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About This project is a summary of this back-end trimester: authentication, NodeJS, MongoDB, Redis, pagination and background processing

0x04. Files manager Back-end JavaScript ES6 NoSQL MongoDB Redis NodeJS ExpressJS Kue

This project is a summary of this back-end trimester: authentication, NodeJS, MongoDB, Redis, pagination and background processing.

The objective is to build a simple platform to upload and view files:

User authentication via a token List all files Upload a new file Change permission of a file View a file Generate thumbnails for images You will be guided step by step for building it, but you have some freedoms of implementation, split in more files etc… (utils folder will be your friend)

Of course, this kind of service already exists in the real life - it’s a learning purpose to assemble each piece and build a full product.

Enjoy!

Resources Read or watch:

Node JS getting started - https://nodejs.org/en/docs/guides/getting-started-guide Process API doc - https://node.readthedocs.io/en/latest/api/process/ Express getting started - https://expressjs.com/en/starter/installing.html Mocha documentation - https://mochajs.org/ Nodemon documentation - https://github.com/remy/nodemon#nodemon MongoDB - https://github.com/mongodb/node-mongodb-native Bull - https://github.com/OptimalBits/bull Image thumbnail - https://www.npmjs.com/package/image-thumbnail Mime-Types - https://www.npmjs.com/package/mime-types Redis - https://github.com/redis/node-redis

Learning Objectives At the end of this project, you are expected to be able to explain to anyone, without the help of Google:

how to create an API with Express how to authenticate a user how to store data in MongoDB how to store temporary data in Redis how to setup and use a background worker

Tasks 0. Redis utils mandatory Score: 0.0% (Checks completed: 0.0%) Inside the folder utils, create a file redis.js that contains the class RedisClient.

RedisClient should have:

the constructor that creates a client to Redis: any error of the redis client must be displayed in the console (you should use on('error') of the redis client) a function isAlive that returns true when the connection to Redis is a success otherwise, false an asynchronous function get that takes a string key as argument and returns the Redis value stored for this key an asynchronous function set that takes a string key, a value and a duration in second as arguments to store it in Redis (with an expiration set by the duration argument) an asynchronous function del that takes a string key as argument and remove the value in Redis for this key After the class definition, create and export an instance of RedisClient called redisClient.

1. MongoDB utils mandatory Score: 0.0% (Checks completed: 0.0%) Inside the folder utils, create a file db.js that contains the class DBClient.

DBClient should have:

the constructor that creates a client to MongoDB: host: from the environment variable DB_HOST or default: localhost port: from the environment variable DB_PORT or default: 27017 database: from the environment variable DB_DATABASE or default: files_manager a function isAlive that returns true when the connection to MongoDB is a success otherwise, false an asynchronous function nbUsers that returns the number of documents in the collection users an asynchronous function nbFiles that returns the number of documents in the collection files After the class definition, create and export an instance of DBClient called dbClient.

2. First API mandatory Score: 0.0% (Checks completed: 0.0%) Inside server.js, create the Express server:

it should listen on the port set by the environment variable PORT or by default 5000 it should load all routes from the file routes/index.js Inside the folder routes, create a file index.js that contains all endpoints of our API:

GET /status => AppController.getStatus GET /stats => AppController.getStats Inside the folder controllers, create a file AppController.js that contains the definition of the 2 endpoints:

GET /status should return if Redis is alive and if the DB is alive too by using the 2 utils created previously: { "redis": true, "db": true } with a status code 200 GET /stats should return the number of users and files in DB: { "users": 12, "files": 1231 } with a status code 200 users collection must be used for counting all users files collection must be used for counting all files Terminal 1: bob@dylan:~$ npm run start-server Server running on port 5000 ... Terminal 2:

bob@dylan:$ curl 0.0.0.0:5000/status ; echo "" {"redis":true,"db":true} bob@dylan:$ bob@dylan:$ curl 0.0.0.0:5000/stats ; echo "" {"users":4,"files":30} bob@dylan:$

3. Create a new user mandatory Score: 0.0% (Checks completed: 0.0%) Now that we have a simple API, it’s time to add users to our database.

In the file routes/index.js, add a new endpoint:

POST /users => UsersController.postNew Inside controllers, add a file UsersController.js that contains the new endpoint:

POST /users should create a new user in DB:

To create a user, you must specify an email and a password If the email is missing, return an error Missing email with a status code 400 If the password is missing, return an error Missing password with a status code 400 If the email already exists in DB, return an error Already exist with a status code 400 The password must be stored after being hashed in SHA1 The endpoint is returning the new user with only the email and the id (auto generated by MongoDB) with a status code 201 The new user must be saved in the collection users: email: same as the value received password: SHA1 value of the value received

