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my question is simple but I got stuck with something. Can you tell me how can I reduce 2 select into 1 select LINQ in c#? I am using CloudNative.CloudEvents NuGet package for cloud-native events.
var orderEvents = input
.Select(_ => new OrderDocument(_.Id, _.ToString()).ToOrderEvent())
.Select(_ =>
new CloudEvent()
{
Type = _.EventType,
Subject = _.Subject,
Source = _.Source,
Data = _
});
input is a parameter from cosmosDbTrigger it`s type : IReadOnlyList
OrderDocument.cs
public class OrderDocument
{
public string Id { get; private set; }
public string Json { get; private set; }
public OrderDocument(string id, string json)
{
Id = id;
Json = json;
}
public OrderEvent ToOrderEvent() => OrderEventHelper.ToOrderEvent(Json);
}
OrderEventHelper.cs
public static OrderEvent ToOrderEvent(string json)
{
ArgumentHelper.ThrowIfNullOrEmpty(json);
var orderEvent = JsonConvert.DeserializeObject<OrderEvent>(json);
var eventDefinition = OrderEvents.EventDefinitions.SingleOrDefault(_ => _.EventType == orderEvent.EventType);
return eventDefinition == null
? orderEvent
: new OrderEvent(
orderEvent.Id,
orderEvent.Source,
orderEvent.EventType,
orderEvent.Subject,
orderEvent.DataContentType,
orderEvent.DataSchema,
orderEvent.Timestamp,
JsonConvert.DeserializeObject(orderEvent.Payload.ToString(), eventDefinition.PayloadType),
orderEvent.TraceId);
}
linq extensions are basically for loops in the background. If you want to perform multiple actions against a list, perhaps making your own simple for loop where you can manage that yourself would work.
Your code:
var orderEvents = input
.Select(_ => new OrderDocument(_.Id, _.ToString()).ToOrderEvent())
.Select(_ =>
new CloudEvent()
{
Type = _.EventType,
Subject = _.Subject,
Source = _.Source,
Data = _
});
could be changed to:
// our result set, rather than the one returned from linq Select
var results = new List<CloudEvent>();
foreach(var x in input){
// create the order event here
var temporaryOrderEvent = new OrderDocument(x.Id, x.ToString()).ToOrderEvent();
// add the Cloud event to our result set
results.Add(new CloudEvent()
{
Type = temporaryOrderEvent .EventType,
Subject = temporaryOrderEvent .Subject,
Source = temporaryOrderEvent .Source,
Data = temporaryOrderEvent
});
}
where you then have a result list to work with.
If you wanted to keep it all in linq, you could instead perform all of your logic in the first Select, and ensure that it returns a CloudEvent. Notice here that you can employ the use of curly brackets in the linq statement to evaluate a function rather than a single variable value:
var orderEvents = input
.Select(x =>
{
// create the order event here
var temporaryOrderEvent = new OrderDocument(x.Id, x.ToString()).ToOrderEvent();
// return the Cloud event here
return new CloudEvent()
{
Type = temporaryOrderEvent .EventType,
Subject = temporaryOrderEvent .Subject,
Source = temporaryOrderEvent .Source,
Data = temporaryOrderEvent
};
});
How about putting conversion to OrderEvent and using ToCloudEvent in the same Select?
var orderEvents = input
.Select(_ => new OrderDocument(_.Id, _.ToString()).ToOrderEvent().ToCloudEvent())
public class OrderEvent
{
public CloudEvent ToCloudEvent()
{
new CloudEvent()
{
Type = this.EventType,
Subject = this.Subject,
Source = this.Source,
Data = this
};
}
}
I'm trying to program an API for discord and I need to retrieve two pieces of information out of the HTML code of the web page https://myanimelist.net/character/214 (and other similar pages with URLs of the form https://myanimelist.net/character/N for integers N), specifically the URL of the Character Picture (in this case https://cdn.myanimelist.net/images/characters/14/54554.jpg) and the name of the character (in this case Youji Kudou). Afterwards I need to save those two pieces of information to JSON.
