Q&A Platform Development (Questions and Answers)
A Q&A platform is a structured knowledge base built through community questions and answers. Key mechanics: voting on useful answers, marking "accepted answer", reputation system, tags as navigation. References: Stack Overflow, Quora, Mail.ru Answers.
Data Model
Question
├── title (indexed for search)
├── body (rich text, with code examples)
├── tags[] → Tag
├── votes_count (denormalized counter)
├── answers_count
├── accepted_answer_id → Answer
└── author_id → User
Answer
├── question_id → Question
├── body (rich text)
├── votes_count
├── is_accepted BOOLEAN
└── author_id → User
Vote
├── user_id, votable_type, votable_id
├── value INT (1 or -1)
└── PRIMARY KEY (user_id, votable_type, votable_id)
Voting and Reputation System
Voting is the central mechanism. Rules similar to Stack Overflow:
- +10 to author reputation per upvote on answer
- +5 per upvote on question
- −2 per downvote (and −1 to downvoter)
- +15 for accepted answer
Reputation unlocks privileges: at N reputation—can edit others' questions, vote to close, no CAPTCHA.
Prevent vote manipulation: can't vote on own posts, IP restrictions, vote ring detection algorithm.
Tags as Navigation
Tags are the primary way to find content. Each question has 1–5 tags. Tag page—list of questions with that tag + tag description (wiki article on topic).
Tag autocomplete when creating question: Meilisearch or PostgreSQL ILIKE against existing tags. Tag synonyms: javascript and js → one tag.
Duplicate Detection
When creating question—automatic search for similar ones. If duplicate found—question may be closed with link to original. Similar search: Elasticsearch with fuzzy matching or vector search (sentence embeddings for semantic similarity).
Code Formatting
For technical Q&A—mandatory syntax highlighting. In editor: Markdown with triple backticks ```python. Rendering: highlight.js or Prism.js with auto language detection.
Community Moderation
- Flags: users mark inappropriate content
- Close question: off-topic questions, duplicates, too broad—closed by vote
- Edit others' posts—above reputation threshold and via review queue
- Reject reason: when rejecting suggested edit—explain reason
Gamification
Badges for achievements: first answer, accepted answer, 100 upvotes, N days in a row. Leaderboard by month/year by reputation.
Timeline
MVP (questions/answers, voting, tags, accepted answer, basic reputation): 6–10 weeks. Full-featured Q&A platform with gamification, moderation, search, mobile app: 3–5 months.