4. Authenticate a user mandatory Score: 0.0% (Checks completed: 0.0%) In the file routes/index.js, add 3 new endpoints:

GET /connect => AuthController.getConnect GET /disconnect => AuthController.getDisconnect GET /users/me => UserController.getMe Inside controllers, add a file AuthController.js that contains new endpoints:

GET /connect should sign-in the user by generating a new authentication token:

By using the header Authorization and the technique of the Basic auth (Base64 of the :), find the user associate to this email and with this password (reminder: we are storing the SHA1 of the password) If no user has been found, return an error Unauthorized with a status code 401 Otherwise: Generate a random string (using uuidv4) as token Create a key: auth_ Use this key for storing in Redis (by using the redisClient create previously) the user ID for 24 hours Return this token: { "token": "155342df-2399-41da-9e8c-458b6ac52a0c" } with a status code 200 Now, we have a way to identify a user, create a token (= avoid to store the password on any front-end) and use this token for 24h to access to the API!

Every authenticated endpoints of our API will look at this token inside the header X-Token.

GET /disconnect should sign-out the user based on the token:

Retrieve the user based on the token: If not found, return an error Unauthorized with a status code 401 Otherwise, delete the token in Redis and return nothing with a status code 204 Inside the file controllers/UsersController.js add a new endpoint:

GET /users/me should retrieve the user base on the token used:

Retrieve the user based on the token: If not found, return an error Unauthorized with a status code 401 Otherwise, return the user object (email and id only)

5. First file mandatory Score: 0.0% (Checks completed: 0.0%) In the file routes/index.js, add a new endpoint:

POST /files => FilesController.postUpload Inside controllers, add a file FilesController.js that contains the new endpoint:

POST /files should create a new file in DB and in disk:

Retrieve the user based on the token: If not found, return an error Unauthorized with a status code 401 To create a file, you must specify: name: as filename type: either folder, file or image parentId: (optional) as ID of the parent (default: 0 -> the root) isPublic: (optional) as boolean to define if the file is public or not (default: false) data: (only for type=file|image) as Base64 of the file content If the name is missing, return an error Missing name with a status code 400 If the type is missing or not part of the list of accepted type, return an error Missing type with a status code 400 If the data is missing and type != folder, return an error Missing data with a status code 400 If the parentId is set: If no file is present in DB for this parentId, return an error Parent not found with a status code 400 If the file present in DB for this parentId is not of type folder, return an error Parent is not a folder with a status code 400 The user ID should be added to the document saved in DB - as owner of a file If the type is folder, add the new file document in the DB and return the new file with a status code 201 Otherwise: All file will be stored locally in a folder (to create automatically if not present): The relative path of this folder is given by the environment variable FOLDER_PATH If this variable is not present or empty, use /tmp/files_manager as storing folder path Create a local path in the storing folder with filename a UUID Store the file in clear (reminder: data contains the Base64 of the file) in this local path Add the new file document in the collection files with these attributes: userId: ID of the owner document (owner from the authentication) name: same as the value received type: same as the value received isPublic: same as the value received parentId: same as the value received - if not present: 0 localPath: for a type=file|image, the absolute path to the file save in local Return the new file with a status code 201

6. Get and list file mandatory Score: 0.0% (Checks completed: 0.0%) In the file routes/index.js, add 2 new endpoints:

GET /files/:id => FilesController.getShow GET /files => FilesController.getIndex In the file controllers/FilesController.js, add the 2 new endpoints:

GET /files/:id should retrieve the file document based on the ID:

Retrieve the user based on the token: If not found, return an error Unauthorized with a status code 401 If no file document is linked to the user and the ID passed as parameter, return an error Not found with a status code 404 Otherwise, return the file document GET /files should retrieve all users file documents for a specific parentId and with pagination:

Retrieve the user based on the token: If not found, return an error Unauthorized with a status code 401 Based on the query parameters parentId and page, return the list of file document parentId: No validation of parentId needed - if the parentId is not linked to any user folder, returns an empty list By default, parentId is equal to 0 = the root Pagination: Each page should be 20 items max page query parameter starts at 0 for the first page. If equals to 1, it means it’s the second page (form the 20th to the 40th), etc… Pagination can be done directly by the aggregate of MongoDB

7. File publish/unpublish mandatory Score: 0.0% (Checks completed: 0.0%) In the file routes/index.js, add 2 new endpoints:

PUT /files/:id/publish => FilesController.putPublish PUT /files/:id/publish => FilesController.putUnpublish In the file controllers/FilesController.js, add the 2 new endpoints:

PUT /files/:id/publish should set isPublic to true on the file document based on the ID:

Retrieve the user based on the token: If not found, return an error Unauthorized with a status code 401 If no file document is linked to the user and the ID passed as parameter, return an error Not found with a status code 404 Otherwise: Update the value of isPublic to true And return the file document with a status code 200 PUT /files/:id/unpublish should set isPublic to false on the file document based on the ID:

