Pass System.Uri objects instead of strings
Collapse the table of content
Expand the table of content
Important This document may not represent best practices for current development, links to downloads and other resources may no longer be valid. Current recommended version can be found here. ArchiveDisclaimer

Pass System.Uri objects instead of strings







Breaking Change

Non Breaking

A call is made to a method that has a string parameter whose name contains "uri", "Uri", "urn", "Urn", "url", or "Url"; and the declaring type of the method contains a corresponding method overload that has a System.Uri parameter.

A parameter name is split into tokens based on the camel casing convention, and then each token is checked to see whether it equals "uri", "Uri", "urn", "Urn", "url", or "Url". If there is a match, the parameter is assumed to represent a uniform resource identifier (URI). A string representation of a URI is prone to parsing and encoding errors, and can lead to security vulnerabilities. The Uri class provides these services in a safe and secure manner. When there is a choice between two overloads that differ only regarding the representation of a URI, the user should choose the overload that takes a Uri argument.

To fix a violation of this rule, call the overload that takes the Uri argument.

It is safe to suppress a warning from this rule if the string parameter does not represent a URI.

The following example shows a method, ErrorProne, which violates the rule and a method, SaferWay, which correctly calls the Uri overload.

using System;

namespace DesignLibrary
   class History
      internal void AddToHistory(string uriString) {}
      internal void AddToHistory(Uri uriType) {}

   public class Browser
      History uriHistory = new History();

      public void ErrorProne()

      public void SaferWay()
            Uri newUri = new Uri("");
         catch(UriFormatException uriException) {}
© 2015 Microsoft