Summary  
Demonstrates how to replace in-memory data with asynchronous database queries in GET endpoints by using model methods to fetch all records or a single record by ID.

General domain of usage  
Web API development


So far, data may have been stored in arrays or temporary variables. Now you replace that logic with database queries.

Instead of returning hardcoded data, you use the model to fetch data from MongoDB.

```javascript id="9t2kqp"
app.get('/users', async (req, res) => {
  const users = await User.find();

  res.json(users);
});
```

For a single item:

```javascript id="k3m8ax"
app.get('/users/:id', async (req, res) => {
  const user = await User.findById(req.params.id);

  res.json(user);
});
```

Examples:

* `'/users'`: returns all users from database;
* `'/users/123'`: returns user with id 123 from database.

This replaces in-memory data with real database data.



What changes when connecting your API to a database?

Learn how to store and manage data in backend applications using MongoDB and Mongoose. Connect your Express API to a database and perform create, read, update, and delete operations. Build real data-driven backend functionality and move beyond in-memory storage.

Connecting Database to Existing API (GET)