How to efficiently remove a query string by Key fr

问题:

How to remove a query string by Key from a Url?

I have the below method which works fine but just wondering is there any better/shorter way? or a built-in .NET method which can do it more efficiently?

 public static string RemoveQueryStringByKey(string url, string key)
        {
            var indexOfQuestionMark = url.IndexOf("?");
            if (indexOfQuestionMark == -1)
            {
                return url;
            }

            var result = url.Substring(0, indexOfQuestionMark);
            var queryStrings = url.Substring(indexOfQuestionMark + 1);
            var queryStringParts = queryStrings.Split(new [] {'&'});
            var isFirstAdded = false;

            for (int index = 0; index <queryStringParts.Length; index++)
            {
                var keyValue = queryStringParts[index].Split(new char[] { '=' });
                if (keyValue[0] == key)
                {
                    continue;
                }

                if (!isFirstAdded)
                {
                    result += "?";
                    isFirstAdded = true;
                }
                else
                {
                    result += "&";
                }

                result += queryStringParts[index];
            }

            return result;
        }

For example I can call it like:

  Console.WriteLine(RemoveQueryStringByKey(@"http://www.domain.com/uk_pa/PostDetail.aspx?hello=hi&xpid=4578", "xpid"));

Hope the question is clear.

Thanks,

回答1:

This works well:

public static string RemoveQueryStringByKey(string url, string key)
{                   
    var uri = new Uri(url);

    // this gets all the query string key value pairs as a collection
    var newQueryString = HttpUtility.ParseQueryString(uri.Query);

    // this removes the key if exists
    newQueryString.Remove(key);

    // this gets the page path from root without QueryString
    string pagePathWithoutQueryString = uri.GetLeftPart(UriPartial.Path);

    return newQueryString.Count > 0
        ? String.Format("{0}?{1}", pagePathWithoutQueryString, newQueryString)
        : pagePathWithoutQueryString;
}

an example:

RemoveQueryStringByKey("https://www.google.co.uk/search?#hl=en&output=search&sclient=psy-ab&q=cookie", "q");

and returns:

https://www.google.co.uk/#hl=en&output=search&sclient=psy-ab

回答2:

We can also do it using regex

string queryString = "Default.aspx?Agent=10&Language=2"; //Request.QueryString.ToString();
string parameterToRemove="Language";   //parameter which we want to remove
string regex=string.Format("(&{0}=[^&\s]+|(?<=\?){0}=[^&\s]+&?)",parameterToRemove);   //this will not work for javascript, for javascript you can do following
string finalQS = Regex.Replace(queryString, regex, "");

//javascript(following is not js syntex, just want to give idea how we can able do it in js)
string regex1 = string.Format("(&{0}=[^&\s]+)",parameterToRemove);
string regex2 = string.Format("(\?{0}=[^&\s]+&?)",parameterToRemove);
string finalQS = Regex.Replace(queryString, regex1, "").Replace(queryString, regex2, "");

https://regexr.com/3i9vj

回答3:

var qs = System.Web.HttpUtility.ParseQueryString(queryString);
var str = qs.Get(key);

This helper class also has Set methods.

回答4:

How about this:

        string RemoveQueryStringByKey(string url, string key)
    {
        string ret = string.Empty;

        int index = url.IndexOf(key);
        if (index > -1)
        {
            string post = string.Empty;

            // Find end of key's value
            int endIndex = url.IndexOf('&', index);
            if (endIndex != -1) // Last query string value?
            {
                post = url.Substring(endIndex, url.Length - endIndex);
            }

            // Decrement for ? or & character
            --index;
            ret = url.Substring(0, index) + post;
        }

        return ret;
    }

回答5:

I found a way without using Regex:

private string RemoveQueryStringByKey(string sURL, string sKey) {
    string sOutput = string.Empty;

    int iQuestion = sURL.IndexOf('?');
    if (iQuestion == -1) return (sURL);

    int iKey = sURL.Substring(iQuestion).IndexOf(sKey) + iQuestion;
    if (iKey == -1) return (sURL);

    int iNextAnd = sURL.Substring(iKey).IndexOf('&') + iKey + 1;

    if (iNextAnd == -1) {
        sOutput = sURL.Substring(0, iKey - 1);
    }
    else {
        sOutput = sURL.Remove(iKey, iNextAnd - iKey);
    }

    return (sOutput);
}

I did try this with adding another field at the end, and it works fine for that too.

