NodeJS_Mentoring_Program

Project Structure

    .
    ├── src                       - store source files of the project
    │   └── utils
    │       ├── csv.serve.ts
    │       └── string.reverse.ts
    ├── temp                     - temporary folder which is used for csv conversion
    │   ├── csv                  -  from [./temp/csv]
    │   └── csv-parsed           -  to [./temp/csv-parsed]
    ├── test                     - the folder for testing purpose
    │   └── data
    │       └── csv.serve.data.csv
    ├── build                    - stores the output of the TypeScript compilation with [tsc]
    ├── lib                      - stores the output of the TypeScript compilation with [babel]
    ├── package-lock.json
    └── tsconfig.json
    ├── package.json
    ├── README.md

Scripts

Script name	Command	Description
postinstall	`npm run tsc && npm run babel:tsc`	Compile js-representation files with TypeScript & Babel(TypeScript plugin)
tsc	`tsc`	Compile js-representation files with TypeScript and put them into ./build folder
babel:tsc	`babel --extensions \".ts\" ./src --out-dir ./lib`	Compile js-representation files with Babel(TypeScript plugin) and put them into ./lib folder
task1	`nodemon --config ./nodemon.dev.json ./src/utils/string.reverse.ts`	Run the solution for Task 1
task2	`npm run task2:stream`	Run the solution for Task 2
task2:stream	`nodemon --config ./nodemon.dev.json ./src/utils/csv.serve.stream.ts`	Run the solution for Task 2 with usage stream approach
task2:no_stream	`nodemon --config ./nodemon.dev.json ./src/utils/csv.serve.no_stream.ts`	Run the solution for Task 2 with usage regular usage of readFile and appendFile functions
task3.1:babel	`nodemon ./lib/utils/string.reverse.js`	Run the solution for Task 3.1
task3.2:babel	`nodemon ./lib/utils/csv.serve.stream.js`	Run the solution for Task 3.2
start:dev	`nodemon ./src/app.ts`	Run the solution for the Module_2: ExpressJS server

Service API (PATH=/api/v1)

[x-access-token] all endpoints required, except /api/v1/login and /

VERB	Route	Description
GET	/	Return message: "Hello World!"

User API (PATH=/api/v1/user)

VERB	Route	Description
POST	/	Create User
GET	/list	Get list of all users (or filter by query params)
GET	/:id	Get User by ID
PUT	/:id	Update user by parameter ID
DELETE	/:id	Delete user by parameter ID (use query params to soft deletion)

User API (PATH=/api/v1/group)

VERB	Route	Description
POST	/	Create a Group
GET	/list	Get list of all groups (or filter by query params)
GET	/:id	Get Group by ID
PUT	/:id	Update a group by parameter ID
DELETE	/:id	Delete group by parameter ID (only hard deletion is supported)
POST	/user	Add a user to groups

User API (PATH=/api/v1/login)

VERB	Route	Description
POST	/	Create provide token based on sent username and password

N.B. More details in Swagger (OpenAPI) file will be added later.

Environment variables

	Default value	Description
SERVICE_ENV	dev	Environment on each service is run
JWT_SECRET	unspecified	JsonWebToken secret text to generate token
JWT_EXPIRATION_TERM	600	Time term for the token
JWT_PRIVATE_KEY	unspecified	Unsupported currently. However it is allocated for the future implementation to store path to secret key
DB_USER	unspecified	Database username
DB_PASSWORD	unspecified	Database password
DB_NAME	unspecified	Database name
DB_HOST	unspecified	Database hostname
DB_PORT	unspecified	Database port number
KABOOM	unspecified	Time term in ms when unexpected Error will throw any where in code to check safe exit from service

Task Completion

Module-7: UNIT TESTS AND CONFIG

Task 1:

Add unit tests for User entity controller methods using Jest library.
Add unit tests for Group entity controller methods using Jest.

Task 2:

The information on DB connection (connection string) should be stored in .env file and should be passed to the application using environment variables with the help of dotenv package. As an alternative package you can also use config.

Module-6: JWT AUTHORIZATION AND CORS

Task 1:

Add authorization to the already existing REST service.
Add login(username, password)method which should return JWT token.
Add a middleware which will proxy all the requests (except login) and check that HTTP Authorization header has the correct value of JWT token.
In case of the HTTP Authorization header is absent in the request, the middleware should stop further controller method execution and return HTTP 401 code (Unauthorized Error) and standard error message.
In case of HTTPAuthorization header has invalid JWT token in the request, the middleware should return HTTP code 403 (Forbidden Error) and standard error message.

Task 2:

-Add CORS middleware to access service methods from WEB applications hosted on another domains Express Cors middleware.

Module-5: LOGGING & ERROR HANDLING

Task 1:

Add express middleware which will log which service method has been invoked and which arguments have been passed to it.

Task 2:

Add express middleware which will log all unhandled errors and return a standard message with HTTP code 500(Internal Server Error). Remark: Do not modify the status code and the message for other errors like validation errors from the previous task.
Add error handling to process.on ("uncaughtException",...).
Add Unhandled promise rejection listener to log errors.

Task 3:

Every method in the controllers should log the errors which should include the following information:
- method name;
- arguments which have been passed to the method;
- error message.

