title: How do I write EF.Functions extension method?
body: <p>I see that EF Core 2 has EF.Functions property <a href="https://blogs.msdn.microsoft.com/dotnet/2017/05/12/announcing-ef-core-2-0-preview-1/" rel="noreferrer">EF Core 2.0 Announcement</a> <code>which can be used by EF Core or providers to define methods that map to database functions or operators so that those can be invoked in LINQ queries</code>. It included LIKE method that gets sent to the database.</p>
  
  <p>But I need a different method, SOUNDEX() that is <em>not</em> included. How do I write such a method that passes the function to the database the way <code>DbFunction</code> attribute did in EF6? Or I need to wait for MS to implement it? Essentially, I need to generate something like</p>
  
  <pre><code>SELECT * FROM Customer WHERE SOUNDEX(lastname) = SOUNDEX(@param)
  </code></pre>