I am using HTMLAgilityPack for this, yet I can't quite see through it. The following is my first attempt:
public static void Main()
{
var html = "https://myanimelist.net/character/214";
HtmlWeb web = new HtmlWeb();
var htmlDoc = web.Load(html);
var htmlNodes = htmlDoc.DocumentNode.SelectNodes("//body");
foreach (var node in htmlNodes.Descendants("tr/td/div/a/img"))
{
Console.WriteLine(node.InnerHtml);
}
}
Unfortunately, this produces no output. If I followed the path correctly (which is probably the first mistake) it should be "tr/td/div/a/img". I get no errors, it runs, yet I get no output.
My second attempt is:
public static void Main()
{
var html = "https://myanimelist.net/character/214";
HtmlWeb web = new HtmlWeb();
var htmlDoc = web.Load(html);
var htmlNodes = htmlDoc.DocumentNode.SelectNodes("//body");
HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();
var script = htmlDoc.DocumentNode.Descendants()
.Where(n => n.Name == "tr/td/a/img")
.First().InnerText;
// Return the data of spect and stringify it into a proper JSON object
var engine = new Jurassic.ScriptEngine();
var result = engine.Evaluate("(function() { " + script + " return src; })()");
var json = JSONObject.Stringify(engine, result);
Console.WriteLine(json);
Console.ReadKey();
}
But this also doesn't work.
How can I extract the required information?
EDIT:
So, I've come quite further now, and I've found a solution to finding the link. It was rather simple. But now I'm stuck with finding the name of the character. The website is structured the same on every other link there is (changing the last number) so, I want to find many different ones via for loop. Here's how I tried to do it:
for (int i = 1; i <= 1000; i++)
{
HtmlWeb web = new HtmlWeb();
var html = "https://myanimelist.net/character/" + i;
var htmlDoc = web.Load(html);
foreach (var item in htmlDoc.DocumentNode.SelectNodes("//*[#]"))
{
string n;
n = item.GetAttributeValue("src", "");
foreach (var item2 in htmlDoc.DocumentNode.SelectNodes("//*[#src and #alt='" + n + "']"))
{
Console.WriteLine(item2.GetAttributeValue("src", ""));
}
}
}
in the first foreach I would try to search for the name, which is concluded always at the same position (e.g http://prntscr.com/o1uo3c and http://prntscr.com/o1uo91 and to be specific: http://prntscr.com/o1xzbk) but I haven't found out how yet. Since the structure in the HTML doesn't have any body type I can follow up with. The second foreach loop is to search for the URL which works by now and the n should give me the name, so I can figure it out for each different character.
I was able to extract the character name and image from https://myanimelist.net/character/214 using the following method:
public static CharacterData ExtractCharacterNameAndImage(string url)
{
//Use the following if you are OK with hardcoding the structure of <div> elements.
//var tableXpath = "/html/body/div[1]/div[3]/div[3]/div[2]/table";
//Use the following if you are OK with hardcoding the fact that the relevant table comes first.
var tableXpath = "/html/body//table";
var nameXpath = "tr/td[2]/div[4]";
var imageXpath = "tr/td[1]/div[1]/a/img";
var htmlDoc = new HtmlWeb().Load(url);
var table = htmlDoc.DocumentNode.SelectNodes(tableXpath).First();
var name = table.SelectNodes(nameXpath).Select(n => n.GetDirectInnerText().Trim()).SingleOrDefault();
var imageUrl = table.SelectNodes(imageXpath).Select(n => n.GetAttributeValue("src", "")).SingleOrDefault();
return new CharacterData { Name = name, ImageUrl = imageUrl, Url = url };
}
Where CharacterData is defined as follows:
public class CharacterData
{
public string Name { get; set; }
public string ImageUrl { get; set; }
public string Url { get; set; }
}
Afterwards, the character data can be serialized to JSON using any of the tools from How to write a JSON file in C#?, e.g. json.net:
var url = "https://myanimelist.net/character/214";
var data = ExtractCharacterNameAndImage(url);
var json = JsonConvert.SerializeObject(data, Formatting.Indented);
Console.WriteLine(json);
Which outputs
{
"Name": "Youji Kudou",
"ImageUrl": "https://cdn.myanimelist.net/images/characters/14/54554.jpg",
"Url": "https://myanimelist.net/character/214"
}
If you would prefer the Name to include the Japanese in parenthesis, replace GetDirectInnerText() with just InnerText, which results in:
{
"Name": "Youji Kudou (工藤耀爾)",
"ImageUrl": "https://cdn.myanimelist.net/images/characters/14/54554.jpg",
"Url": "https://myanimelist.net/character/214"
}
Alternatively, if you prefer you could pull the character name from the document title:
var title = string.Concat(htmlDoc.DocumentNode.SelectNodes("/html/head/title").Select(n => n.InnerText.Trim()));
var index = title.IndexOf("- MyAnimeList.net");
if (index >= 0)
title = title.Substring(0, index).Trim();
How did I determine the correct XPath strings?
