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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 exclude 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.

Imports System

Namespace DesignLibrary

   Public Class ErrorProne
   
      Dim someUriValue As String 

      ' Violates rule UriPropertiesShouldNotBeStrings.
      Property SomeUri As String
         Get 
            Return someUriValue 
         End Get
         Set 
            someUriValue = Value 
         End Set
      End Property

      ' Violates rule UriParametersShouldNotBeStrings.
      Sub AddToHistory(uriString As String)
      End Sub

      ' Violates rule UriReturnValuesShouldNotBeStrings.
      Function GetRefererUri(httpHeader As String) As String
         Return "http://www.adventure-works.com"
      End Function

   End Class

   Public Class SaferWay
   
      Dim someUriValue As Uri 

      ' To retrieve a string, call SomeUri.ToString().
      ' To set using a string, call SomeUri = New Uri(string).
      Property SomeUri As Uri
         Get 
            Return someUriValue 
         End Get
         Set 
            someUriValue = Value 
         End Set
      End Property

      Sub AddToHistory(uriString As String)
         ' Check for UriFormatException.
         AddToHistory(New Uri(uriString))
      End Sub

      Sub AddToHistory(uriString As Uri)
      End Sub

      Function GetRefererUri(httpHeader As String) As Uri
         Return New Uri("http://www.adventure-works.com")
      End Function

   End Class

End Namespace

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