QueryString Link Help

How come when I put this code in my page to request the query string my page is returning a href of nothing?

Code In Page:

<a href='<% String.Format("book.aspx?id=" + Request.QueryString["id"]); %>'>Test</a>

Result:

<a href=''>Test</a>
开发者_运维技巧

---

You need to use <%= and not <% to output the result of the String.Format to the page. Right now you are just discarding the result.

---

I'm not sure why you have the String.Format in there, all you need is this:

<a href="book.aspx?id=<%=Request.QueryString["id"] %>">Test</a>

Also, even though ASP.NET checks for potentially dangerous request values, it's good practice to either encode or validate values like this:

<a href="book.aspx?id=<%=Server.HtmlEncode(Request.QueryString["id"]) %>">Test</a>

or

<a href="book.aspx?id=<%=Convert.ToInt32(Request.QueryString["id"]) %>">Test</a>