Firstly, using Firefox 66, I opened the debugger and loaded https://myanimelist.net/character/214 in the window with the debugging tools visible.
Next, following the instructions from How to find xpath of an element in firefox inspector, I selected the Youji Kudou (工藤耀爾) node and copied its XPath, which turned out to be:
/html/body/div[1]/div[3]/div[3]/div[2]/table/tbody/tr/td[2]/div[4]
I then tried to select this node using SelectNodes()... and got a null result. But why? To determine this I created a debugging routine that would break the path into successively longer portions and determine where the failure occurs:
static void TestSelect(HtmlDocument htmlDoc, string xpath)
{
Console.WriteLine("\nInput path: " + xpath);
var splitPath = xpath.Split('/');
for (int i = 2; i <= splitPath.Length; i++)
{
if (splitPath[i-1] == "")
continue;
var thisPath = string.Join("/", splitPath, 0, i);
Console.Write("Testing \"{0}\": ", thisPath);
var result = htmlDoc.DocumentNode.SelectNodes(thisPath);
Console.WriteLine("result count = {0}", result == null ? "null" : result.Count.ToString());
}
}
This output the following:
Input path: /html/body/div[1]/div[3]/div[3]/div[2]/table/tbody/tr/td[2]/div[4]
Testing "/html": result count = 1
Testing "/html/body": result count = 1
Testing "/html/body/div[1]": result count = 1
Testing "/html/body/div[1]/div[3]": result count = 1
Testing "/html/body/div[1]/div[3]/div[3]": result count = 1
Testing "/html/body/div[1]/div[3]/div[3]/div[2]": result count = 1
Testing "/html/body/div[1]/div[3]/div[3]/div[2]/table": result count = 1
Testing "/html/body/div[1]/div[3]/div[3]/div[2]/table/tbody": result count = null
Testing "/html/body/div[1]/div[3]/div[3]/div[2]/table/tbody/tr": result count = null
Testing "/html/body/div[1]/div[3]/div[3]/div[2]/table/tbody/tr/td[2]": result count = null
Testing "/html/body/div[1]/div[3]/div[3]/div[2]/table/tbody/tr/td[2]/div[4]": result count = null
As you can see, something goes wrong selecting the <tbody> path element. Manual inspection of the InnerHtml returned by selecting /html/body/div[1]/div[3]/div[3]/div[2]/table revealed that, for some reason, the server is not including the <tbody> tag when returning HTML to the HtmlWeb object -- possibly due to some difference in request header(s) provided by Firefox vs HtmlWeb. Once I omitted the tbody path element I was able to query for the character name successfully using:
/html/body/div[1]/div[3]/div[3]/div[2]/table/tr/td[2]/div[4]
A similar process provided the following working path for the image:
/html/body/div[1]/div[3]/div[3]/div[2]/table/tr/td[1]/div[1]/a/img
Since the two queries are finding contents in the same <table>, in my final code I selected the table only once in a separate step, and removed some of the hardcoding as to the specific nesting of <div> elements.
Demo fiddle here.
Alright, to finnish it up, I've rounded the Code, gratefully assisted by dbc, and implemented nearly completly into the project. Just if someone in later days maybe has a identical question, here they go. This outputs out of a defined number all the character names, links and images and writes it into a JSON file and could be adapted for other websites.
