Get Absolute URL from Relative path refactored method

Question

I am really surprised that there is no native  NET method to get an absolute url from a relative url  I know this has been discussed many times  but never have come across a satisfactory method that handles this well  Can you help fine tune the method below   I think all I need left is to auto choose the protocol instead of hard coding it  http https   Anything else I am missing  caveats  performance  etc    public static string GetAbsoluteUrl string url                  VALIDATE INPUT FOR ALREADY ABSOLUTE URL         if  url StartsWith  http      StringComparison OrdinalIgnoreCase                 url StartsWith  https      StringComparison OrdinalIgnoreCase                          return url                       GET PAGE REFERENCE FOR CONTEXT PROCESSING         Page page   HttpContext Current Handler as Page             RESOLVE PATH FOR APPLICATION BEFORE PROCESSING         if  url StartsWith                              url   page ResolveUrl url                        BUILD AND RETURN ABSOLUTE URL         return  http       page Request ServerVariables  SERVER NAME                                     url TrimStart

User · Answer

This one works for me     new System Uri Page Request Url  ResolveClientUrl    mypage aspx    AbsoluteUri

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This has always been my approach to this little nuisance  Note the use of VirtualPathUtility ToAbsolute relativeUrl  allows the method to be declared as an extension in a static class        lt summary gt      Converts the provided app-relative path into an absolute Url containing the      full host name      lt  summary gt       lt param name  relativeUrl  gt App-Relative path lt  param gt       lt returns gt Provided relativeUrl parameter as fully qualified Url lt  returns gt       lt example gt   path to foo to http   www web com path to foo lt  example gt  public static string ToAbsoluteUrl this string relativeUrl        if  string IsNullOrEmpty relativeUrl           return relativeUrl       if  HttpContext Current    null          return relativeUrl       if  relativeUrl StartsWith               relativeUrl   relativeUrl Insert 0            if   relativeUrl StartsWith                relativeUrl   relativeUrl Insert 0              var url   HttpContext Current Request Url      var port   url Port    80          url Port    String Empty       return String Format   0     1  2  3            url Scheme  url Host  port  VirtualPathUtility ToAbsolute relativeUrl

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With ASP NET  you need to consider the reference point for a  relative URL  - is it relative to the page request  a user control  or if it is  relative  simply by virtue of using        The Uri class contains a simple way to convert a relative URL to an absolute URL  given an absolute URL as the reference point for the relative URL    var uri   new Uri absoluteUrl  relativeUrl     If relativeUrl is in fact an abolute URL  then the absoluteUrl is ignored   The only question then remains what the reference point is  and whether      URLs are allowed  the Uri constructor does not translate these

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Still nothing good enough using native stuff  Here is what I ended up with   public static string GetAbsoluteUrl string url          VALIDATE INPUT     if  String IsNullOrEmpty url                 return String Empty               VALIDATE INPUT FOR ALREADY ABSOLUTE URL     if  url StartsWith  http      StringComparison OrdinalIgnoreCase     url StartsWith  https      StringComparison OrdinalIgnoreCase                  return url               GET CONTEXT OF CURRENT USER     HttpContext context   HttpContext Current         RESOLVE PATH FOR APPLICATION BEFORE PROCESSING     if  url StartsWith                      url    context Handler as Page  ResolveUrl url                BUILD AND RETURN ABSOLUTE URL     string port    context Request Url Port    80  amp  amp  context Request Url Port    443          context Request Url Port   String Empty      return context Request Url Scheme   Uri SchemeDelimiter   context Request Url Host   port         url TrimStart

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If you re in the context of an MVC Controller or View you can use the UrlHelper which should be accessible via just Url  Url Content    content images myimage jpg     Which will be fully expanded to  virtual directoryname content images myimage jpg  This can be used in a controller or  cshtml file  Yes it is a little odd that it s called Content but it s meant to be used to get an absolute path to a resource so it makes sense

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This works fine too   HttpContext Current Server MapPath relativePath    Where relative path is something like    foo file jpg

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check the following code to retrieve absolute Url    Page Request Url AbsoluteUri   I hope to be useful

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The final version taking care of all previous complaints  ports  logical url  relative url  existing absolute url   etc   considering the current handler is the page   public static string ConvertToAbsoluteUrl string url        if   IsAbsoluteUrl url                 if  HttpContext Current    null  amp  amp  HttpContext Current Request    null  amp  amp  HttpContext Current Handler is System Web UI Page                        var originalUrl   HttpContext Current Request Url              return string Format   0     1  2  3    originalUrl Scheme  originalUrl Host   originalUrl IsDefaultPort          originalUrl Port    string Empty    System Web UI Page HttpContext Current Handler  ResolveUrl url                      throw new Exception  Invalid context               else         return url     private static bool IsAbsoluteUrl string url        Uri result      return Uri TryCreate url  UriKind Absolute  out result

