title: Mongoose find in object array value
body: <p>Example of Article object array:</p>
  
  <pre><code>[
      {
          "_id": "72",
          "title": "Some title",
          "comments": [
              {
                  "title": "title 1",
                  "_id": "0",
              },
              {
                  "title": "title 2",
                  "_id": "1",
              },
              {
                  "title": "title 3",
                  "_id": "2",
              }
          ]
      },
      (...)
  ]
  </code></pre>
  
  <p>I would like to find some articles by their comments title (populated)</p>
  
  <pre><code>var ArticleSchema = new Schema({
      title: { type: String },
      comments: [{ type: Schema.ObjectId, ref: 'Comment' }]
  });
  </code></pre>
  
  <p>I tried a lot of things like:</p>
  
  <pre><code>var options = {
      criteria: {
          'comments.title': regex
      }
  };
  
  Article
      .find(options.criteria, function (err, articles) {
          if (err) throw err;
          res.json(articles);
      })
      .populate('comments');
  </code></pre>
  
  <p>but does not work...</p>
  
  <p>Thanks</p>
  
  <ul>
  <li>Update *</li>
  </ul>
  
  <p>Here my new code: three nested find() and two forEach() </p>