using System;
using System.Linq;
using Newtonsoft.Json;
using HtmlAgilityPack;
using System.IO;
namespace SearchingHTML
{
public class CharacterData
{
public string Name { get; set; }
public string ImageUrl { get; set; }
public string Url { get; set; }
}
public class Program
{
public static CharacterData ExtractCharacterNameAndImage(string url)
{
var tableXpath = "/html/body//table";
var nameXpath = "tr/td[2]/div[4]";
var imageXpath = "tr/td[1]/div[1]/a/img";
var htmlDoc = new HtmlWeb().Load(url);
var table = htmlDoc.DocumentNode.SelectNodes(tableXpath).First();
var name = table.SelectNodes(nameXpath).Select(n => n.GetDirectInnerText().Trim()).SingleOrDefault();
var imageUrl = table.SelectNodes(imageXpath).Select(n => n.GetAttributeValue("src", "")).SingleOrDefault();
return new CharacterData { Name = name, ImageUrl = imageUrl, Url = url };
}
public static void Main()
{
int max = 10000;
string fileName = #"C:\Users\path of your file.json";
Console.WriteLine("Environment version: " + Environment.Version);
Console.WriteLine("Json.NET version: " + typeof(JsonSerializer).Assembly.FullName);
Console.WriteLine("HtmlAgilityPack version: " + typeof(HtmlDocument).Assembly.FullName);
Console.WriteLine();
for (int i = 6; i <= max; i++)
{
try
{
var url = "https://myanimelist.net/character/" + i;
var htmlDoc = new HtmlWeb().Load(url);
var data = ExtractCharacterNameAndImage(url);
var json = JsonConvert.SerializeObject(data, Formatting.Indented);
Console.WriteLine(json);
TextWriter tsw = new StreamWriter(fileName, true);
tsw.WriteLine(json);
tsw.Close();
} catch (Exception ex) { }
}
}
}
}
/*******************************************************************************************************************************
****************************************************IF TESTING IS REQUIERED****************************************************
*******************************************************************************************************************************
*
* static void TestSelect(HtmlDocument htmlDoc, string xpath)
Console.WriteLine("\nInput path: " + xpath);
var splitPath = xpath.Split('/');
for (int i = 2; i <= splitPath.Length; i++)
{
if (splitPath[i - 1] == "")
continue;
var thisPath = string.Join("/", splitPath, 0, i);
Console.Write("Testing \"{0}\": ", thisPath);
var result = htmlDoc.DocumentNode.SelectNodes(thisPath);
Console.WriteLine("result count = {0}", result == null ? "null" : result.Count.ToString());
}
}
*******************************************************************************************************************************
*********************************************FOR TESTING ENTER THIS INTO MAIN CLASS********************************************
*******************************************************************************************************************************
*
* var url2 = "https://myanimelist.net/character/256";
var data2 = ExtractCharacterNameAndImage(url2);
var json2 = JsonConvert.SerializeObject(data2, Formatting.Indented);
Console.WriteLine(json2);
var nameXpathFromFirefox = "/html/body/div[1]/div[3]/div[3]/div[2]/table/tbody/tr/td[2]/div[4]";
var imageXpathFromFirefox = "/html/body/div[1]/div[3]/div[3]/div[2]/table/tbody/tr/td[1]/div[1]/a/img";
TestSelect(htmlDoc, nameXpathFromFirefox);
TestSelect(htmlDoc, imageXpathFromFirefox);
var nameXpathFromFirefoxFixed = "/html/body/div[1]/div[3]/div[3]/div[2]/table/tr/td[2]/div[4]";
var imageXpathFromFirefoxFixed = "/html/body/div[1]/div[3]/div[3]/div[2]/table/tr/td[1]/div[1]/a/img";
TestSelect(htmlDoc, nameXpathFromFirefoxFixed);
TestSelect(htmlDoc, imageXpathFromFirefoxFixed);
*******************************************************************************************************************************
*******************************************************************************************************************************
*******************************************************************************************************************************
*/
I have no problem deserializing a single json object
string json = #"{'Name':'Mike'}";
to a C# anonymous type:
var definition = new { Name = ""};
var result = JsonConvert.DeserializeAnonymousType(json, definition);
But when I have an array:
string jsonArray = #"[{'Name':'Mike'}, {'Name':'Ben'}, {'Name':'Razvigor'}]";
I am stuck.
How can it be done?
The solution is:
string json = #"[{'Name':'Mike'}, {'Name':'Ben'}, {'Name':'Razvigor'}]";
var definition = new[] { new { Name = "" } };
var result = JsonConvert.DeserializeAnonymousType(json, definition);
Of course, since result is an array, you'll access individual records like so:
string firstResult = result[0].Name;
You can also call .ToList() and similar methods on it.
