Get full query string in C# ASP.NET

As a PHP programmer I’m used to using $_GET to retrieve the HTTP query string… and if I need the whole string, theres loads of ways to do it.

In ASP however, I can’t seem to get the query.

Here is the code for news.aspx (embedded in some HTML):

<%                             
    string URL = "http://www.example.com/rendernews.php?"+Request.Querystring;
    System.Net.WebClient wc = new System.Net.WebClient();
    string data = wc.DownloadString(URL);
    Response.Output.Write(data);
%>

I am fetching a PHP script’s output from a remote server, and this works perfectly without the Request.Querystring.

The issue is that I’m trying to get the full query string on the first line: Request.Querystring. I am getting an error “Object reference not set to an instance of an object” which basically means that Request.Querystring doesn’t exist.

Any idea what the problem is here? How can I get that query string so when index.aspx is called like http://test.com/news.aspx?id=2 my script fetches http://www.example.com/rendernews.php?id=2

Answers:

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Method 1

Try Request.Url.Query if you want the raw querystring as a string.

Method 2

This should work fine for you.

Write this code in the Page_Load event of the page.

string ID = Request.QueryString["id"].ToString();
Response.Redirect("http://www.example.com/rendernews.php?id=" + ID);

Method 3

Request.QueryString returns you a collection of Key/Value pairs representing the Query String. Not a String. Don’t think that would cause a Object Reference error though. The reason your getting that is because as Mauro pointed out in the comments. It’s QueryString and not Querystring.

Try:

Request.QueryString.ToString();

or

<%                                 
    string URL = Request.Url.AbsoluteUri 
    System.Net.WebClient wc = new System.Net.WebClient();
    string data = wc.DownloadString(URL);
    Response.Output.Write(data);
%>

Same as your code but Request.Url.AbsoluteUri will return the full path, including the query string.

Method 4

Just use Request.QueryString.ToString() to get full query string, like this:

string URL = "http://www.example.com/rendernews.php?"+Request.Querystring.ToString();

Method 5

I have tested your example, and while Request.QueryString is not convertible to a string neither implicit nor explicit still the .ToString() method returns the correct result.

Further more when concatenating with a string using the “+” operator as in your example it will also return the correct result (because this behaves as if .ToString() was called).

As such there is nothing wrong with your code, and I would suggest that your issue was because of a typo in your code writing “Querystring” instead of “QueryString”.

And this makes more sense with your error message since if the problem is that QueryString is a collection and not a string it would have to give another error message.

Method 6

just a moment ago, i came across with the same issue. and i resolve it in the following manner.

Response.Redirect("../index.aspx?Name="+this.textName.Text+"&LastName="+this.textlName.Text);

with reference to the this

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