title: Proper way to two .save() in mongoose
body: <p>I am trying to save to two different docs and two different models in the same function, but no matter what I try I seem to get weird errors. It seems like for whatever reason mongoose has made this exclusively not work.</p>
  <p>I have two findOne functions nested one is finding the book while the other is finding the prof and the object is to update them both to relate to each other.</p>
  <p>Is there a recommended way I should do this perhaps two seperate backend endpoints and two seperate functions? that would be one solution to this problem, but I'd like to know why I cannot do whats below.</p>
  <pre><code>await prof.save().then(async () =&gt; {
        await book
              .save()
              .then(() =&gt; {
                  return res.status(200).json({
                     success: true,
                     message: 'items updated'
               }).catch( (err) =&gt; {
                   return res.status(400)
               })
        })
  })
  </code></pre>