试图让我陷入条件NULL语法

Question

I've got a ASP.NET search page that displays a SQL bound ListView after a Search button is clicked. In the EmptyDataTemplate, I've got an asp label based on the ID they searched for in a message. "No results found for " kinda thing.

Here's my original codebehind for the button click:

protected void btnSearch_Command(object sender, CommandEventArgs e)
{

    Label lbl = (Label)lvMatOrders.Controls[0].Controls[0].FindControl("lblProjectID");
    if (lbl != null)  // this means EmptyDataTemplate is used, else ItemTemplate
    {

        if (string.IsNullOrEmpty(txtProjectID.Text))
        {
            lbl.Text = "#####";
        }
        else
        {
            lbl.Text = txtProjectID.Text;
        }

    }
}

Am I correct in understanding that I can reduce it down to the following?

Label lbl = (Label)lvMatOrders.Controls[0].Controls[0].FindControl("lblProjectID");
lbl?.Text = (string.IsNullOrEmpty(txtProjectID.Text)) ? "#####" : txtProjectID.Text;

The main goal here is to make sure that the code that attempts to assign either the "#####" or txtProjectID.Text to lbl.Text doesn't get executed if the page already has results from a previous search displayed as the page isn't showing the EmptyDataTemplate and thus no lblProjectID to assign the text to.

Will the lbl?.Text line be attempted if the page is in ItemTemplate mode?

Answer 1

No, the code will not even compile, you will get the error "The left-hand side of an assignment must be a variable, property or indexer"

You can not use the .? operator on the left hand side of a equals sign, only the right hand side.