Get full query string in C# ASP.NET

Question

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

Does it always fail, or is there edge cases like no get variables defined? — Matt, Dec 10 '09 at 09:38

score 206 · Accepted Answer · edited Oct 25 '15 at 12:37

206

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

edited Oct 25 '15 at 12:37

H. Pauwelyn

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answered Dec 10 '09 at 09:33

nitzmahone

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score 19 · Answer 2 · edited Aug 14 '12 at 10:17

19

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);

edited Aug 14 '12 at 10:17

Govind Malviya

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answered Dec 10 '09 at 09:41

Naveed Butt

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score 11 · Answer 3 · edited Oct 25 '15 at 12:37

11

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.

edited Oct 25 '15 at 12:37

H. Pauwelyn

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answered Dec 10 '09 at 09:27

Damien

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With that I get: "'System.Web.HttpRequest' does not contain a definition for 'Querystring' and no extension method 'Querystring' accepting a first argument of type 'System.Web.HttpRequest'" and when I try adding System.Web before it, I get "The type or namespace name 'Request' does not exist in the namespace 'System.Web' (are you missing an assembly?) " – Antony Carthy Dec 10 '09 at 09:39
Might want to make sure you aren't overriding Request somewhere. I have something using Request.Querystring[.ToString()] in production and it works flawlessly. – Matt Dec 10 '09 at 09:50
2

isnt it QueryString and not Querystring? code above looks like c# - remember case sensitivity – Mauro Dec 10 '09 at 10:00
1

In my case, this is exactly what I want to avoid, because ToString() is buggy in the **** old version of the .NET framework that I'm forced to use. – Florian Winter Aug 14 '18 at 11:50

score 1 · Answer 4 · answered Dec 10 '09 at 09:47

1

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

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

answered Dec 10 '09 at 09:47

terR0Q

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This returns the name of the class. – Allov Jul 28 '11 at 14:37
1

@Allov I have tested that, and it did returned the query string correctly, and in fact even without .ToString() it will work when concatenating with a string – yoel halb Dec 14 '12 at 02:13
It didn't work in .Net 4. Possibly it up votes are for other versions of .Net. – Fabio Milheiro Jan 29 '15 at 11:54
1

It is actually changing & for & so it renders it unusable. Request.Url.Query is much better. – Jiří Herník May 02 '18 at 08:35

score 0 · Answer 5 · answered Dec 14 '12 at 02:19

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.

score -1 · Answer 6 · answered Mar 19 '13 at 14:21

-1

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

answered Mar 19 '13 at 14:21

user2147280

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Never never never build URLs like this in any framework or programming language. Use URL builders. They take care of encoding for you, which the code above doesn't do. – Florian Winter Aug 14 '18 at 11:51

Get full query string in C# ASP.NET

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