Retrieve the user based on the token: If not found, return an error Unauthorized with a status code 401 If no file document is linked to the user and the ID passed as parameter, return an error Not found with a status code 404 Otherwise: Update the value of isPublic to false And return the file document with a status code 200

8. File data mandatory Score: 0.0% (Checks completed: 0.0%) In the file routes/index.js, add one new endpoint:

GET /files/:id/data => FilesController.getFile In the file controllers/FilesController.js, add the new endpoint:

GET /files/:id/data should return the content of the file document based on the ID:

If no file document is linked to the ID passed as parameter, return an error Not found with a status code 404 If the file document (folder or file) is not public (isPublic: false) and no user authenticate or not the owner of the file, return an error Not found with a status code 404 If the type of the file document is folder, return an error A folder doesn't have content with a status code 400 If the file is not locally present, return an error Not found with a status code 404 Otherwise: By using the module mime-types, get the MIME-type based on the name of the file Return the content of the file with the correct MIME-type

9. Image Thumbnails mandatory Update the endpoint POST /files endpoint to start a background processing for generating thumbnails for a file of type image:

Create a Bull queue fileQueue When a new image is stored (in local and in DB), add a job to this queue with the userId and fileId Create a file worker.js:

By using the module Bull, create a queue fileQueue Process this queue: If fileId is not present in the job, raise an error Missing fileId If userId is not present in the job, raise an error Missing userId If no document is found in DB based on the fileId and userId, raise an error File not found By using the module image-thumbnail, generate 3 thumbnails with width = 500, 250 and 100 - store each result on the same location of the original file by appending _ Update the endpoint GET /files/:id/data to accept a query parameter size:

size can be 500, 250 or 100 Based on size, return the correct local file If the local file doesn’t exist, return an error Not found with a status code 404 Terminal 3: (start the worker)

bob@dylan:~$ npm run start-worker ... Terminal 2:

bob@dylan:$ curl 0.0.0.0:5000/connect -H "Authorization: Basic Ym9iQGR5bGFuLmNvbTp0b3RvMTIzNCE=" ; echo "" {"token":"f21fb953-16f9-46ed-8d9c-84c6450ec80f"} bob@dylan:$ bob@dylan:$ python image_upload.py image.png f21fb953-16f9-46ed-8d9c-84c6450ec80f 5f1e881cc7ba06511e683b23 {'id': '5f1e8896c7ba06511e683b25', 'userId': '5f1e7cda04a394508232559d', 'name': 'image.png', 'type': 'image', 'isPublic': True, 'parentId': '5f1e881cc7ba06511e683b23'} bob@dylan:$ ls /tmp/files_manager/ 2a1f4fc3-687b-491a-a3d2-5808a02942c9 51997b88-5c42-42c2-901e-e7f4e71bdc47 6dc53397-8491-4b7c-8273-f748b1a031cb 6dc53397-8491-4b7c-8273-f748b1a031cb_100 6dc53397-8491-4b7c-8273-f748b1a031cb_250 6dc53397-8491-4b7c-8273-f748b1a031cb_500 bob@dylan:$ bob@dylan:$ curl -XGET 0.0.0.0:5000/files/5f1e8896c7ba06511e683b25/data -so new_image.png ; file new_image.png new_image.png: PNG image data, 471 x 512, 8-bit/color RGBA, non-interlaced bob@dylan:$ bob@dylan:$ curl -XGET 0.0.0.0:5000/files/5f1e8896c7ba06511e683b25/data?size=100 -so new_image.png ; file new_image.png new_image.png: PNG image data, 100 x 109, 8-bit/color RGBA, non-interlaced bob@dylan:$ bob@dylan:$ curl -XGET 0.0.0.0:5000/files/5f1e8896c7ba06511e683b25/data?size=250 -so new_image.png ; file new_image.png new_image.png: PNG image data, 250 x 272, 8-bit/color RGBA, non-interlaced bob@dylan:~$

10. Tests! #advanced Of course, a strong and stable project can not be good without tests.

Create tests for redisClient and dbClient.

Create tests for each endpoints:

GET /status GET /stats POST /users GET /connect GET /disconnect GET /users/me POST /files GET /files/:id GET /files (don’t forget the pagination) PUT /files/:id/publish PUT /files/:id/unpublish GET /files/:id/data

11. New user - welcome email #advanced Update the endpoint POST /users endpoint to start a background processing for sending a “Welcome email” to the user:

Create a Bull queue userQueue When a new user is stored (in DB), add a job to this queue with the userId Update the file worker.js:

By using the module Bull, create a queue userQueue Process this queue: If userId is not present in the job, raise an error Missing userId If no document is found in DB based on the userId, raise an error User not found Print in the console Welcome ! In real life, you can use a third party service like Mailgun to send real email. These API are slow, (sending via SMTP is worst!) and sending emails via a background job is important to optimize API endpoint.