How to Parse a Query String without using the HttpUtility Class in System.Web

I wanted to remove the dependency on System.Web so that I could parse the query string of a ClickOnce deployment, while having the prerequisites limited to the "Client-only Framework Subset".

Here is a simple method that will accomplish this task.  I have also included some unit tests.  And, last but not least, I posted this on StackOverflow.  Thanks to rp for writing the initial method.

Code

1. public static NameValueCollection ParseQueryString(string s)
2.         {
3.             NameValueCollection nvc = new NameValueCollection();
5.             // remove anything other than query string from url
6.             if(s.Contains("?"))
7.             {
8.                 s = s.Substring(s.IndexOf('?') + 1);
9.             }
11.             foreach (string vp in Regex.Split(s, "&"))
12.             {
13.                 string[] singlePair = Regex.Split(vp, "=");
14.                 if (singlePair.Length == 2)
15.                 {
16.                     nvc.Add(singlePair[0], singlePair[1]);
17.                 }
18.                 else
19.                 {
20.                     // only one key with no value specified in query string
21.                     nvc.Add(singlePair[0], string.Empty);
22.                 }
23.             }
25.             return nvc;
26.         \

Unit Tests

1. [TestMethod]
2.         public void ParseQueryString_OneNameValueParameter()
3.         {
4.             //
5.             // TODO: Add test logic    here
6.             //
8.             const string queryString = "http://www.foo.com/testpage.htm?mykey=myvalue";
10.             var result = Helper.ParseQueryString(queryString);
11.             
12.             Assert.AreEqual(1, result.Count);
13.             Assert.AreEqual("myvalue", result["mykey"]);
14.         }
16.         [TestMethod]
17.         public void ParseQueryString_ThreeNameValueParameter()
18.         {
19.             const string queryString = "http://www.foo.com/?mykey1=myval1&mykey2=myval2&mykey3=myval3";
21.             var result = Helper.ParseQueryString(queryString);
23.             Assert.AreEqual(3, result.Count);
25.             Assert.AreEqual("myval1",result["mykey1"]);
26.             Assert.AreEqual("myval2", result["mykey2"]);
27.             Assert.AreEqual("myval3", result["mykey3"]);
29.         }
31.         [TestMethod]
32.         public void ParseQueryString_OneKeyWithNoValue()
33.         {
34.             const string queryString = "http://www.foo.com/?mykey1";
36.             var result = Helper.ParseQueryString(queryString);
38.             Assert.AreEqual(1,result.Count);
39.             Assert.AreEqual(string.Empty, result["mykey1"]);
40.         }
42.         [TestMethod]
43.         public void ParseQueryString_MultipleKeysWithNoValue()
44.         {
45.             const string queryString = "http://www.foo.com/?mykey1=myval1&mykey2&mykey3=myval3";
47.             var result = Helper.ParseQueryString(queryString);
49.             Assert.AreEqual(3, result.Count);
51.             Assert.AreEqual("myval1", result["mykey1"]);
52.             Assert.AreEqual(string.Empty, result["mykey2"]);
53.             Assert.AreEqual("myval3", result["mykey3"]);
55.         }
57.         [TestMethod]
58.         public void ParseQueryString_NoUrlSpecifiedWithQueryString()
59.         {
60.             const string queryString = "mykey1=myval1&mykey2=myval2";
62.             var result = Helper.ParseQueryString(queryString);
64.             Assert.AreEqual(2, result.Count);
65.             
66.             Assert.AreEqual("myval1", result["mykey1"]);
67.             Assert.AreEqual("myval2", result["mykey2"]);
69.         \