Implementing our RESTDataSource

4. Implementing our RESTDataSource

Let's add this RESTDataSource class to our project.

In the terminal, in our server/ folder, stop the current process that we started in the project setup section, then run:

npm install @apollo/datasource-rest

Once that's done, start up the server again with npm start.

Next, let's create a folder called datasources in the server/src folder, where all our data sources will live. We'll create a file called track-api.js.

First, we import our @apollo/datasource-rest package.

const { RESTDataSource } = require("@apollo/datasource-rest");

This gives us a RESTDataSource class that we can extend.

We'll declare a class called TrackAPI that extends RESTDataSource. While we're here, let's export it before we forget!

class TrackAPI extends RESTDataSource {
  // ...
}
module.exports = TrackAPI;

Next, let's assign our REST API's baseURL. This property is used as the prefix to all the calls.

class TrackAPI extends RESTDataSource {
  baseURL = "https://odyssey-lift-off-rest-api.herokuapp.com/";
}

Note: Be sure that your TrackAPI class' baseURL value ends with a /. This will allow our helper class to make requests and append new paths to the baseURL without any errors.

Code Challenge!

Create a class called SpaceCatsAPI that extends the RESTDataSource class. Its baseURL should be set to https://fake-spacecats-rest-api.cat/. Assume that the RESTDataSource class has already been imported.

Let's define a method called getTracksForHome inside our TrackAPI class. The RESTDataSource class provides helper methods for HTTP requests. In our case, we want to perform a GET request to the tracks endpoint. Then, we return the results of that call.

getTracksForHome() {
  return this.get('tracks');
}

Next, it's time to define the getAuthor method inside our TrackAPI class. It takes an authorId as an argument and uses it in a GET call to the /author/:id endpoint. Then, we return the results of that call.

Below our getTracksForHome method:

getAuthor(authorId) {
  return this.get(`author/${authorId}`);
}

Note the use of backticks (`) enclosing the author/:id endpoint, because we're using string interpolation to add the authorId at the end.

Nice work! We've got our data source set up and retrieving data from the REST API.

server/src/datasources/track-api.js

const { RESTDataSource } = require("@apollo/datasource-rest");
 
class TrackAPI extends RESTDataSource {
  baseURL = "https://odyssey-lift-off-rest-api.herokuapp.com/";
   
  getTracksForHome() {
    return this.get("tracks");
  }
   
  getAuthor(authorId) {
    return this.get(`author/${authorId}`);
  }
}
 
module.exports = TrackAPI;

Code Challenge!

The SpaceCatsAPI class needs two methods. The first method is called getSpaceCats. This method makes a GET request to the spacecats endpoint and returns the results. The second method is called getMissions. It takes in a catId as an argument and makes a GET request to the spacecats/${catId}/missions endpoint and returns the results. Assume that the RESTDataSource class has already been imported.

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