title: Check which elements are on one list comparing to another list LINQ
body: <p>I have two lists, one of all languages and another subset of languages that the site has, the idea is to return all the languages but change the property of a boolean if the element of the subset corresponds to the list of all languages.</p>
  
  <p><strong>DTO of language:</strong></p>
  
  <pre><code>public class DTOLanguage
  {
  
      public bool HaveLanguage { get; set; }
      public int IdLanguage { get; set; }
      //Other properties...
  }
  </code></pre>
  
  <p><strong>Method that returns all languages:</strong></p>
  
  <pre><code>public List&lt;DTOLanguage&gt; GetLanguages()
  {
      var result = repository.RepSite.GetLanguages().Select(x =&gt; new DTOLanguage
      {
          IdLanguage = x.IdLanguage,
          CodName = x.CodName,
          Name = x.Name
      }).ToList();
  
      return result;
  }
  </code></pre>
  
  <p><strong>Method that returns the subset of languages:</strong></p>
  
  <pre><code>public List&lt;DTOLanguage&gt; GetLanguagesById(int idSite)
  {
      var result = repository.RepSite.GetLanguagesById(idSite).Select(x =&gt; new DTOLanguage
      {
          IdLanguage = x.IdLanguage
      }).ToList();
  
      return result;
  }
  </code></pre>
  
  <p>The <code>GetLanguagesById</code> is called in the DataAccess layer, so what Im thinking is that this method should receive another parameter (what <code>GetLanguages</code> returns) and make some fancy LINQ there.</p>
  
  <p>I know that I can filter (example):</p>
  
  <pre><code>SubsetOfLanguages.Where(lg =&gt; lg.IdLanguage == AllLanguagesItem.IdLanguage)
      {
          AllLanguagesItem.HaveLanguage = True;
      }
  </code></pre>
  
  <p>But Im not really sure as how it should be.</p>
  
  <p>Thanks in advance.</p>