How To Get All QueryString Keys In ASP.NET

Introduction

Sometimes we pass values from one page to other page in URL. QueryString is main object which helps to do the same.

Using code

QueryString - As per W3(WWW), a query string is the part of a uniform resource locator (URL)

containing data. The QueryString collection is used to retrieve the variable values in the HTTP query string. It is also considered as Client-Side state management technique in ASP.NET. As a security, always encode header data or user input before using it. A method for encoding data is Server.HTMLEncode() and for decode use Server.HTMLDecode().

The QueryString is specified by the values following the question mark (?), like this:

http://localhost:1997/WebForm1.aspx?id=10&name=manas

How to get all Keys and Values

Option 1: Using AllKeys properties

foreach (var cookieKey in Request.QueryString.AllKeys)
{
Response.Write("Key: " + cookieKey + ", Value:" + Request.QueryString[cookieKey]);
}

Option 2: Using no of QueryString Count

for (int idx = 0; idx < Request.QueryString.Count; idx++)
{
Response.Write("Value:" + Request.QueryString[idx]);
}

Option 3: Using Keys Count

for (int idx = 0; idx < Request.QueryString.Keys.Count; idx++)
{
Response.Write("Key: " + Request.QueryString.Keys[idx] +
", Value:" + Request.QueryString[Request.QueryString.Keys[idx]]);
}

If you want to get querystring value as string:

string temp = Request.QueryString.ToString(); // id=10&name=manas

How to check a key is present:

Sometimes we check whether a key is present in QueryString. Below are two ways to check key is available in QueryString:

Option 1: Using AllKeys properties

Request.QueryString.AllKeys.Contains("name"); // Return true
Request.QueryString.AllKeys.Contains("name1"); // Return false
Request.QueryString.AllKeys.Contains("Name"); // Return false due to Case-sensitive

Option 2 : Using NULL checking

if(Request.QueryString["name"] != null)
{
//your code that depends on requirement
}

We have HasKeys properties of QueryString which provides whether any keys is present. If there is no QueryString value then it returns false.

// http://localhost:1997/WebForm1.aspx?id=10&name=manas
Request.QueryString.HasKeys(); // true
// http://localhost:1997/WebForm1.aspx
Request.QueryString.HasKeys(); // false

Conclusion

We discussed how to get all cookies are available in a page.

Hope this helps.