title: MongoDB Update Array with C# Driver
body: <p>Using MongoDB, How do I update a single array element within a document using the C# Driver.</p>
  
  <p>Allow me to setup this up. Assume there is a collection, called "Things".  Within the Things collection, there are many document. Here are two "things" documents:</p>
  
  <pre><code>{
      "_id":"2d7fcf21-34b8-4537-b07f-01659d87eda4",
      "Name":"Something",
      "Stuff":[
          {
              "Id":"1fdd098c-5e60-4dd8-a6a6-96b26cd90dc9",
              "Completed":false
          },
          {
              "Id":"b63cc911-a577-4744-bb0f-b9d9deabcf66",
              "Completed":false
          }
      ]
  }
  
  
  {
      "_id":"d4ba4420-238f-4e11-9ad8-721dc3eb0ad7
      ",
      "Name":"Another Thing",
      "Stuff":[
          {
              "Id":"f2d46144-15eb-4451-851a-cba80dd8949b",
              "Completed":false
          },
          {
              "Id":"f2d46144-15eb-4451-851a-cba80dd8949b",
              "Completed":false
          }
      ]
  }
  </code></pre>
  
  <p>If I have the _id of the document, and Id of the the item in the array I want to change, how can I toggle the "Completed" property from false to true, without replacing the entire document or array?</p>
  
  <p>The data I am showing here is not actual data from the application I'm working on, it is contrived for this example.  Also, I am using the C# MongoDB Driver v2.7.2 and my database is running on MongoDB v4 on Atlas.</p>