The last method we're going to look at is Todo.findById. Now, findById is fantastic if you are just looking for a document by its identifier. There is no way to query by anything else other than the ID and all you do is you pass in the id as the argument. You don't have to make a query object and you don't have to set an _id prompt. With this in place, we can now do the exact same thing we did with findOne. I'm going to prove that by taking the then call, pasting it inside Todo.findById, and just changing the print statement from Todo to Todo By Id:

Todo.findById(id).then((todo) => {
   console.log('Todo By Id', todo);
});

Now if I save the file, nodemon is going to rerun and we get the exact same result for both:

If you want to find one document by something other than ID, I recommend using findOne. If you want to find one document by ID, I always recommend using findById. Now, all of this and more is available in the docs, so if you want to dive into anything I discussed here you can always go to mongoosejs.com. Click on the read the docs link, and over in the left-hand side they have a couple of links; the one that we're looking for is the one on Queries:

You can learn more about how to query your docs, but we pretty much covered everything this page talks about.