以编程方式在Asp.Net ListView中选择项目

快速搜索后,我找不到这个看似简单的事情的答案.

如何在Asp.Net ListView中手动选择项？

我有一个SelectedItemTemplate,但我不想使用asp:button或asp:LinkBut​​ton来选择一个项目.我希望它可以通过URL完成.例如,像QueryString一样.

我想象的方式是在ItemDataBound上,检查条件,然后将其设置为selected,如果为true,但我该怎么做？

例如:

protected void lv_ItemDataBound(object sender, ListViewItemEventArgs e) {

  using (ListViewDataItem dataItem = (ListViewDataItem)e.Item) {

     if (dataItem != null) {
        if( /* item select condition */ ) {   

            // What do I do here to Set this Item to be Selected?
            // edit: Here's the solution I'm using :
            ((ListView)sender).SelectedIndex = dataItem.DisplayIndex;

            // Note, I get here and it gets set
            // but the SelectedItemTemplate isn't applied!!!

        }
     }
  }
}

我确定这是一行或两行代码.

编辑:我已经更新了代码以反映解决方案,似乎我可以选择ListView的SelectedItemIndex,但是,它实际上并没有呈现SelectedItemTemplate.我不知道我是否应该在ItemDataBound事件中执行此操作,如下所示.

我看了一下ListView中的一些内容,并认为这可能是最好的方法.

void listView_ItemCreated(object sender, ListViewItemEventArgs e)
{
    // exit if we have already selected an item; This is mainly helpful for
    // postbacks, and will also serve to stop processing once we've found our
    // key; Optionally we could remove the ItemCreated event from the ListView 
    // here instead of just returning.
    if ( listView.SelectedIndex > -1 ) return; 

    ListViewDataItem item = e.Item as ListViewDataItem;
    // check to see if the item is the one we want to select (arbitrary) just return true if you want it selected
    if (DoSelectDataItem(item)==true)
    {
        // setting the SelectedIndex is all we really need to do unless 
        // we want to change the template the item will use to render;
        listView.SelectedIndex = item.DisplayIndex;
        if ( listView.SelectedItemTemplate != null )
        {
            // Unfortunately ListView has already a selected a template to use;
            // so clear that out
            e.Item.Controls.Clear();
            // intantiate the SelectedItemTemplate in our item;
            // ListView will DataBind it for us later after ItemCreated has finished!
            listView.SelectedItemTemplate.InstantiateIn(e.Item);
        }
    }
}

bool DoSelectDataItem(ListViewDataItem item)
{
    return item.DisplayIndex == 0; // selects the first item in the list (this is just an example after all; keeping it simple :D )
}

笔记

ListView选择一个项目在DataBinding事件触发后将使用的模板.因此,如果在此之前设置了SelectedIndex,则无需再进行任何操作

在DataBinding工作之后的任何地方设置SelectedIndex,你只是没有得到SelectedItemTemplate.为此你要么重新绑定数据; 或者在ListViewItem上重新实例化SelectedItemTemplate.一定要先清除ListViewItem.Controls集合!

更新我删除了大部分原始解决方案,因为这应该更好,更多情况下.

您可以设置ListViews SelectedIndex

list.SelectedIndex = dataItem.DisplayIndex; // don't know which index you need
list.SelectedIndex = dataItem.DataItemIndex; 

更新

如果在页面加载时加载数据,则可能必须遍历数据以查找索引,然后在调用DataBind()方法之前设置SelectedIndex值.

public void Page_Load(object sender, EventArgs e)
{
  var myData = MyDataSource.GetPeople();
  list.DataSource = myData;
  list.SelectedIndex = myData.FirstIndexOf(p => p.Name.Equals("Bob", StringComparison.InvariantCultureIgnoreCase));
  list.DataBind();
}


public static class EnumerableExtensions
{
    public static int FirstIndexOf(this IEnumerable source, Predicate predicate)
    {
        int count = 0;
        foreach(var item in source)
        {
            if (predicate(item))
                return count;
            count++;
        }
        return -1;
    }
}