title: How to make the "join" of an array of objects ids with MongoDB
body: <p>I'm facing some dificult to make this query with the MongoDB Aggregation Framrwork.</p>
  
  <p>I have a order collection that has an array of objects ids from products example:</p>
  
  <pre><code>{
    _id: "5759b760aeacbfa420943d84",
    products: [
      "57718a2c9473f30ae88d1875",
      "57727d988d7e581809b454a1",
      "577bda7da756e2180507a944"
    ]
  }
  </code></pre>
  
  <p>Here is an example of one document from my products ocllection:</p>
  
  <pre><code>{
    _id: "57718a2c9473f30ae88d1875",
    name: "Soap A"
  }
  </code></pre>
  
  <p>How can I make an aggregation query in orders to get a list of contained products documents?</p>