How to Test Your Request.Querystring[] Variables

How do you test your Request.QueryString[] variables?

Below is an extension method that will allow you to write code like this:

int id = request.QueryString.GetValue<int>("id");
DateTime date = request.QueryString.GetValue<DateTime>("date");

It makes use of TypeDescriptor to perform the conversion. Based on your needs, you could add an overload which takes a default value instead of throwing an exception:

public static T GetValue<T>(this NameValueCollection collection, string key)
{
    if(collection == null)
    {
        throw new ArgumentNullException("collection");
    }

    var value = collection[key];

    if(value == null)
    {
        throw new ArgumentOutOfRangeException("key");
    }

    var converter = TypeDescriptor.GetConverter(typeof(T));

    if(!converter.CanConvertFrom(typeof(string)))
    {
        throw new ArgumentException(String.Format("Cannot convert '{0}' to {1}", value, typeof(T)));
    }

    return (T) converter.ConvertFrom(value);
}

How to check that Request.QueryString has a specific value or not in ASP.NET?

You can just check for null:

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

How to set the value of a query string in test method Moq

Query String

You will also need to mock the query string in the HttpRequestBase object. For that you will need to build the object graph

ControllerContext -> HttpContextBase -> HttpRequestBase

As you are already mocking the ControllerContext of your controller instance, you can use the following code to add the mocked query string:

var queryString = new NameValueCollection { { "code", "codeValue" } };
var mockRequest = new Mock<HttpRequestBase>();
mockRequest.Setup(r => r.QueryString).Returns(queryString);
var mockHttpContext = new Mock<HttpContextBase>();
mockHttpContext.Setup(c => c.Request).Returns(mockRequest.Object);
mockControllerContext.Setup(c => c.HttpContext).Returns(mockHttpContext.Object);

Session

For the mocked session, use the same http context configured above to also return a mock session object:

var mockSession = new Mock<HttpSessionStateBase>();
mockHttpContext.Setup(c => c.Session).Returns(mockSession.Object);
//where mockHttpContext has been created in the code for the queryString above and setup to be returned by the controller context

Then you can set the values the way you did using SetupGet, or you can also use Setup as in

mockSession.Setup(s => s["token"]).Returns("fooToken")

If you want to verify that a value was set on the session, you can add something like this to your assert code:

mockSession.VerifySet(s => s["token"] = "tokenValue", Times.Once);

ActionResult types

What I usually do is to cast the result to the desired type using the as operator. It will return null if the conversion is not possible. So the assert may look like this:

ViewResult result = controller.Index() as ViewResult;

// Assert
Assert.IsNotNull(result);
Assert.AreEqual("fooView", result.ViewName);

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Side Note

If you have many similar tests where the code is using the session and/or query string, there will be quite a few mock objects you need to create and configure on every test.

You could add a setup method to your test class (which is run before each test), and move there all the code that builds the object graph with the mocks. This way you have a fresh controller instance on every test method and the arrange part of every test will just need to setup the mocks behaviour and expectations.

For example, if you have this setup code in your test class:

private HomeController _homeController;
private Mock<HttpSessionStateBase> _mockSession;
private Mock<HttpRequestBase> _mockRequest;

[SetUp]
public void Setup()
{
    _mockRequest = new Mock<HttpRequestBase>();
    _mockSession = new Mock<HttpSessionStateBase>();
    var mockHttpContext = new Mock<HttpContextBase>();
    var mockControllerContext = new Mock<ControllerContext>();

    mockHttpContext.Setup(c => c.Request).Returns(_mockRequest.Object);
    mockHttpContext.Setup(c => c.Session).Returns(_mockSession.Object);
    mockControllerContext.Setup(c => c.HttpContext).Returns(mockHttpContext.Object);

    _homeController = new HomeController();
    _homeController.ControllerContext = mockControllerContext.Object;
}

The code on every test will be reduced to something like this:

[Test]
public void Index_WhenNoTokenInSession_ReturnsDummyViewAndSetsToken()
{
    // Arrange
    var queryString = new NameValueCollection { { "code", "dummyCodeValue" } };
    _mockSession.Setup(s => s["token"]).Returns(null);
    _mockRequest.Setup(r => r.QueryString).Returns(queryString);

    // Act
    ViewResult result = _homeController.Index() as ViewResult;

    // Assert
    Assert.IsNotNull(result);
    Assert.AreEqual("dummy", result.ViewName);
    _mockSession.VerifySet(s => s["token"] = "tokenValue", Times.Once);
}

[Test]
public void Index_WhenTokenInSession_ReturnsDefaultView()
{
    // Arrange
    _mockSession.Setup(s => s["token"]).Returns("foo");

    // Act
    ViewResult result = _homeController.Index() as ViewResult;

    // Assert
    Assert.IsNotNull(result);
    Assert.AreEqual(String.Empty, result.ViewName);
}

Where those tests are testing this dummy Index method

public ActionResult Index()
{
    if (Session["token"] == null)
    {
        if (Request.QueryString["code"] != null)
        {

            Session["token"] = "tokenValue";
            return View("dummy");
        }
    }
    return View();
}

How can I get query string values in JavaScript?

