Replace host in Uri

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Problem :

What is the nicest way of replacing the host-part of an Uri using .NET?


string ReplaceHost(string original, string newHostName);
string s = ReplaceHost("http://oldhostname/index.html", "newhostname");
Assert.AreEqual("http://newhostname/index.html", s);
string s = ReplaceHost("http://user:pass@oldhostname/index.html", "newhostname");
Assert.AreEqual("http://user:pass@newhostname/index.html", s);
string s = ReplaceHost("ftp://user:pass@oldhostname", "newhostname");
Assert.AreEqual("ftp://user:pass@newhostname", s);

System.Uri does not seem to help much.

Solution :

System.UriBuilder is what you are after…

string ReplaceHost(string original, string newHostName) {
    var builder = new UriBuilder(original);
    builder.Host = newHostName;
    return builder.Uri.ToString();

As @Ishmael says, you can use System.UriBuilder. Here’s an example:

// the URI for which you want to change the host name
var oldUri = Request.Url;

// create a new UriBuilder, which copies all fragments of the source URI
var newUriBuilder = new UriBuilder(oldUri);

// set the new host (you can set other properties too)
newUriBuilder.Host = "";

// get a Uri instance from the UriBuilder
var newUri = newUriBuilder.Uri;

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