回答6:

There's a useful class called UriBuilder in the System namespace. We can use it along with a couple of extension methods to do the following:

Uri u = new Uri("http://example.com?key1=value1&key2=value2");
u = u.DropQueryItem("key1");

Or like this:

Uri u = new Uri("http://example.com?key1=value1&key2=value2");
UriBuilder b = new UriBuilder(u);
b.RemoveQueryItem("key1");
u = b.Uri;

The extension methods:

using System;
using System.Collections.Specialized;
using System.Text;
using System.Text.RegularExpressions;

public static class UriExtensions
{
    public static Uri DropQueryItem(this Uri u, string key)
    {
        UriBuilder b = new UriBuilder(u);
        b.RemoveQueryItem(key);
        return b.Uri;
    }
}
public static class UriBuilderExtensions
{
    private static string _ParseQueryPattern = @"(?<key>[^&=]+)={0,1}(?<value>[^&]*)";
    private static Regex _ParseQueryRegex = null;

    private static Regex ParseQueryRegex
    {
        get
        {
            if (_ParseQueryRegex == null)
            {
                _ParseQueryRegex = new Regex(_ParseQueryPattern, RegexOptions.Compiled | RegexOptions.Singleline);
            }
            return _ParseQueryRegex;

        }
    }

    public static void SetQueryItem(this UriBuilder b, string key, string value)
    {
        NameValueCollection parms = ParseQueryString(b.Query);
        parms[key] = value;
        b.Query = RenderQuery(parms);
    }

    public static void RemoveQueryItem(this UriBuilder b, string key)
    {
        NameValueCollection parms = ParseQueryString(b.Query);
        parms.Remove(key);
        b.Query = RenderQuery(parms);
    }       
    private static string RenderQuery(NameValueCollection parms)
    {
        StringBuilder sb = new StringBuilder();
        for (int i=0; i<parms.Count; i++)
        {
            string key = parms.Keys[i];
            sb.Append(key + "=" + parms[key]);
            if (i < parms.Count - 1)
            {
                sb.Append("&");
            }
        }
        return sb.ToString();
    }
    public static NameValueCollection ParseQueryString(string query, bool caseSensitive = true)
    {
        NameValueCollection pairs = new NameValueCollection(caseSensitive ? StringComparer.Ordinal : StringComparer.OrdinalIgnoreCase);

        string q = query.Trim().TrimStart(new char[] {'?'});
        MatchCollection matches = ParseQueryRegex.Matches(q);

        foreach (Match m in matches)
        {
            string key = m.Groups["key"].Value;
            string value = m.Groups["value"].Value;
            if (pairs[key] != null)
            {
                pairs[key] = pairs[key] + "," + value;
            }
            else
            {
                pairs[key] = value;
            }

        }

        return pairs;

    }

}

回答7:

I'm thinking the shortest way (that I believe produces a valid URL in all cases, assuming the URL was valid to begin with) would be to use this regex (where getRidOf is the variable name you are trying to remove) and the replacement is a zero-length string ""):

(?<=[?&])getRidOf=[^&]*(&|$)

or maybe even

\bgetRidOf=[^&]*(&|$)

while possibly not the absolute prettiest URLs, I think they are all valid:

         INPUT                                         OUTPUT
      -----------                                   ------------
blah.com/blah.php?getRidOf=d.co&blah=foo        blah.com/blah.php?blah=foo
blah.com/blah.php?f=0&getRidOf=d.co&blah=foo    blah.com/blah.php?f=0&blah=foo
blah.com/blah.php?hello=true&getRidOf=d.co      blah.com/blah.php?hello=true&
blah.com/blah.php?getRidOf=d.co                 blah.com/blah.php?

and it's a simple regex replace:

Dim RegexObj as Regex = New Regex("(?<=[?&])getRidOf=[^&]*(&|$)")
RegexObj.Replace("source.url.com/find.htm?replace=true&getRidOf=PLEASE!!!", "")

...should result in the string:

"source.url.com/find.htm?replace=true&"

...which seems to be valid for an ASP.Net application, while replace does equal true (not true& or anything like that)

I'll try to adapt it if you have a case where it won't work :)

回答8:

public static string RemoveQueryStringByKey(string sURL, string sKey)
    {
        string sOutput = string.Empty;
        string sToReplace = string.Empty;

        int iFindTheKey = sURL.IndexOf(sKey);
        if (iFindTheKey == -1) return (sURL);

        int iQuestion = sURL.IndexOf('?');
        if (iQuestion == -1) return (sURL);

        string sEverythingBehindQ = sURL.Substring(iQuestion);
        List<string> everythingBehindQ = new List<string>(sEverythingBehindQ.Split('&'));
        foreach (string OneParamPair in everythingBehindQ)
        {
            int iIsKeyInThisParamPair = OneParamPair.IndexOf(sKey);
            if (iIsKeyInThisParamPair != -1)
            {
                sToReplace = "&" + OneParamPair;
            }
        }

        sOutput = sURL.Replace(sToReplace, "");
        return (sOutput);
    }

回答9:

Below code before deleting your QueryString.

