Assignment

As usual, create a PR in your HYF assignments repository.

In the repository, create a nodejs-week1 branch from main to work on the assignment (git checkout -b nodejs-week1 )

Setup

Go to nodejs/week1 in your hyf-assignment repo:

npm init -y
npm pkg set type="module"
npm i express
npm pkg set scripts.dev="node --watch app.js"

You should ensure that the node_modules/ folder is ignored by Git:

echo node_modules/ >> .gitignore

Create app.js and as a starting point you can use the following code:

import express from "express";
const app = express();
const port = process.env.PORT || 3000;

// Support parsing JSON requests
app.use(express.json());

app.get("/", (req, res) => {
  res.send("This is a search engine");
});

app.listen(port, () => {
  console.log(`Listening on port ${port}`);
});

Part 1: Add more snippets and tags

You will continue working with the schema used in the session. This week you will build more endpoints, developing some CRUD operations to be able to add more data via your backend.

Excercise goal

We have users and users post snippets. We need to be able to post those snippets to the database and also edit or delete the snippets via backend endpoints.

We also need some categorisation mechanics. Let's add a tags table, that will store tags available to be added to our snippets, so it is easier to search them. Each snippet can have many tags and each tag can belong to many snippets.

Note: you need to modify the snippets column in the database on top of adding new tables to achieve this.

Routes

For this week's assignment, we will have two categories of routes: snippets and tags.

• The routes for snippets will go into /api/src/routers/snippets.js

• The tags routes will live in /api/src/routers/tags.js

This means that we will end up having two Routers: a snippets and tags router. You can read more about Express Routers.

Snippets

Route	HTTP method	Description
/api/snippets	GET	Returns all snippets
/api/snippets	POST	Adds a new snippet to the database
/api/snippets/:id	GET	Returns the snippet by id
/api/snippets/:id	PUT	Updates the snippet by id
/api/snippets/:id	DELETE	Deletes the snippet by id

Tags

Now that you have built the basic set of endpoints for snippets, you can get some more practice and expand your app backend by creating the same for tags:

Route	HTTP method	Description
/api/tags	GET	Returns all tags
/api/tags	POST	Adds a new tag to the database
/api/tags/:id	GET	Returns a tag by id
/api/tags/:id	PUT	Updates the tag by id
/api/tags/:id	DELETE	Deletes the tag by id

Requests

All the POST or PUT endpoints will require a request body - the information that your database will be updated with.

Responses

All the specified GET routes should respond with JSON with the available columns from the associated tables.

The GET, PUT and DELETE routes that include an /:id in the path should make sure to handle the case when the row with that ID does not exist.

Think about what special HTTP status code would be appropriate for that scenario.

You are free to decide on the response for a successful POST, PUT and DELETE request. Some ideas:

• Respond with an acknowledgement message: { "message": "Deleted snippet" }

• Respond with data from the row itself like with GET

And lastly, if the POST request is successful, the response status code should be 201 Created, as that would indicate something was created.

Knex

Your usage of Knex should be getting a bit more advanced now. You will move from knex.raw on to different knex function, for example:

• .select, .from, .where

• .insert

• .update

• .del (for deletion)

Check out the Knex cheatsheet!

Part 2: search engine

For the excercise you're going to build a search engine. The search engine will have 3 routes:

• GET /search

• GET /snippets/:id

• POST /search

GET /search

This endpoint will accept a query parameter called q, short for query. A bit confusing to have a query parameter called q(uery) but hang in there 💪

• If q is not provided, the endpoint should return all documents.

• If q is provided, the endpoint should return the documents with some field that matches the value of q.

Example response if we call GET /search?q=react:

[
  {
    "id": 2,
    "title": "React Hooks",
    "contents": "Explaining useState and useEffect with examples."
  }
]

GET /snippets/:id

This endpoint is simple: find and respond with the snippet matching the id parameter. If there is no such snippet, respond with a 404 Not Found. You can assume that the snippet IDs are unique so there's no need to handle duplicates.

POST /search

This endpoint is sort of like GET /search.

It also accepts a query parameter called q and it should behave just like GET /search. But it also accepts a field called fields in the JSON request body. fields is an object where it will be possible to filter by specific fields.

Example request:

POST /search
{
    "fields": {
        "tags": "React"
    }
}

Response to the example request:

[
  {
    "id": 1,
    "title": "React Hooks",
    "contents": "Explaining useState and useEffect with examples.",
    "tags": ["React"]
  }
]

If both q (query parameter) and fields (in body) are provided, we should respond with status 400 Bad Request and explain that both can't be provided.