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Easier way to extract ID from a string? [duplicate]

I would like to parse a string such as p1=6&p2=7&p3=8 into a NameValueCollection.
What is the most elegant way of doing this when you don't have access to the Page.Request object?

There's a built-in .NET utility for this: HttpUtility.ParseQueryString
// C#
NameValueCollection qscoll = HttpUtility.ParseQueryString(querystring);
' VB.NET
Dim qscoll As NameValueCollection = HttpUtility.ParseQueryString(querystring)
You may need to replace querystring with new Uri(fullUrl).Query.

HttpUtility.ParseQueryString will work as long as you are in a web app or don't mind including a dependency on System.Web. Another way to do this is:
NameValueCollection queryParameters = new NameValueCollection();
string[] querySegments = queryString.Split('&');
foreach(string segment in querySegments)
{
string[] parts = segment.Split('=');
if (parts.Length > 0)
{
string key = parts[0].Trim(new char[] { '?', ' ' });
string val = parts[1].Trim();
queryParameters.Add(key, val);
}
}

A lot of the answers are providing custom examples because of the accepted answer's dependency on System.Web. From the Microsoft.AspNet.WebApi.Client NuGet package there is a UriExtensions.ParseQueryString, method that can also be used:
var uri = new Uri("https://stackoverflow.com/a/22167748?p1=6&p2=7&p3=8");
NameValueCollection query = uri.ParseQueryString();
So if you want to avoid the System.Web dependency and don't want to roll your own, this is a good option.

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".
I liked rp's answer. I added some additional logic.
public static NameValueCollection ParseQueryString(string s)
{
NameValueCollection nvc = new NameValueCollection();
// remove anything other than query string from url
if(s.Contains("?"))
{
s = s.Substring(s.IndexOf('?') + 1);
}
foreach (string vp in Regex.Split(s, "&"))
{
string[] singlePair = Regex.Split(vp, "=");
if (singlePair.Length == 2)
{
nvc.Add(singlePair[0], singlePair[1]);
}
else
{
// only one key with no value specified in query string
nvc.Add(singlePair[0], string.Empty);
}
}
return nvc;
}

To do this without System.Web, without writing it yourself, and without additional NuGet packages:
Add a reference to System.Net.Http.Formatting
Add using System.Net.Http;
Use this code:
new Uri(uri).ParseQueryString()
https://msdn.microsoft.com/en-us/library/system.net.http.uriextensions(v=vs.118).aspx

I needed a function that is a little more versatile than what was provided already when working with OLSC queries.
Values may contain multiple equal signs
Decode encoded characters in both name and value
Capable of running on Client Framework
Capable of running on Mobile Framework.
Here is my solution:
Public Shared Function ParseQueryString(ByVal uri As Uri) As System.Collections.Specialized.NameValueCollection
Dim result = New System.Collections.Specialized.NameValueCollection(4)
Dim query = uri.Query
If Not String.IsNullOrEmpty(query) Then
Dim pairs = query.Substring(1).Split("&"c)
For Each pair In pairs
Dim parts = pair.Split({"="c}, 2)
Dim name = System.Uri.UnescapeDataString(parts(0))
Dim value = If(parts.Length = 1, String.Empty,
System.Uri.UnescapeDataString(parts(1)))
result.Add(name, value)
Next
End If
Return result
End Function
It may not be a bad idea to tack <Extension()> on that too to add the capability to Uri itself.

