c# - Cannot apply indexing with [] to an expression of type 'object'

Question

So far this is what I have.

protected void CategoryRepeater_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        Object dataItem = e.Item.DataItem;

        // code to pull catid out of dataItem
    }

Here's an example of what dataItem contains after running in debug:

dataItem = { TextCategory = "Radiation (Release or Contamination)", catid = 4, TextResult = "Refer to emergency plan and report under code 332.54(A)" , IsReportable = True }

I want to pull the catid out of the object. I have tried casting it, but all attempts to cast it have been unsuccessful. My goal is to use this catid for a nested repeater's databind.. something like this:

using (NERAEntities entities = new NERAEntities())
{
    var Questions = (from x in entities.Questions
                   where x.CategoryID == catid
                   select new { QuestionText = x.Text }); 


    QARepeater.DataSource = Questions;
    QARepeater.DataBind();
}

Answer 1

问题是 DataItem 本身并没有真正的类型（它是一个匿名类）。您需要改用它：

dynamic dataItem = e.Item.DataItem ;
int catId = dataItem.catid ;

显然，如果实际对象没有catId属性，这将在运行时失败。

Answer 2

假设您使用的对象的类型称为 DataItem，请尝试以下操作：

    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        DataItem dataItem = (DataItem) e.Item.DataItem;

        // code to pull catid out of dataItem
    }

Answer 3

也许你可以尝试：

protected void CategoryRepeater_ItemDataBound(object sender, 
    RepeaterItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Item || 
        e.Item.ItemType == ListItemType.AlternatingItem)
    {
        DataRowView row = (DataRowView)e.Item.DataItem;
        int? catID = row["catid"] as int;
    }
}