TODO LIST API

• Plan: https://docs.google.com/document/d/1HzEkPgcPmaZr2aXNdBmNr2lR0lxgDbRHEJrFaxJjstc/edit?usp=sharing

• Documents folder: database and postman collection

SUMMARY

• 1. What is this project used for?
• 2. What does this project can do?
• 3. 🚀 What technologies does this project use?
• 4. What is circular dependency?
  • 4.1. Definition
  • 4.2. How to detect it
• 5. How to run this project?
  • 5.1. First method: with docker
  • 5.2. Second method: without docker

1. What is this project used for?

This project is a simple API for managing todo list.

2. What does this project can do?

• Create a new task
• Update a task
• Delete a task
• Get all tasks
• Get a task by id
• Get all parent tasks of a task
• Create / Delete a reference between tasks
• Detect a circular dependency in tasks
• Prevent circular dependency when adding new reference
• Periodically check tasks that are about to expire and send email notifications

3. 🚀 What technologies does this project use?

• NodeJS
• ExpressJS
• MySQL
• Redis
• Nodemailer
• JWT
• Docker

4. What is circular dependency?

4.1. Definition

• Firstly, you can see the image below describe how task reference each other

• Each task can have multiple parent tasks and multiple child tasks

• Circular dependency problem occurs when Task 3 depends on Task 6 and Task 6 depends on Task 7 and Task 7 depends on Task 3 and... We have now got a circular dependency.😒😒

4.2. How to detect it

• Look at the image, we can see that like a graph, where each Node depends on other Nodes.
• So, how to detect it? The idea is when a Node is seen, but it is not resolved yet, we can say that we have a circular dependency.
• For example, we have a graph with path: 3 -> 6 -> 7 -> 3
• Task 3 in the end of path is seen at the top, but it is not resolved yet, because of Task 3 depends on Task 6 and so on.

This is how we can detect it by Pseudocode

function dep_resolve(node, visited, unFinished) {

  unFinished.push(node);

  for parentNode in node.parents {

    if parentNode not in visited {
      if parentNode in unFinished {

        // we detected circular dependency here
      }
      dep_resolve(parentNode, visited, unFinished);
    }
  }
  visited.push(node);
  unFinished.remove(node);
}

// call function

type Node = {
  id: number,
  parents: Node[]
}

let firstNode : Node = {
  id: ...,
  parents: [ ... ]
}

dep_resolve(firstNode, [], []);

5. How to run this project?

5.1. First method: with docker

• Clone this project
• Create .env file in the root directory with following format

  APP_PORT= 8000

  DB_HOST= localhost                     (OPTIONAL)
  DB_PORT= 3306                          (OPTIONAL)
  DB_USER= root                          (OPTIONAL)
  DB_PASS= password                      (OPTIONAL)
  DB_NAME= tododb                        (OPTIONAL)

  REDIS_HOST= localhost                  (OPTIONAL)
  REDIS_PORT= 5678                       (OPTIONAL)
  REDIS_PASSWORD= password               (OPTIONAL)

  JWT_SECRET_KEY=secret
  ACCESS_TOKEN_EXPIRES_IN=1d

  EMAIL_USER = your@gmail.com            (OPTIONAL)
  EMAIL_PASS = 'umtj jklmn mvtg wrnz'    (OPTIONAL)
  EMAIL_HOST = gmail                     (OPTIONAL)

• Run the following command:

  docker-compose up --build

5.2. Second method: without docker

• Clone this project
• Create .env file in the root directory with following format

  APP_PORT= 8000

  DB_HOST= localhost
  DB_PORT= 3306
  DB_USER= root
  DB_PASS= password
  DB_NAME= tododb

  REDIS_HOST= localhost
  REDIS_PORT= 5678
  REDIS_PASSWORD= password

  JWT_SECRET_KEY=secret
  ACCESS_TOKEN_EXPIRES_IN=1d

  EMAIL_USER = your@gmail.com
  EMAIL_PASS = 'umtj jklmn mvtg wrnz'
  EMAIL_HOST = gmail

• Run the following command:

Step 1: Install dependencies

  npm install

Step 2: Run project

Option 1:

  npm run dev    # for development

Option 2:

  npm run build  # for build
  npm run start  # for run bundle code

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