stackoverflow-code-lld

https://stackoverflow.com/users/9093208/rohit-maurya

Requirements

1- Post questions and add Category / Tag
2- Search based on title, tag or question id
3- Add answers to questions
4- Upvote and Downvote to questions and answers
5- View users dashboard [earned badges]
6- Send notification to the user 1, if any other user add commente/upvote/downvote/answer to the user 1 activity

API Details

GET Methods

1- View all post (all questions with tag)
   localhost:8080/post
2- View by question id or title
   localhost:8080/post/<question_id>/ans
   localhost:8080/post/<title>/ans
3- Upvote answer/question
   localhost:8080/post/<question_id>/ans/<answer_id>/upvote
   localhost:8080/post/<question_id>/ques/upvote
4- Down vote question/answer
   localhost:8080/post/<question_id>/ans/<answer_id>/downvote
   localhost:8080/post/<question_id>/ques/downvote
5- View user id dashboard
   localhost:8080/user/<user_id>
6- Send notification [search in db who all are associated with eventId and notify them]
   localhost:8080/notification/event_id

Post Methods

1- Add new question
   localhost:8080/user/<user_id>
   Method POST

   Request body:

   {
   "question": "How to learn to code lld in Java",
   "tags": [
           {
            "tagName": "Java"
            }
   ]
   }
 2- Add new answer for question id <question_id>
    localhost:8080/post/<question_id>

    Method :POST


    Request Body
    {
    "answer": "If you learn Design Pattern, you can learn how to code lld in any language"
 3- Upvote answer
    localhost:8080/post/<question_id>/ans/<answer_id>/upvote
    Method : POST
 4- Downvote answer
    localhost:8080/post/<question_id>/ans/<answer_id>/downvote
    Method : POST

LLD Diagram / Class Diagram

Database table design

User_Table : user_id, name, email_id, designation, reputation, badge_id

Question_Table : qes_id, description, title, user_id, TimeStamp, total_vote_count

                  total_vote_count => it will help to fetch all vote for a particular question, helps to reduce query

Answer_Table : asn_id, description, user_id, event_id, event_type, TimeStamp, total_vote_count

                event_id => comment on answer/question or Answer for question
                event_type => comment or answer
                ans_Id : use same table for both comment as well as Answer

Badge_Table : badge_id, type

                in this table badge_id and type both together will be PK, the reason of having both togehter as key is one user
                may achive multiple badges