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Here is my own version that handles many validations and relative pathing from user s current location option  Feel free to refactor from here          lt summary gt      Converts the provided app-relative path into an absolute Url containing      the full host name      lt  summary gt       lt param name  relativeUrl  gt App-Relative path lt  param gt       lt returns gt Provided relativeUrl parameter as fully qualified Url lt  returns gt       lt example gt   path to foo to http   www web com path to foo lt  example gt  public static string GetAbsoluteUrl string relativeUrl          VALIDATE INPUT     if  String IsNullOrEmpty relativeUrl           return String Empty        VALIDATE INPUT FOR ALREADY ABSOLUTE URL     if  relativeUrl StartsWith  http      StringComparison OrdinalIgnoreCase          relativeUrl StartsWith  https      StringComparison OrdinalIgnoreCase           return relativeUrl        VALIDATE CONTEXT     if  HttpContext Current    null          return relativeUrl        GET CONTEXT OF CURRENT USER     HttpContext context   HttpContext Current        FIX ROOT PATH TO APP ROOT PATH     if  relativeUrl StartsWith               relativeUrl   relativeUrl Insert 0              GET RELATIVE PATH     Page page   context Handler as Page      if  page    null                  USE PAGE IN CASE RELATIVE TO USER S CURRENT LOCATION IS NEEDED         relativeUrl   page ResolveUrl relativeUrl             else   OTHERWISE ASSUME WE WANT ROOT PATH                PREPARE TO USE IN VIRTUAL PATH UTILITY         if   relativeUrl StartsWith                    relativeUrl   relativeUrl Insert 0                 relativeUrl   VirtualPathUtility ToAbsolute relativeUrl              var url   context Request Url      var port   url Port    80          url Port    String Empty        BUILD AND RETURN ABSOLUTE URL     return String Format   0     1  2  3               url Scheme  url Host  port  relativeUrl

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When you want to generate URL from your Business Logic layer  you do not have the flexibility of using ASP NET Web Form s Page class  Control s ResolveUrl     etc  Moreover  you may need to generate URL from ASP NET MVC controller too where you not only miss the Web Form s ResolveUrl     method  but also you cannot get the Url Action     even though Url Action takes only Controller name and Action name  not the relative url    I tried using      var uri   new Uri absoluteUrl  relativeUrl    approach  but there is a problem too  If the web application is hosted in IIS virtual directory  where the url of the app is like this   http   localhost MyWebApplication1   and the relative url is   myPage  then the relative url is resolved as  http   localhost MyPage  which is another problem   Therefore  in order to overcome such problems  I have written a UrlUtils class which can work from a class library  So  it wont depend on Page class but it depends on ASP NET MVC  So  if you dont mind adding reference to MVC dll to your class library project then my class will work smoothly  I have tested in IIS virtual directory scenario where the web application url is like this   http   localhost MyWebApplication MyPage  I realized that  sometimes we need to make sure that the Absolute url is SSL url or non SSL url  So  I wrote my class library supporting this option  I have restricted this class library so that the relative url can be absolute url or a relative url that starts with         Using this library  I can call  string absoluteUrl   UrlUtils MapUrl    Contact      Returns   http   localhost Contact   when the page url is   http   localhost Home About  Returns   http   localhost MyWebApplication Contact   when the page url is   http   localhost MyWebApplication Home About    string absoluteUrl   UrlUtils MapUrl    Contact   UrlUtils UrlMapOptions AlwaysSSL     Returns     https     localhost MyWebApplication Contact   when the page url is   http   localhost MyWebApplication Home About  Here is my class Library     public class UrlUtils               public enum UrlMapOptions                       AlwaysNonSSL              AlwaysSSL              BasedOnCurrentScheme                    public static string MapUrl string relativeUrl  UrlMapOptions option   UrlMapOptions BasedOnCurrentScheme                        if  relativeUrl StartsWith  http      StringComparison OrdinalIgnoreCase                     relativeUrl StartsWith  https      StringComparison OrdinalIgnoreCase                   return relativeUrl               if   relativeUrl StartsWith                        throw new Exception  The relative url must start with                    UrlHelper theHelper   new UrlHelper HttpContext Current Request RequestContext                string theAbsoluteUrl   HttpContext Current Request Url GetLeftPart UriPartial Authority                                               theHelper Content relativeUrl                switch  option                                case UrlMapOptions AlwaysNonSSL                                                return theAbsoluteUrl StartsWith  https      StringComparison OrdinalIgnoreCase                                string Format  http    0    theAbsoluteUrl Remove 0  8                                 theAbsoluteUrl                                        case UrlMapOptions AlwaysSSL                                                return theAbsoluteUrl StartsWith  https      StringComparison OrdinalIgnoreCase                                theAbsoluteUrl                               string Format  https    0    theAbsoluteUrl Remove 0  7                                                     return theAbsoluteUrl

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new System Uri Page Request Url    myRelativeUrl aspx   AbsoluteUri

[c#] Get Absolute URL from Relative path (refactored method)

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