If you don't want the System.Web dependency, just paste this source code from HttpUtility class.
I just whipped this together from the source code of Mono. It contains the HttpUtility and all it's dependencies (like IHtmlString, Helpers, HttpEncoder, HttpQSCollection).
Then use HttpUtility.ParseQueryString.
https://gist.github.com/bjorn-ali-goransson/b04a7c44808bb2de8cca3fc9a3762f9c

If you want to avoid the dependency on System.Web that is required to use HttpUtility.ParseQueryString, you could use the Uri extension method ParseQueryString found in System.Net.Http.
Make sure to add a reference (if you haven't already) to System.Net.Http in your project.
Note that you have to convert the response body to a valid Uri so that ParseQueryString (in System.Net.Http)works.
string body = "value1=randomvalue1&value2=randomValue2";
// "http://localhost/query?" is added to the string "body" in order to create a valid Uri.
string urlBody = "http://localhost/query?" + body;
NameValueCollection coll = new Uri(urlBody).ParseQueryString();

I just realized that Web API Client has a ParseQueryString extension method that works on a Uri and returns a HttpValueCollection:
var parameters = uri.ParseQueryString();
string foo = parameters["foo"];

private void button1_Click( object sender, EventArgs e )
{
string s = #"p1=6&p2=7&p3=8";
NameValueCollection nvc = new NameValueCollection();
foreach ( string vp in Regex.Split( s, "&" ) )
{
string[] singlePair = Regex.Split( vp, "=" );
if ( singlePair.Length == 2 )
{
nvc.Add( singlePair[ 0 ], singlePair[ 1 ] );
}
}
}

Just access Request.QueryString. AllKeys mentioned as another answer just gets you an array of keys.

HttpUtility.ParseQueryString(Request.Url.Query) return is HttpValueCollection (internal class). It inherits from NameValueCollection.
var qs = HttpUtility.ParseQueryString(Request.Url.Query);
qs.Remove("foo");
string url = "~/Default.aspx";
if (qs.Count > 0)
url = url + "?" + qs.ToString();
Response.Redirect(url);

Since everyone seems to be pasting his solution.. here's mine :-)
I needed this from within a class library without System.Web to fetch id parameters from stored hyperlinks.
Thought I'd share because I find this solution faster and better looking.
public static class Statics
public static Dictionary<string, string> QueryParse(string url)
{
Dictionary<string, string> qDict = new Dictionary<string, string>();
foreach (string qPair in url.Substring(url.IndexOf('?') + 1).Split('&'))
{
string[] qVal = qPair.Split('=');
qDict.Add(qVal[0], Uri.UnescapeDataString(qVal[1]));
}
return qDict;
}
public static string QueryGet(string url, string param)
{
var qDict = QueryParse(url);
return qDict[param];
}
}
Usage:
Statics.QueryGet(url, "id")

Hit up Request.QueryString.Keys for a NameValueCollection of all query string parameters.

To get all Querystring values try this:
Dim qscoll As NameValueCollection = HttpUtility.ParseQueryString(querystring)
Dim sb As New StringBuilder("<br />")
For Each s As String In qscoll.AllKeys
Response.Write(s & " - " & qscoll(s) & "<br />")
Next s

var q = Request.QueryString;
NameValueCollection qscoll = HttpUtility.ParseQueryString(q.ToString());

I translate to C# version of josh-brown in VB
private System.Collections.Specialized.NameValueCollection ParseQueryString(Uri uri)
{
var result = new System.Collections.Specialized.NameValueCollection(4);
var query = uri.Query;
if (!String.IsNullOrEmpty(query))
{
var pairs = query.Substring(1).Split("&".ToCharArray());
foreach (var pair in pairs)
{
var parts = pair.Split("=".ToCharArray(), 2);
var name = System.Uri.UnescapeDataString(parts[0]);
var value = (parts.Length == 1) ? String.Empty : System.Uri.UnescapeDataString(parts[1]);
result.Add(name, value);
}
}
return result;
}

let search = window.location.search;
console.log(search);
let qString = search.substring(1);
while(qString.indexOf("+") !== -1)
qString = qString.replace("+", "");
let qArray = qString.split("&");
let values = [];
for(let i = 0; i < qArray.length; i++){
let pos = qArray[i].search("=");
let keyVal = qArray[i].substring(0, pos);
let dataVal = qArray[i].substring(pos + 1);
dataVal = decodeURIComponent(dataVal);
values[keyVal] = dataVal;
}