Update: Jan-2022

Using Proxy() is faster than using Object.fromEntries() and better supported

const params = new Proxy(new URLSearchParams(window.location.search), {
  get: (searchParams, prop) => searchParams.get(prop),
});
// Get the value of "some_key" in eg "https://example.com/?some_key=some_value"
let value = params.some_key; // "some_value"

Update: June-2021

For a specific case when you need all query params:

const urlSearchParams = new URLSearchParams(window.location.search);
const params = Object.fromEntries(urlSearchParams.entries());

Update: Sep-2018

You can use URLSearchParams which is simple and has decent (but not complete) browser support.

const urlParams = new URLSearchParams(window.location.search);
const myParam = urlParams.get('myParam');

Original

You don't need jQuery for that purpose. You can use just some pure JavaScript:

function getParameterByName(name, url = window.location.href) {
    name = name.replace(/[\[\]]/g, '\\$&');
    var regex = new RegExp('[?&]' + name + '(=([^&#]*)|&|#|$)'),
        results = regex.exec(url);
    if (!results) return null;
    if (!results[2]) return '';
    return decodeURIComponent(results[2].replace(/\+/g, ' '));
}

Usage:

// query string: ?foo=lorem&bar=&baz
var foo = getParameterByName('foo'); // "lorem"
var bar = getParameterByName('bar'); // "" (present with empty value)
var baz = getParameterByName('baz'); // "" (present with no value)
var qux = getParameterByName('qux'); // null (absent)

NOTE: If a parameter is present several times (?foo=lorem&foo=ipsum), you will get the first value (lorem). There is no standard about this and usages vary, see for example this question: Authoritative position of duplicate HTTP GET query keys.

NOTE: The function is case-sensitive. If you prefer case-insensitive parameter name, add 'i' modifier to RegExp

NOTE: If you're getting a no-useless-escape eslint error, you can replace name = name.replace(/[\[\]]/g, '\\$&'); with name = name.replace(/[[\]]/g, '\\$&').

---

This is an update based on the new URLSearchParams specs to achieve the same result more succinctly. See answer titled "URLSearchParams" below.

How to get GET (query string) variables in Express.js on Node.js?

In Express it's already done for you and you can simply use req.query for that:

var id = req.query.id; // $_GET["id"]

Otherwise, in NodeJS, you can access req.url and the builtin url module to url.parse it manually:

var url = require('url');
var url_parts = url.parse(request.url, true);
var query = url_parts.query;

Most elegant way of checking the value of a query string parameter if not null?

I thought first of offering

if ((Page.Request.QueryString["ParamName"] ?? "") == expectedResult) {

but quickly realized that with strings, comparing some string with null is fine, and will produce false, so really just using this will work:

if(Page.Request.QueryString["ParamName"] == expectedResult)
    //Do something spectacular

how does Request.QueryString work?

The HttpRequest class represents the request made to the server and has various properties associated with it, such as QueryString.

The ASP.NET run-time parses a request to the server and populates this information for you.

Read HttpRequest Properties for a list of all the potential properties that get populated on you behalf by ASP.NET.

Note: not all properties will be populated, for instance if your request has no query string, then the QueryString will be null/empty. So you should check to see if what you expect to be in the query string is actually there before using it like this:

if (!String.IsNullOrEmpty(Request.QueryString["pID"]))
{
    // Query string value is there so now use it
    int thePID = Convert.ToInt32(Request.QueryString["pID"]);
}

Get full query string in C# ASP.NET

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

In Go's http package, how do I get the query string on a POST request?

A QueryString is, by definition, in the URL. You can access the URL of the request using req.URL (doc). The URL object has a Query() method (doc) that returns a Values type, which is simply a map[string][]string of the QueryString parameters.

If what you're looking for is the POST data as submitted by an HTML form, then this is (usually) a key-value pair in the request body. You're correct in your answer that you can call ParseForm() and then use req.Form field to get the map of key-value pairs, but you can also call FormValue(key) to get the value of a specific key. This calls ParseForm() if required, and gets values regardless of how they were sent (i.e. in query string or in the request body).

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