title: Typeorm - Cannot update entity because entity id is not set in the entity
body: <p>I'm trying to save (insert) a new record in my DB but all i get is the error: <code>Cannot update entity because entity id is not set in the entity.</code></p>
  <p>What I'm currently doing:</p>
  <pre class="lang-js prettyprint-override"><code>return this.connection.transaction(entityManager =&gt; {
     return entityManager.save(MyEntity, {/* payload without id */});
  });
  
  </code></pre>
  <p>This is the only place in my codebase where this issue happen (transaction or not)</p>