This is my code, I think it's very useful:
public String GetQueryString(string ItemToRemoveOrInsert = null, string InsertValue = null )
{
System.Collections.Specialized.NameValueCollection filtered = new System.Collections.Specialized.NameValueCollection(Request.QueryString);
if (ItemToRemoveOrInsert != null)
{
filtered.Remove(ItemToRemoveOrInsert);
if (!string.IsNullOrWhiteSpace(InsertValue))
{
filtered.Add(ItemToRemoveOrInsert, InsertValue);
}
}
string StrQr = string.Join("&", filtered.AllKeys.Select(key => key + "=" + filtered[key]).ToArray());
if (!string.IsNullOrWhiteSpace(StrQr)){
StrQr="?" + StrQr;
}
return StrQr;
}

How can i access any key inside of json string via C#?

My question is simple but i can not do that. i wanna get value of "soap:Body" from below string by C#code?
{"soap:Envelope":{"xmlns:xsd":"http://www.w3.org/2001/XMLSchema","xmlns:soap":"http://www.w3.org/2003/05/soap-envelope","xmlns:xsi":"http://www.w3.org/2001/XMLSchema-instance","soap:Body":{"ToplamaResponse":{"xmlns":"http://tempuri.org/","ToplamaResult":156758}}}}

You can also use the Framework class JavaScriptSerializer if you do not want to use an external library.
string json = #"...";
JavaScriptSerializer serializer = new JavaScriptSerializer();
var o = serializer.Deserialize<dynamic>(json);
var body = o["soap:Envelope"]["soap:Body"];

You can do it easily by using Json.NET
dynamic data = JObject.Parse("{'soap:Envelope':{'xmlns:xsd':'http://www.w3.org/2001/XMLSchema','xmlns:soap':'http://www.w3.org/2003/05/soap-envelope','xmlns:xsi':'http://www.w3.org/2001/XMLSchema-instance','soap:Body':{'ToplamaResponse':{'xmlns':'http://tempuri.org/','ToplamaResult':156758}}}}");
string soap_body = data["soap:Envelope"]["soap:Body"];

There is a simple example in the JObject.Parse documentation
string json = #"{
"soap:Envelope": {
"xmlns:xsd": "http://www.w3.org/2001/XMLSchema",
"xmlns:soap": "http://www.w3.org/2003/05/soap-envelope",
"xmlns:xsi": "http://www.w3.org/2001/XMLSchema-instance",
"soap:Body": {
"ToplamaResponse": {
"xmlns": "http://tempuri.org/",
"ToplamaResult": 156758
}
}
}
}";
JObject obj = JObject.Parse(json);
Console.WriteLine((string)obj["soap:Envelope"]["soap:Body"]);
And if you want to manipulate the value of "soap:Body" do the same thing :)

Easiest way to parse "querystring" formatted data

With the following code:
string q = "userID=16555&gameID=60&score=4542.122&time=343114";
What would be the easiest way to parse the values, preferably without writing my own parser? I'm looking for something with the same functionality as Request.querystring["gameID"].

Pretty easy... Use the HttpUtility.ParseQueryString method.
Untested, but this should work:
var qs = "userID=16555&gameID=60&score=4542.122&time=343114";
var parsed = HttpUtility.ParseQueryString(qs);
var userId = parsed["userID"];
// ^^^^^^ Should be "16555". Note this will be a string of course.

You can do it with linq like this.
string query = "id=3123123&userId=44423&format=json";
Dictionary<string,string> dicQueryString =
query.Split('&')
.ToDictionary(c => c.Split('=')[0],
c => Uri.UnescapeDataString(c.Split('=')[1]));
string userId = dicQueryString["userID"];
Edit
If you can use HttpUtility.ParseQueryString then it will be a lot more straight forward and it wont be case-sensitive as in case of LinQ.

