Solution to Request. QueryString exceptions

In web requests, we often need to use the page to pass values, but sometimes exceptions occur if you do not pay attention to them.

For example, the address of a page is ../index. aspx.

Its background file contains the statement for processing the passed value: if (Request. queryString ["TypeID"] = null | Request. queryString ["TypeID"]. toString () = "")

When your address.../index. aspx? If TypeID = 1, the system runs normally without any exception.

However, when your address is:

.. /Index. when aspx is used, the if (Request. queryString ["TypeID"]. toString () = "" | Request. queryString ["TypeID"]. toString () = null)

The exception occurs. What is this?

The main reason is the Request. queryString ["TypeID"] is an object that is the same as null, When you Request. queryString ["TypeID"]. toString () = "", because the Request. queryString ["TypeID"] This object does not exist at all and will not be converted to "". Therefore, when you are not sure whether there is a page value transfer, we 'd better judge whether the passed object does not exist and then process it as a string so that no exception will occur.