You can deserialize to dynamic object by this.
dynamic result = JsonConvert.DeserializeObject(jsonArray);
One approach is to put an identifier in your JSON array string.
This code worked for me:
var typeExample = new { names = new[] { new { Name = "" } } };
string jsonArray = #"{ names: [{'Name':'Mike'}, {'Name':'Ben'}, {'Name':'Razvigor'}]}";
var result = JsonConvert.DeserializeAnonymousType(jsonArray, typeExample);
Here I am storing two set of querystring parameters into two different namevalue collection. The querystring parameter order may vary so I just want to sort the order and then I need to store namevalue collection to a string.
Updated Code :
string url1 = #"http://www.somewebsitesampletest.com/dcs7o?data=142248494&dcp=smre&nparam=4567P&email=xxx.com";
string url2 = #"http://www.somewebsitesampletest.com/dcs7o?dcp=smre&data=142248494&email=xxx.com&nparam=4567P";
var NameValueCollection1 = HttpUtility.ParseQueryString(url1);
var NameValueCollection2 = HttpUtility.ParseQueryString(url2);
ExpectedResult:
After Sorting and converting to string the result should look like the below one
string query1 = "data=142248494&dcp=smre&email=xxx.com&nparam=4567P";
string query2 = "data=142248494&dcp=smre&email=xxx.com&nparam=4567P";
Here's a solution using Linq.
Basically it changes the NameValueCollection to an IEnumerable of the keys using Cast<T>, then the rest is fairly self explanatory.
public string GetSortedQueryString(string url)
{
var queryString = HttpUtility.ParseQueryString(url);
// Ignore null keys (caused by your ?& at the start of the query string
var orderedKeys = queryString.Cast<string>().Where(k => k != null).OrderBy(k => k);
return string.Join("&", orderedKeys.Select(k => string.Format("{0}={1}", k, queryString[k])));
}
Results for your URLs would be:
data=142248494&dcp=smre&email=xxx.com&nparam=4567P
data=142248494&dcp=smre&email=xxx.com&nparam=4567P
Email comes before nparam, unlike your expected solution (I'm assuming that was a mistake).
use LINQ with a Dictionary and a list of KeyValuePair :
string url1 = #"http://www.somewebsitesampletest.com/dcs7o?&data=142248494&dcp=smre&nparam=4567P&email=xxx.com";
string query1 ="";
Dictionary<String, String> paramDict = new Dictionary<string, string>();
var query = from match in urlString.Split('?').Where(m => m.Contains('='))
.SelectMany(pr => pr.Split('&'))
where match.Contains('=')
select new KeyValuePair<string, String>(
match.Split('=')[0],
match.Split('=')[1]);
query.ToList().ForEach(kvp => paramDict.Add(kvp.Key, kvp.Value));
var List<KeyValuePair<string, string>> paramList = paramDict.ToList();
paramList.Sort();
foreach (KeyValuePair<string, int> pair in list)
{
query1+=pair.Key+"="+pair.Value+"&";
}
query1=query1.TrimEnd('&');
I made this fiddle because I needed to sort querystring values in order to properly compare URIs: (H/T to Jacob's answer)
https://dotnetfiddle.net/eEhkNk
This preserves duplicate keys:
public static string[] QueryStringOmissions = new string[] { "b" };
public static NameValueCollection SortAndRemove(NameValueCollection collection)
{
var orderedKeys = collection.Cast<string>().Where(k => k != null).OrderBy(k => k);
var newCollection = HttpUtility.ParseQueryString(String.Empty);
foreach(var key in orderedKeys)
{
if (!QueryStringOmissions.Contains(key))
{
foreach(var val in collection.GetValues(key).Select(x => x).OrderBy(x => x).ToArray())
{
newCollection.Add(key, val);
}
}
}
return newCollection;
}
I've got a string in .NET which is actually a URL. I want an easy way to get the value from a particular parameter.
Normally, I'd just use Request.Params["theThingIWant"], but this string isn't from the request. I can create a new Uri item like so:
Uri myUri = new Uri(TheStringUrlIWantMyValueFrom);
I can use myUri.Query to get the query string...but then I apparently have to find some regexy way of splitting it up.
Am I missing something obvious, or is there no built in way to do this short of creating a regex of some kind, etc?
