• My List Feature
  • Live service Details
  • Setup Instructions
  • Run Test Cases
  • API Desgin
    • Approach 1
    • Approach 2
  • DB Models
    • Approach 1
    • Approach 2
      • Design Decision
    • Sequence Diagram
  • CI/CD
  • HighLights
  • What can be improved?

---

My List Feature

Live service Details

HOST: https://stage-expressapp.onrender.com

API endpoints

• POST https://stage-expressapp.onrender.com/api/mylist/

{
    "userId": "51cface4-5a2c-4eaf-a4df-4c4b736bcf9d",
    "itemId": "51cface4-5a2c-4eaf-a4df-4c4b736bcf3d",
    "itemType": "Movie"
}

• GET https://stage-expressapp.onrender.com/api/mylist?userId=51cface4-5a2c-4eaf-a4df-4c4b736bcf9d&page=1&limit=10
• DELETE https://stage-expressapp.onrender.com/api/mylist/

{
  "userId": "51cface4-5a2c-4eaf-a4df-4c4b736bcf9d",
    "itemId": "51cface4-5a2c-4eaf-a4df-4c4b736bcf4d"
}

Setup Instructions

Action	Command
💻 Install dependencies	npm install
⚙️ Setup environment variables. Create a .env file	MONGODB_URI=mongodb://localhost:27017/mylist PORT=3000
⚡ Run Script to initialize DB	npx ts-node initializeDBScript.ts
🚀 Run the application	npm run dev-start

---

Run Test Cases

npm test

---

API Desgin

Approach 1

HTTP Method	API Endpoint	Request Body	Query Parameters
❇️ GET	/api/mylist	-	page=1&limit=10
✏️ POST	/api/mylist	userId:"UUID",itemId:"UUID", itemType:"Movie/ TvSHow"	-
❌ DELETE	/api/mylist	userId:"UUID",itemId:"UUID"	-

Approach 2

HTTP Method	API Endpoint	Request Body	Query Parameters
❇️ GET	/api/user/:user_id/mylist	-	page=1&limit=10
✏️ POST	/api/user/:user_id/mylist	itemId, itemType	-
❌ DELETE	/api/user/:user_id/mylist/:item_id	-	-

---

DB Models

Approach 1

Put myList field inside User Schema

User: {
    id: string,
    username: string,
    ...
    ...
    myList: {
        itemId: string,
        itemType: string,
        dateAddedOn: Date,
    }
}

✅ PROS:

• ✔️ Faster: No need to make extra call to fetch myList data.
• ✔️ Mylist information can be fetched initially from /api/me and save in local cache
• ✔️ Scalable: Any additional metadata can be added

🚨 CONS:

• ❗Tight Coupling: Dependency on User Schema
• ❗Not preferable for microservice arcitechure
• ❗UserService and MyList Service can not scale independently

Approach 2

Consider myList as a separate collection

== 2.1 ==

User: {
    id: string,
    username: string,
    ...
    ...
}
    
myList: {
    userId: string,
    itemId: string,
    itemType: string,
    dateAddedOn: Date,
}

✅ PROS:

• ✔️ ListItems can be handled separately for all users
• ✔️ Addition and removal of new record is faster
• ✔️ Mongo Can filter or sort on the dateAddedOn field easily

🚨 CONS:

• ❗ Need to touch multiple documents to fetch myList of single user.
• ❗ Slower GET request

== 2.2 ==

User: {
    id: string,
    username: string,
    ...
    ...
}

myList: {
    userId: string,
    wishList: [{
        itemId: string,
        itemType: string,
        dateAddedOn: Date,
    }]
}

✅ PROS:

• ✔️ List of items for a single user can be fetched from a single document
• ✔️ Faster GET request
• ✔️ FutureProof / Scalable: Can add user's metadata to this schema

🚨 CONS:

• ❗ Nested Array of objects difficult to handle(filter / sort) in Mongo.
• ❗ Removal of item from list is slower

Design Decision

Assumption: We have monolithic service

• Choosing first approach considering
  • Easier to implement
  • Low Maintenance
  • High performance (GET/POST)

---

Sequence Diagram

sequenceDiagram
    participant Client
    participant BE
    participant Mongo

    Note over Client,Mongo: Add to my list
    autonumber 1

    Client ->> BE: POST /api/myList/ {userId, ItemId, ...}
    BE -->> BE: Validates request
    BE -->> Mongo: Fetch User by userId
    BE -->> BE: add item to list if ItemId not in list
    BE ->> Client: Success (201)

    Note over Client,Mongo: Remove Item from list
    autonumber 1

    Client ->> BE: DELETE /api/myList/ {userId, ItemId}
    BE -->> BE: Validates request
    BE -->> Mongo: Fetch User by userId
    BE -->> BE: remove item from the list if ItemId is present in list
    BE ->> Client: Success (201)

    Note over Client,Mongo: List My Items
    autonumber 1

    Client ->> BE: GET /api/myList?userid:123
    BE -->> Mongo: Fetch User by userId
    BE ->> Client: Success (201), return MyList

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---

CI/CD

• For CI/CD: Render Pipeline
• Deployed On: Render Cloud

graph LR
A[Developer] -- 1. Push Commit to Origin --> B((Github))
B -- 2. Trigger Pipeline--> C(Render)
C -- 3. Pull latest code --> B

C -- Build and deploy --> D{Render Cloud}

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HighLights

• MongoDB Integration
• Script to initialize database
• Write Unit test cases
• Validate request body: Using Joi
• Generate random values: using Faker
• CI/CD
• Deploy on any cloud service

What can be improved?

1. Check for test coverage results in CI/CD pipeline
2. Setup Pre-Commit hooks to ensure
   1. Consistent commit messages
   2. Language standards: linting
3. Map Foreign Key in MyList
4. Make file to setup repository with single command