CRUD 101

Learning Objectives

• Define the acronym CRUD
• Process a GET request using Express and Node to retrieve data from memory
• Process a POST request using Express and Node and store data in memory
• Process a DELETE request using Express and Node to remove data from memory

Requirements

Today we will build a CRUD API. CRUD stands for Create, Retrieve,* U*pdate, Delete. If you think about it, this is what most applications do:

Create some “resources” Retrieve them (GET them) Update them Delete them

🎯 Workshop Objective

Our API will manage Beyoncé albums. It will:

Create a new album, Retrieve a list of albums or a single album, Update an existing album’s information Delete an album

We will build these endpoints:

1. GET /albums should return all the albums
2. GET /albums/:albumId should return a single album (that matches the passed albumId)
3. POST /albums should save a new album
4. DELETE /albums/:albumId should delete the album (that matches the passed albumId)

1. GET /albums should return all the albums

In server.js, create a GET /albums endpoint that returns all the albums. Some albums have been provided for you in albums.json.

app.get("/albums", (req, res) => {
  res.send(albumsData);
});

🧪 Run and test

1. npm run dev
2. Open Postman
3. Make a GET request to http://localhost:3000/albums

2. GET /albums/:albumId should return a single album (that matches the passed albumId)

Sometimes, we do not want to list all the information in one request, maybe we only want to get the information related to a single album. Imagine if we have a page to display the details of one album. We could call the server and get all albums then filter the one we need client-side. It would be more effective to tell the server to just return the one album we are interested in.

We will now add a new endpoint to return only a single album GET /albums/:albumId. In this case, albumId will tell us what album we can return. The call will be GET /albums/10 and that will return the album with that has albumId: "10".

This endpoint has something different. The endpoint /albums/:albumId has a dynamic part. The albumId will vary depending on what the client sends.

In server.js, create a GET /albums/:albumId endpoint that returns a single album. The albumId will be passed as a parameter in the URL.

app.get("/albums/:albumId", (req, res) => {
  const albumId = req.params.albumId;
 // now find the given album from the `albumsData` using the `albumId`
 // finally send the album you found back to the client
});

🧪 Run and test

1. Save your changes
2. Make a GET request to http://localhost:3000/albums/10
3. Try changing the id in the URL and calling the endpoint again. What do you see?

3. POST /albums should save a new album

In order for our server-side to receive and use the data sent by the client, we will need to install and use a middleware.

The JSON middleware makes it easy for our route handlers to read JSON data from the request. If the Content-Type request header indicates that the request body contains JSON data then the middleware calls JSON.parse to convert the request body into a JavaScript data structure.

To register the JSON middleware, add the following to the server code:

app.use(express.json()); // before our routes definition

In server.js, create a POST /albums endpoint that saves a new album. The album will be passed as a JSON object in the request body.

1. Add the following code to server.js:

app.post("/albums", function (req, res) {
  const newAlbum = req.body;
  albumsData.push(newAlbum);
  res.send("Album added successfully!");
});

1. Open Postman and create a new request.
2. Set the Request Type to POST.
3. Enter the URL for your endpoint, which should be http://localhost:3000/albums.
4. Set the Body Type to raw and format to JSON (application/json).
5. Enter the Album Data in the body of the request as JSON:

{
  "albumId": "13",
  "artistName": "Beyoncé",
  "collectionName": "B'Day (Deluxe Edition)",
  "artworkUrl100": "http://is5.mzstatic.com/image/thumb/Music/v4/6c/fc/6a/6cfc6a13-0633-f96b-9d72-cf56774beb4b/source/100x100bb.jpg",
  "releaseDate": "2007-05-29T07:00:00Z",
  "primaryGenreName": "Pop",
  "url": "https://www.youtube.com/embed/RQ9BWndKEgs?rel=0&controls=0&showinfo=0"
}

1. Click Send.
2. You should see the album you just created in the response.

4. DELETE /albums/:albumId should delete the album (that matches the passed albumId)

This means that DELETE /albums/2 should delete an album with the id 2 and return 200 with JSON { success: true } to the user.

The code will look like this

// notice .delete
app.delete("/albums/:albumID", function (req, res) {
  console.log("DELETE /albums route");
});

Can you work out how to remove an album using this code?

Acceptance Criteria

• I have written a server that can handle the following requests:
  • GET /albums
  • GET /albums/:albumId
  • POST /albums
  • DELETE /albums/:albumId
• I have used Postman to test my server

Resources

• Express
• Express Cheatsheet