title: Custom validation attribute that compares the value of my property with another property's value in my model class
body: <p>I want to create a custom validation attribute, in which I want to compare the value of my property with another property's value in my model class.
  For example I have in my model class:</p>
  
  <pre><code>...    
  public string SourceCity { get; set; }
  public string DestinationCity { get; set; }
  </code></pre>
  
  <p>And I want to create a custom attribute to use it like this: </p>
  
  <pre><code>[Custom("SourceCity", ErrorMessage = "the source and destination should not be equal")]
  public string DestinationCity { get; set; }
  //this wil lcompare SourceCity with DestinationCity
  </code></pre>
  
  <p>How can I get there?</p>