connect to mongo once

connect.js

 await mongoose.connect(dbUrl, {
    useNewUrlParser: true,
    useUnifiedTopology: true,
    useCreateIndex: true,
    useFindAndModify: false,
  });
  
  const connection = mongoose.connection;
  
  connection.once("open", function() {
    console.log("MongoDB database connection established successfully");
  });