How to query MongoDB using aysnc/await? - node.js

Question

So I'm following a course on Udemy to learn web development using Node/Express/MongoDB and using mongoose to interact with the database.
I have reached a lecture where the instructor started explaining on how to query the database so here created a mongoose model and named it Tour and in a controller file he wrote this to query the data that we already imported like this:
exports.getAllTours = async (req, res) => {
try {
const queryObj = { ...req.query };
const exludedFields = ["sort", "limit", "page", "fields"];
exludedFields.forEach(el => delete queryObj[el]);
const query = Tour.find(queryObj);
const tours = await query
res.status(200).json({
status: 'success',
data: {
tours: tours
}
})
} catch (err) {
res.status(404).json({
status: 'fail',
message: err.message
});
}
}
As you can see from the code above we used the handler function getAllTours to get all the tours which by the way it handles this route app.get('/api/v1/tours/').
At the beginning of the lecture the code for the query was like this: const query = await Tour.find(queryObj); and then he removed the await keyword to look like the code above were he included the await keyword for the tours object later.
The instructor explained this by saying that if we used the await on the query like this const query = await Tour.find(queryObj); then the code will execute immediately and then we would not be able to chain other methods on the query like .where() or .equals().
I need someone to explain these questions for me:
why would the code execute immediately if we used await?
the Tour.find() does need time to query the database, so I think we should add await, shouldn't we?

Answer 1

The Tour.find() returns a promise (is an async call), adding the await in front of it will wait until the promise is resolved and return it results.
If you want to do a where() after you do the find you can do it after the query is executed since you will have the results in that object in your case the tours object.
Honestly I prefer doing const tours = await Tour.find() you save a varaible that is kinda of innecesary, just is necesary if you want to catch an error of the promise or something like that.
In your case you using a try catch so the error will go to the catch block if something happens with the query (connection issues or other problems)