Use static ParseQueryString method of System.Web.HttpUtility class that returns NameValueCollection.
Uri myUri = new Uri("http://www.example.com?param1=good¶m2=bad");
string param1 = HttpUtility.ParseQueryString(myUri.Query).Get("param1");
Check documentation at http://msdn.microsoft.com/en-us/library/ms150046.aspx
This is probably what you want
var uri = new Uri("http://domain.test/Default.aspx?var1=true&var2=test&var3=3");
var query = HttpUtility.ParseQueryString(uri.Query);
var var2 = query.Get("var2");
Here's another alternative if, for any reason, you can't or don't want to use HttpUtility.ParseQueryString().
This is built to be somewhat tolerant to "malformed" query strings, i.e. http://test/test.html?empty= becomes a parameter with an empty value. The caller can verify the parameters if needed.
public static class UriHelper
{
public static Dictionary<string, string> DecodeQueryParameters(this Uri uri)
{
if (uri == null)
throw new ArgumentNullException("uri");
if (uri.Query.Length == 0)
return new Dictionary<string, string>();
return uri.Query.TrimStart('?')
.Split(new[] { '&', ';' }, StringSplitOptions.RemoveEmptyEntries)
.Select(parameter => parameter.Split(new[] { '=' }, StringSplitOptions.RemoveEmptyEntries))
.GroupBy(parts => parts[0],
parts => parts.Length > 2 ? string.Join("=", parts, 1, parts.Length - 1) : (parts.Length > 1 ? parts[1] : ""))
.ToDictionary(grouping => grouping.Key,
grouping => string.Join(",", grouping));
}
}
Test
[TestClass]
public class UriHelperTest
{
[TestMethod]
public void DecodeQueryParameters()
{
DecodeQueryParametersTest("http://test/test.html", new Dictionary<string, string>());
DecodeQueryParametersTest("http://test/test.html?", new Dictionary<string, string>());
DecodeQueryParametersTest("http://test/test.html?key=bla/blub.xml", new Dictionary<string, string> { { "key", "bla/blub.xml" } });
DecodeQueryParametersTest("http://test/test.html?eins=1&zwei=2", new Dictionary<string, string> { { "eins", "1" }, { "zwei", "2" } });
DecodeQueryParametersTest("http://test/test.html?empty", new Dictionary<string, string> { { "empty", "" } });
DecodeQueryParametersTest("http://test/test.html?empty=", new Dictionary<string, string> { { "empty", "" } });
DecodeQueryParametersTest("http://test/test.html?key=1&", new Dictionary<string, string> { { "key", "1" } });
DecodeQueryParametersTest("http://test/test.html?key=value?&b=c", new Dictionary<string, string> { { "key", "value?" }, { "b", "c" } });
DecodeQueryParametersTest("http://test/test.html?key=value=what", new Dictionary<string, string> { { "key", "value=what" } });
DecodeQueryParametersTest("http://www.google.com/search?q=energy+edge&rls=com.microsoft:en-au&ie=UTF-8&oe=UTF-8&startIndex=&startPage=1%22",
new Dictionary<string, string>
{
{ "q", "energy+edge" },
{ "rls", "com.microsoft:en-au" },
{ "ie", "UTF-8" },
{ "oe", "UTF-8" },
{ "startIndex", "" },
{ "startPage", "1%22" },
});
DecodeQueryParametersTest("http://test/test.html?key=value;key=anotherValue", new Dictionary<string, string> { { "key", "value,anotherValue" } });
}
private static void DecodeQueryParametersTest(string uri, Dictionary<string, string> expected)
{
Dictionary<string, string> parameters = new Uri(uri).DecodeQueryParameters();
Assert.AreEqual(expected.Count, parameters.Count, "Wrong parameter count. Uri: {0}", uri);
foreach (var key in expected.Keys)
{
Assert.IsTrue(parameters.ContainsKey(key), "Missing parameter key {0}. Uri: {1}", key, uri);
Assert.AreEqual(expected[key], parameters[key], "Wrong parameter value for {0}. Uri: {1}", parameters[key], uri);
}
}
}
Looks like you should loop over the values of myUri.Query and parse it from there.
string desiredValue;
foreach(string item in myUri.Query.Split('&'))
{
string[] parts = item.Replace("?", "").Split('=');
if(parts[0] == "desiredKey")
{
desiredValue = parts[1];
break;
}
}
I wouldn't use this code without testing it on a bunch of malformed URLs however. It might break on some/all of these:
hello.html?
hello.html?valuelesskey
hello.html?key=value=hi
hello.html?hi=value?&b=c
etc
#Andrew and #CZFox
I had the same bug and found the cause to be that parameter one is in fact: http://www.example.com?param1 and not param1 which is what one would expect.
