 at 18:17

pseudocoder

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I tried this in testing and had trouble with implementing `IOrderedEnumerable` as a datasource. I am not very familiar with LINQ, and I think your problem might center around the use of that type of data source. I retagged the question with LINQ so hopefully that will get some more answerers on this question. – pseudocoder Aug 23 '11 at 19:08

score 0 · Answer 2 · answered Aug 23 '11 at 18:18

0

Its only available during databinding.

answered Aug 23 '11 at 18:18

JNappi

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I've tried to access it at all different points of the page lifecycle. It seems awfully arbitrary to only be able to access it at DataBinding... – Vivian River Aug 23 '11 at 18:22

score 0 · Answer 3 · answered Aug 23 '11 at 18:22

As everyone else has said, it's only available during databinding. You will need to wire up the OnItemDataBound event of the repeater. In its event handler, you can do this:

protected void Repeater_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
    switch (e.Item.ItemType)
    {
        case ListItemType.Item:
        case ListItemType.AlternatingItem:
            WhateverType Item = e.Item.DataItem as WhateverType;
            break;
    }
}

score 0 · Answer 4 · answered Aug 23 '11 at 18:24

The data items only exist after the databinding process has taken place. The only thing that is preserved across postbacks in the repeater are the control properties that are serialized in viewstate. If you need the data in those items, you can do like pseudocoder said and databind earlier or if that is not possible you could write a utility function that takes a repeater data item and extracts it from the controls in your repeater (assuming you stored all the information you need in those controls somehow)

Why is DataItem always null in the Page_Load handler?

4 Answers4