const mongodb = require("mongodb");

run().catch(error => console.error(error));

async function run() {
  console.log(new Date(), "Connecting to localhost");
  const uri = "mongodb://127.0.0.1:27017/test?replicaSet=repl0";
  const client = await mongodb.MongoClient.connect(
    uri,
    function(err, client) {
      if (err) throw err;
      const db = client.db("IoTData");
      const Filter = [
        {
          $match: {
            operationType: { $in: ["insert"] },
            "fullDocument.cameraImage": { $exists: true }
          }
        }
      ];

      console.log(new Date(), "Watching for changes...");
      db.collection("SecurityApp")
        .watch(Filter)
        .on("change", data => {
          console.log(new Date(), "Camera Image Attached to Document!");
        });
    }
  );
}
/*  Make sure you are using at least MongoDB NodeJS Driver 3.0 and above
{
    "name": "detectnewfield",
    "version": "1.0.0",
    "description": "Detects New Field",
    "main": "DetectHighTemp.js",
    "scripts": {
      "debug": "node DetectNewField.js"
    },
    "author": "Rob Walters",
    "license": "MIT",
    "dependencies": {
      "mongodb": "^3.1.0"
    }
  }*/