By removing all characters before and including the question mark fixes this problem. So in essence the HttpUtility.ParseQueryString function only requires a valid query string parameter containing only characters after the question mark as in:
HttpUtility.ParseQueryString ( "param1=good¶m2=bad" )
My workaround:
string RawUrl = "http://www.example.com?param1=good¶m2=bad";
int index = RawUrl.IndexOf ( "?" );
if ( index > 0 )
RawUrl = RawUrl.Substring ( index ).Remove ( 0, 1 );
Uri myUri = new Uri( RawUrl, UriKind.RelativeOrAbsolute);
string param1 = HttpUtility.ParseQueryString( myUri.Query ).Get( "param1" );`
You can just use the Uri to get the list of the query strings or find a specific parameter.
Uri myUri = new Uri("http://www.example.com?param1=good¶m2=bad");
var params = myUri.ParseQueryString();
var specific = myUri.ParseQueryString().Get("param1");
var paramByIndex = myUri.ParseQueryString().Get(2);
You can find more from here: https://learn.microsoft.com/en-us/dotnet/api/system.uri?view=net-5.0
You can use the following workaround for it to work with the first parameter too:
var param1 =
HttpUtility.ParseQueryString(url.Substring(
new []{0, url.IndexOf('?')}.Max()
)).Get("param1");
Or if you don't know the URL (so as to avoid hardcoding, use the AbsoluteUri
Example ...
//get the full URL
Uri myUri = new Uri(Request.Url.AbsoluteUri);
//get any parameters
string strStatus = HttpUtility.ParseQueryString(myUri.Query).Get("status");
string strMsg = HttpUtility.ParseQueryString(myUri.Query).Get("message");
switch (strStatus.ToUpper())
{
case "OK":
webMessageBox.Show("EMAILS SENT!");
break;
case "ER":
webMessageBox.Show("EMAILS SENT, BUT ... " + strMsg);
break;
}
Use .NET Reflector to view the FillFromString method of System.Web.HttpValueCollection. That gives you the code that ASP.NET is using to fill the Request.QueryString collection.
Single line LINQ solution:
Dictionary<string, string> ParseQueryString(string query)
{
return query.Replace("?", "").Split('&').ToDictionary(pair => pair.Split('=').First(), pair => pair.Split('=').Last());
}
if you want in get your QueryString on Default page .Default page means your current page url .
you can try this code :
string paramIl = HttpUtility.ParseQueryString(this.ClientQueryString).Get("city");
This is actually very simple, and that worked for me :)
if (id == "DK")
{
string longurl = "selectServer.aspx?country=";
var uriBuilder = new UriBuilder(longurl);
var query = HttpUtility.ParseQueryString(uriBuilder.Query);
query["country"] = "DK";
uriBuilder.Query = query.ToString();
longurl = uriBuilder.ToString();
}
For anyone who wants to loop through all query strings from a string
foreach (var item in new Uri(urlString).Query.TrimStart('?').Split('&'))
{
var subStrings = item.Split('=');
var key = subStrings[0];
var value = subStrings[1];
// do something with values
}
Here is a sample that mentions what dll to include
var testUrl = "https://www.google.com/?q=foo";
var data = new Uri(testUrl);
// Add a reference to System.Web.dll
var args = System.Web.HttpUtility.ParseQueryString(data.Query);
args.Set("q", "my search term");
var nextUrl = $"{data.Scheme}://{data.Host}{data.LocalPath}?{args.ToString()}";
Easiest way how to get value of know the param name:
using System.Linq;
string loc = "https://localhost:5000/path?desiredparam=that_value&anotherParam=whatever";
var c = loc.Split("desiredparam=").Last().Split("&").First();//that_value
HttpContext.Current.Request.QueryString.Get("id");
I used it and it run perfectly
<%=Request.QueryString["id"] %>