title: Appending multiple bool filters to a NEST query
body: <p>I'd like to append multiple bool filters with NEST, but I can't (practically) do it in a single statement as I want to build a set of <strong>Bool</strong> filters depending on different conditions.</p>
  
  <p>Something like this pseudo code:</p>
  
  <pre class="lang-cs prettyprint-override"><code>// Append a filter
  searchDescriptor.Filter(f =&gt; f.Bool(b =&gt; b.Must(m =&gt; m.Term(i =&gt; i.SomeProperty, "SomeValue"))));
  
  if (UserId.HasValue)
  {
     // Optionally append another filter (AND condition with the first filter)
     searchDescriptor.Filter(f =&gt; f.Bool(b =&gt; b.Must(m =&gt; m.Term(i =&gt; i.AnotherProperty, "MyOtherValue"))));
  }
  
  var result = Client.Search(searchDescriptor);
  </code></pre>
  
  <p>Now it seems when the second optional filter is appended, it essentially replaces the first filter.</p>
  
  <p>I'm sure I'm missing something syntactically, but I can't figure it out and the NEST documentation is a bit thin on the filter DSL. :)</p>