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URI return values should not be strings

TypeName

UriReturnValuesShouldNotBeStrings

CheckId

CA1055

Category

Microsoft.Design

Breaking Change

Breaking

The name of a method contains "uri", "Uri", "urn", "Urn", "url", or "Url", and the method returns a string.

This rule splits the method name into tokens based on the Pascal casing convention and checks whether each token equals "uri", "Uri", "urn", "Urn", "url", or "Url". If there is a match, the rule assumes that the method returns 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 System.Uri class provides these services in a safe and secure manner.

To fix a violation of this rule, change the return type to a Uri.

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

The following example shows a type, ErrorProne, that violates this rule, and a type, SaferWay, that satisfies the rule.

using System;

namespace DesignLibrary
{
   public class ErrorProne
   {
      string someUri;

      // Violates rule UriPropertiesShouldNotBeStrings. 
      public string SomeUri
      {
         get { return someUri; }
         set { someUri = value; }
      }

      // Violates rule UriParametersShouldNotBeStrings. 
      public void AddToHistory(string uriString) { }

      // Violates rule UriReturnValuesShouldNotBeStrings. 
      public string GetRefererUri(string httpHeader)
      {
         return "http://www.adventure-works.com";
      }
   }

   public class SaferWay
   {
      Uri someUri;

      // To retrieve a string, call SomeUri.ToString(). 
      // To set using a string, call SomeUri = new Uri(string). 
      public Uri SomeUri
      {
         get { return someUri; }
         set { someUri = value; }
      }

      public void AddToHistory(string uriString)
      {
         // Check for UriFormatException.
         AddToHistory(new Uri(uriString));
      }

      public void AddToHistory(Uri uriType) { }

      public Uri GetRefererUri(string httpHeader)
      {
         return new Uri("http://www.adventure-works.com");
      }
   }
}

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