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I've seen a couple examples of how to check if a query string exists in a url with C#:
www.site.com/index?query=yes
if(Request.QueryString["query"]=="yes")
But how would I check a string without a parameter? I just need to see if it exists.
www.site.com/index?query
if(Request.QueryString["query"] != null) //why is this always null?
I know there's probably a simple answer and I'll feel dumb, but I haven't been able to find it yet. Thanks!
875
To check if a url has query parameters, call the indexOf() method on the url, passing it a question mark, and check if the result is not equal to -1 , e.g. url. indexOf('? ') !== -1 .
Check if a query string parameter existsThe URLSearchParams.has() method returns true if a parameter with a specified name exists.
A Query String collection is a parsed version of the QUERY_STRING variable in the Server Variables collection. It enable us to retrieve the QUERY_STRING variable by name. When we use parameters with Request. QueryString, the server parses the parameters sent to the request and returns the effective or specified data.
If you do not specify a value, the key will be automatically set to null, so you cannot check its existence.
In order to check if the value actually exists, you can check in the collection of Values equalling null if it contains your Key:
Request.QueryString.GetValues(null).Contains("query")
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