title: Ignore properties set undefined on GET request in Angular with Typescript
body: <p>I'm trying to request some data from the server. When I change a property's model to undefined this "undefined" string is sent in the query string.</p>
  
  <pre><code>let filterModel = new GroupFilterModel();
  filterModel.status = anycondition ? "opened" : undefined;
  this.http.get&lt;GroupModel[]&gt;("apiurl", { params: filterModel });
  </code></pre>
  
  <p>The querystring sent is something like this:</p>
  
  <pre><code>apiurl?status=undefined
  </code></pre>
  
  <p>I want to avoid sending the status variable. How can I have this behaviour?</p>