As has been mentioned in each of the previous answers, if you are in a context where you can add a dependency to the System.Web library, using HttpUtility.ParseQueryString makes sense. (For reference, the relevant source can be found in the Microsoft Reference Source). However, if this is not possible, I would like to propose the following modification to Adil's answer which accounts for many of the concerns addressed in the comments (such as case sensitivity and duplicate keys):
var q = "userID=16555&gameID=60&score=4542.122&time=343114";
var parsed = q.TrimStart('?')
.Split(new[] { '&' }, StringSplitOptions.RemoveEmptyEntries)
.Select(k => k.Split('='))
.Where(k => k.Length == 2)
.ToLookup(a => a[0], a => Uri.UnescapeDataString(a[1])
, StringComparer.OrdinalIgnoreCase);
var userId = parsed["userID"].FirstOrDefault();
var time = parsed["TIME"].Select(v => (int?)int.Parse(v)).FirstOrDefault();

If you want to avoid the dependency on System.Web that is required to use HttpUtility.ParseQueryString, you could use the Uri extension method ParseQueryString found in System.Net.Http.
Note that you have to convert the response body to a valid Uri so that ParseQueryString works.
Please also note in the MSDN document, this method is an extension method for the Uri class, so you need reference the assembly System.Net.Http.Formatting (in System.Net.Http.Formatting.dll). I tried installed it by the nuget package with the name "System.Net.Http.Formatting", and it works fine.
string body = "value1=randomvalue1&value2=randomValue2";
// "http://localhost/query?" is added to the string "body" in order to create a valid Uri.
string urlBody = "http://localhost/query?" + body;
NameValueCollection coll = new Uri(urlBody).ParseQueryString();

How is this
using System.Text.RegularExpressions;
// query example
// "name1=value1&name2=value2&name3=value3"
// "?name1=value1&name2=value2&name3=value3"
private Dictionary<string, string> ParseQuery(string query)
{
var dic = new Dictionary<string, string>();
var reg = new Regex("(?:[?&]|^)([^&]+)=([^&]*)");
var matches = reg.Matches(query);
foreach (Match match in matches) {
dic[match.Groups[1].Value] = Uri.UnescapeDataString(match.Groups[2].Value);
}
return dic;
}

System.Net.Http ParseQueryString extension method worked for me. I'm using OData query options and trying to parse out some custom parameters.
options.Request.RequestUri.ParseQueryString();
Seems to give me what I need.

HttpUtility.ParseQueryString will work as long as you are in a web app or don't mind including a dependency on System.Web. Another way to do this is:
// NameValueCollection nameValueCollection = HttpUtility.ParseQueryString(queryString);
NameValueCollection nameValueCollection = new NameValueCollection();
string[] querySegments = queryString.Split('&');
foreach(string segment in querySegments)
{
string[] parts = segment.Split('=');
if (parts.Length > 0)
{
string key = parts[0].Trim(new char[] { '?', ' ' });
string val = parts[1].Trim();
nameValueCollection.Add(key, val);
}
}

For .NET Core there is Microsoft.AspNetCore.WebUtilities.QueryHelpers.ParseQuery
var queryString = QueryHelpers.ParseQuery("?param1=value");
var queryParamValue = queryString["param1"];
Code snippet modified from trackjs.com:

How to deserialize currencies list from openexchangerates.org to C# custom class or object?

I need to get currency values list in C# from here:
http://openexchangerates.org/currencies.json
which produces this kind of output:
{
"AED": "United Arab Emirates Dirham",
"AFN": "Afghan Afghani",
"ALL": "Albanian Lek",
"AMD": "Armenian Dram",
"ANG": "Netherlands Antillean Guilder",
"AOA": "Angolan Kwanza"
// and so on
}
I managed to get a string containing values above using C#, but I cannot find a way to deserialize that string into any custom class or anonymous object, so I am wondering how to do that?
Also, I am trying to use Json.NET to do that, but so far couldn't find a solution...