 PropertyInfo isreadonly = 
          typeof(System.Collections.Specialized.NameValueCollection).GetProperty(
          "IsReadOnly", BindingFlags.Instance | BindingFlags.NonPublic);
        // make collection editable
        isreadonly.SetValue(this.Request.QueryString, false, null);
        // remove
        this.Request.QueryString.Remove("yourKey");

回答10:

Sorry this is a bit dirty but should work in older framework

public String RemoveQueryString( String rawUrl  , String keyName)
{
    var currentURL_Split =  rawUrl.Split('&').ToList();
    currentURL_Split = currentURL_Split.Where(o => !o.ToLower().StartsWith(keyName.ToLower()+"=")).ToList();
    String New_RemovedKey = String.Join("&", currentURL_Split.ToArray()); 
    New_RemovedKey = New_RemovedKey.Replace("&&", "&");
    return New_RemovedKey;
}

回答11:

Here is my solution:

I'v added some extra input validation.

public static void TryRemoveQueryStringByKey(ref string url, string key)
{
    if (string.IsNullOrEmpty(url) ||
        string.IsNullOrEmpty(key) ||
        Uri.IsWellFormedUriString(url, UriKind.RelativeOrAbsolute) == false)
    {
        return false;
    }            

    try
    {
        Uri uri = new Uri(url);

        // This gets all the query string key value pairs as a collection
        NameValueCollection queryCollection = HttpUtility.ParseQueryString(uri.Query);
        string keyValue = queryCollection.Get(key);

        if (url.IndexOf("&" + key + "=" + keyValue, StringComparison.OrdinalIgnoreCase) >= 0)
        {
            url = url.Replace("&" + key + "=" + keyValue, String.Empty);
            return true;
        }
        else if (url.IndexOf("?" + key + "=" + keyValue, StringComparison.OrdinalIgnoreCase) >= 0)
        {
            url = url.Replace("?" + key + "=" + keyValue, String.Empty);
            return true;
        }
        else
        {
            return false;
        }
    }
    catch
    {
        return false;
    }
}

Some unit testing examples:

string url1 = "http://www.gmail.com?a=1&cookie=cookieValue"
Assert.IsTrue(TryRemoveQueryStringByKey(ref url1,"cookie")); //OUTPUT: "http://www.gmail.com?a=1"

string url2 = "http://www.gmail.com?cookie=cookieValue"  
Assert.IsTrue(TryRemoveQueryStringByKey(ref url2,"cookie")); //OUTPUT: "http://www.gmail.com"

string url3 = "http://www.gmail.com?cookie="  
Assert.IsTrue(TryRemoveQueryStringByKey(ref url2,"cookie")); //OUTPUT: "http://www.gmail.com"

回答12:

Here's a full solution that works with >= 0 params specified, and any form of URL:

    /// <summary>
    /// Given a URL in any format, return URL with specified query string param removed if it exists
    /// </summary>
    public static string StripQueryStringParam(string url, string paramToRemove)
    {
        return StripQueryStringParams(url, new List<string> {paramToRemove});
    }

    /// <summary>
    /// Given a URL in any format, return URL with specified query string params removed if it exists
    /// </summary>
    public static string StripQueryStringParams(string url, List<string> paramsToRemove)
    {
        if (paramsToRemove == null || !paramsToRemove.Any()) return url;

        var splitUrl = url.Split('?');
        if (splitUrl.Length == 1) return url;

        var urlFirstPart = splitUrl[0];
        var urlSecondPart = splitUrl[1];

        // Even though in most cases # isn't available to context,
        // we may be passing it in explicitly for helper urls
        var secondPartSplit = urlSecondPart.Split('#');
        var querystring = secondPartSplit[0];
        var hashUrlPart = string.Empty;
        if (secondPartSplit.Length > 1)
        {
            hashUrlPart = "#" + secondPartSplit[1];
        }
        var nvc = HttpUtility.ParseQueryString(querystring);
        if (!nvc.HasKeys()) return url;

        // Remove any matches
        foreach (var key in nvc.AllKeys)
        {
            if (paramsToRemove.Contains(key))
            {
                nvc.Remove(key);
            }
        }

        if (!nvc.HasKeys()) return urlFirstPart;
        return urlFirstPart + 
               "?" + string.Join("&", nvc.AllKeys.Select(c => c.ToString() + "=" + nvc[c.ToString()])) + 
               hashUrlPart;
    }

回答13:

string url = HttpContext.Current.Request.Url.AbsoluteUri;
string[] separateURL = url.Split('?');

NameValueCollection queryString = System.Web.HttpUtility.ParseQueryString(separateURL[1]);
queryString.Remove("param_toremove");

string revisedurl = separateURL[0] + "?" + queryString.ToString();