Why Get A Relative Path From One To Another Working Not Correct?

Question

guys i tried this one:

current: \netcoreapp2.1\ResultPath

target : \netcoreapp2.1\ReportPath\report1

   AssemblyDirectory = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);

   Uri currentPath = new Uri(AssemblyDirectory + "//ResultPath");
   Uri targetPath = new Uri(reportsSubDir);

   Uri relPath = currentPath.MakeRelativeUri(targetPath);

In result i'm getting

relPath.OriginalString = ReportPath/report1

Why is not ../ReportPath/report1 ?

And now for example:

if i have

current: \netcoreapp2.1\ResultPath\Test

target : \netcoreapp2.1\ReportPath\report1

I'm getting correct result in this way

relPath.OriginalString = ../../ReportPath/report10

Could anyone explain me why in first step i'm getting bad Relative Path, but in second good

and any idea how can i fix it, if i want to use first and second examples in my way ?

Answer 1

Well, if you are using .NET 5, you're in luck, since new method was included: Path.GetRelativePath(string, string)

If not, we can always dig into MS .NET Framework code:

https://referencesource.microsoft.com/#System.Workflow.ComponentModel/AuthoringOM/Design/DesignerHelpers.cs,a561eb779ce7163d

And copy implementation, which is:

static class PathHelper
 {
     internal static string GetRelativePath(string pathFrom, string pathTo)
     {
         Uri uri = new Uri(pathFrom);
         string relativePath = Uri.UnescapeDataString(uri.MakeRelativeUri(new Uri(pathTo)).ToString());
         relativePath = relativePath.Replace(Path.AltDirectorySeparatorChar, Path.DirectorySeparatorChar);
         if (!relativePath.Contains(Path.DirectorySeparatorChar.ToString()))
             relativePath = "." + Path.DirectorySeparatorChar + relativePath;
         return relativePath;
     }
 }

Usage then would be:

var p1 = @"C:\users\turek\source\";
var p2 = @"C:\users\turek\desktop\";

PathHelper.GetRelativePath(p1, p2);
// returns "..\\desktop\\"