title: "Class 'MongoDB\Driver\Manager' not found" in PHP
body: <p>I installed MongoDB library with Composer:</p>
  
  <pre><code>composer require jenssegers/mongodb
  </code></pre>
  
  <p>I got that error: "Class 'MongoDB\Driver\Manager' not found",</p>
  
  <p>I tried many things but problem is not solved,
  But finally I noticed that the class file is really not existing in library!
  I havent found it anyway...</p>
  
  <p>What am I missing?</p>
  
  <p>Where can I found full package for MongoDB in PHP?</p>
  
  <p><strong>Please be aware of that: similar questions are not mentioning lack of class file.</strong></p>