Module-4: SECOND ENTITY AND MANY-TO-MANY ENTITY RELATIONSHIPS

Task 1:

Add Group entity to already existing REST service with CRUD operations;
TheGroup entity should have the following properties (you can use UUID as Group id):

export type TPermission = "READ" | "WRITE" | "DELETE" | "SHARE" | "UPLOAD_FILES";

export type TGroup = {
    id: string;
    name: string;
    permissions: TPermission[];
};

The service should provide the following CRUD operations for Group:
- Get group by id;
- Get all groups;
- Create and update a group;
- Remove group (hard delete–group data is fully removed from the DB);
Storing of groups data should be done in PostgreSQLinGroups table;
The service should follow the principles of 3-layer architecture.

Task 2:

Link User records in one table with Group records in another table.
Add a UserGroup table ("many-to-many" relationship) which will store the data describing which users are assigned to which group.
If any record gets removed from the DB, then all linked records should be removed from UserGroup as well.

Task 3:

Add addUsersToGroup(groupId, userIds) method which will allow adding users to a certain group.
Use transactions to save records in DB.

Module-3: PostgreSQL and layered architecture

Project structure example from a lecture (based on the Layered architecture approach)

   src                          - store source files of the project
    ├── app.js                  - The application entry point
    ├── api/                    - Express route controllers for all the endpoints of the application
    ├── config/                 - Environment variables and configuration related stuff
    ├── loaders/                - Split the startup process into modules
    ├── models/                 - Database models
    ├── services/               - All the business logic here
    ├── subscribes/             - Event handlers for async tasks
    ├── types/                  - Type declaration files (d.ts) for TypeScript

Task 1:

Install DB PostgreSQL on your machine or use a free web hosting services for PostgreSQL (Heroku ElephantSQL).
Write> SQL script which will create Users table in the DB and fill it in with predefined users’ collection.
Configure your REST service to work with PostgreSQL.
Use the sequelize package SequelizeJS as ORM to work with PostgreSQL.
As an alternative to sequelize you can use more low-level query-builder library KnexJS.

Task 2:

The service should adhere to 3-layer architecture principles Ideal NodeJS Project Structure and contain the following set of directories:

    ...
    ├── routers/controllers
    ├── services/
    ├── data-access/
    ├── models/
    ...

Module-2: In-memory CRUD REST service with validation

Write a simple REST service with CRUD operations for User entity.

To create REST service,use ExpressJS ExpressJS.
The User should have the following properties (you can use UUID as a user identifier (id)):

    type User = {
       id: string;
       login: string;
       password: string;
       age: number;
       isDeleted: boolean;  
   }

Service should have the following CRUD operations for User:

get user by id;
create and update user;
get auto-suggest list from limit users, sorted by login property and filtered by loginSubstringin the login property: getAutoSuggestUsers(loginSubstring, limit)
remove user (soft delete–user gets marked with isDeleted flag, but not removed from the collection).
Store user’s collection in the service memory (while the service is running).To test the service CRUD methods,you can use Postman.

Add server-side validation for create/update operations of User entity:

all fields are required;
login validation is required;
password must contain letters and numbers;
user’s age must be between 4 and 130.
In case of any property does not meet the validation requirements or the field is absent, return 400 (Bad Request) and detailed error message.
For requests validation use special packages like [joi](<https://github.com/hapijs/joi) or Express-joi-validation.

Module-1: Basics

Write a program which reads a string from the standard input stdin, reverses it and then writes it to the standard output stdout.

The program should be started from npm script via nodemon(i.e. npm run task1).
The program should be running in a stand-by mode and should not be terminated after the first-string processing

Write a program which should do the following:

Read the content of csv file from ./csv directory. Example:

    Book,Author,Amount,Price
    The Compound Effect,Darren Hardy,5,9.48
    The 7 Habits of Highly Effective People,Stephen R. Covey,4,23.48
    The Miracle Morning,Hal Elrod,10,21.34
    Influence: The Psychology of Persuasion,Robert B. Cialdini,4,12.99
    The ONE Thing,Gary Keller,1,11.18

Use the csvtojson package to convert csv file to json object.
Write the csv file content to a new txt file. Use the following format: Example

    {"book":"The Compound Effect","author":"Darren Hardy","price":9.48}
    {"book":"The 7 Habits of Highly Effective People","author":"Stephen R. Covey","price":23.48}
    {"book":"The Miracle Morning","author":"Hal Elrod","price":21.34}
    {"book":"Influence: The Psychology of Persuasion","author":"Robert B. Cialdini","price":12.99}
    {"book":"The ONE Thing","author":"Gary Keller","price":11.18}

Do not load all the content of the csv file into RAM via stream (read/write file content line by line).
In case of read/write errors, log them in the console.
The program should be started via npm script using nodemon(i.e. npm run task2).

Rewrite the above-mentioned programs to use babel and ES6 modules.

KarneyenkaDzmitry/NodeJS_Mentoring

NodeJS_Mentoring_Program

Project Structure

Scripts

Service API (PATH=/api/v1)

User API (PATH=/api/v1/user)

User API (PATH=/api/v1/group)

User API (PATH=/api/v1/login)

Environment variables

Task Completion

Module-7: UNIT TESTS AND CONFIG

Module-6: JWT AUTHORIZATION AND CORS

Module-5: LOGGING & ERROR HANDLING

Module-4: SECOND ENTITY AND MANY-TO-MANY ENTITY RELATIONSHIPS

Module-3: PostgreSQL and layered architecture

Project structure example from a lecture (based on the Layered architecture approach)

Module-2: In-memory CRUD REST service with validation

Module-1: Basics