Querystring Format in ASP.NET using C#

Querystring is a way to pass information from one page to another in a web application. It allows developers to send key-value pairs as part of the URL. In ASP.NET using C#, you can easily access and manipulate querystring values.

Accessing Querystring Values

To access querystring values in ASP.NET using C#, you can use the Request.QueryString property. This property allows you to get the querystring values as a collection of key-value pairs.

string value = Request.QueryString["key"];

In the above code, you can replace "key" with the actual querystring key to get its corresponding value.

Constructing a Querystring

To construct a querystring in ASP.NET using C#, you can use the HttpUtility.ParseQueryString method from the System.Web namespace. This method helps in building a querystring by adding key-value pairs.

var queryString = HttpUtility.ParseQueryString(string.Empty);
queryString["key1"] = "value1";
queryString["key2"] = "value2";
string url = "page.aspx?" + queryString.ToString();

In the above code, you can add key-value pairs to the queryString object by assigning values to its keys. Finally, you can append the querystring to the URL by using the ToString method.

URL Encoding

When constructing a querystring, it is essential to encode the values properly to handle special characters. In ASP.NET using C#, you can use the HttpUtility.UrlEncode method to perform URL encoding.

string encodedValue = HttpUtility.UrlEncode(value);

In the above code, the value variable contains the value that you want to encode.

URL Decoding

To decode a querystring value in ASP.NET using C#, you can use the HttpUtility.UrlDecode method. It helps in converting encoded values back to their original form.

string decodedValue = HttpUtility.UrlDecode(encodedValue);

Replace the encodedValue variable with the actual encoded value that you want to decode.

Working with Multiple Querystring Values

If you have multiple values for the same querystring key, you can access them as an array using the Request.QueryString.GetValues method.

string[] values = Request.QueryString.GetValues("key");

In the above code, you can replace "key" with the actual querystring key to get an array of all its corresponding values.

Summary

In summary, querystring format is widely used in ASP.NET for passing data between pages. This guide introduced the basics of accessing and constructing querystrings in ASP.NET using C#. It also provided information about URL encoding and decoding for proper handling of special characters.