title: How to handle async when making mongoose query in each array element in express?
body: <p>On the following post method, I'm having some issues due to moongose async. <code>res.send(suggestions)</code> is executed first then <code>Expense.findOne.exec</code></p>
  
  <pre><code>app.post('/suggestions', async function(req, res) {
      const suggestions = await req.body.map((description) =&gt; {
          Expense.findOne({ description: new RegExp(description, 'i') }).exec((err, result) =&gt; {
              if (result) {
                  console.log(result.newDescription);
                  return {
                      description,
                      newDescription: result.newDescription,
                      category: result.category,
                      subcategory: result.subcategory
                  };
              }
          });
      });
  
      res.send(suggestions);
  });
  
  </code></pre>
  
  <p>The result is a array of null values. How can I executed a query for each item, then execute <code>res.send(suggestion)</code>?</p>