is there a sort of isset() on .NET/C#?

Question

I need to check if there is a param on the uri request.

So I need to check if that param is set. Is there a function on .NET/C#?

Answer 1

An unset value will be null or empty:

value = Request["param"];
if (String.IsNullOrEmpty(value))
{
    // param is not set
}

If the param name is in the query string but the value is not, it will be empty. If the name is not in the query string, the value will be null. For example.

&param1=&param2=value 
// Request["param1"] is String.Empty
// Request["param3"] is null

Answer 2

Yes, you can use HttpUtility.ParseQueryString() utility method which returns NameValueCollection and then cust call Get():

bool contains = HttpUtility.ParseQueryString(uri.Query)
                           .Get("ParameterName") != null;

Get() method

Returns A String that contains a comma-separated list of the values associated with the specified key from the NameValueCollection, if found; otherwise, null

EDIT:

If you have an instance of the HttpRequest then just use built in indexer like below:

bool contains = Request["ParamName"] != null;