using Json.Net
var dict = JsonConvert.DeserializeObject<Dictionary<string, string>>(jsonString);
--EDIT--
You can make it shorter
WebClient w = new WebClient();
string url = "http://openexchangerates.org/currencies.json";
var dict = JsonConvert.DeserializeObject<Dictionary<string, string>>(w.DownloadString(url));

A solution using only .Net 4.0 and no third party libraries:
string url = "http://openexchangerates.org/currencies.json";
var client = new System.Net.WebClient();
string curStr = client.DownloadString(url);
var js = new System.Web.Script.Serialization.JavaScriptSerializer();
var res = (js.DeserializeObject(curStr) as Dictionary<string, object>)
.Select(x => new { CurKey = x.Key, Currency = x.Value.ToString() });
Outputs a list of anonymous objects with the keys and values from the list as properties.
Enjoy :)

JSON Deserialization: How to get values out of a JSON array of objects

I've successfully deserialized this JSON string in C#, but can't extract the values from the objects nested in the array:
JavaScriptSerializer js = new JavaScriptSerializer();
string json =
{"key":"1234","status":"ok","members":
[{"id":7,"name":"Joe"},
{"id":2,"name":"Robert"},
{"id":18,"name":"Tim"}
]
}
var d = js.Deserialize < dynamic > (json);
string _key = d["key"]; // this works
Array _members = d["members"]; // this works, length = 3
But I'm having trouble extracting the values out of the objects by name, e.g, this isn't right, but essentially I want
_members[0]["name"] or, _members[0].name
I think the deserializer makes the objects inside the array dictionaries, but I think I'm clearing missing something...

I recommend using Json.NET to do what you're doing. The following code does what you want:
JObject jObject = JObject.Parse(json);
JToken memberName = jObject["members"].First["name"];
Console.WriteLine(memberName); // Joe
Via LINQ to Json.
Update:
var js = new JavaScriptSerializer();
var d = js.Deserialize<dynamic>(json);
Console.WriteLine(d["members"][0]["name"]); // Joe
Also works fine.

It's a bit late for an answer but I've been trying to figure this out and thought I should post somewhere what worked for me.
I wanted to use foreach so:
foreach (var member in json["members"])
{
Console.WriteLine(member["name"]);
}
and by the way, (for some reason like in my project) if you have nested arrays, e.g.
string json =
{"key":"1234","status":"ok",
"members":[
{"items"[
{"id":7,"name":"Joe"},
{"id":2,"name":"Robert"},
{"id":18,"name":"Tim"}
]}
]}
Then:
foreach (var member in json["members"])
{
foreach (var item in member["items"])
{
Console.WriteLine(item["name"]);
}
}

You were quite close in syntax. The key here is that d["members"] is of type Object[] / object[]. Instead of Array, you can use dynamic[] and everything works just fine.
Also note that even this declaration isn't explicitly necessary, as shown in DPeden's updated sample.
Here is the code for your updated snippet (I used a console app to test):
JavaScriptSerializer js = new JavaScriptSerializer();
dynamic d = js.Deserialize<dynamic>(json);
string key = d["key"];
string status = d["status"];
dynamic[] members = d["members"];
Console.WriteLine("key = {0}", key);
Console.WriteLine("status = {0}", status);
Console.WriteLine("members.length = {0}", members.Length);
Console.WriteLine("members type name = {0}", members.GetType().Name);
Console.WriteLine("d[\"members\"] type name = {0}", d["members"].GetType().Name);
And here is additional code showing array and member access.
Console.WriteLine("--");
for (int i = 0; i < members.Length; i++)
{
Console.WriteLine("members[{0}][\"id\"] = {1}", i, members[i]["id"]);
Console.WriteLine("members[{0}][\"name\"] = {1}", i, members[i]["name"]);
}
Console.WriteLine("--");
Console.WriteLine("{0}", d["members"][0]["id"]);
Console.WriteLine("{0}", d["members"][0]["name"]);
Console.ReadKey();