For developersHow to build a HackerNews Clone using Redis
Hacker News (sometimes abbreviated as HN) is a social news website focusing on computer science and entrepreneurship. It developed as a project of Graham's company Y Combinator, functioning as a real-world application of the Arc . programming language which Graham co-developed.
This is a HackerNews clone built upon React, NextJS as a frontend and NodeJS, ExpressJS & Redis as a backend. This application uses JSON for storing and searching the data in Redis.
#Step 1. Install the prerequisites
Install the below packages:
- NPM v7.8.0
- NODE v15.10.0
#Step 2. Create Redis Cloud database
Redis is an open source, in-memory, key-value data store most commonly used as a primary database, cache, message broker, and queue. Redis is popular among the developers as it delivers sub-millisecond response times, enabling fast and powerful real-time apps in industries such as gaming, fintech, ad-tech, social media, healthcare, and IoT.
Redis Cloud is a fully-managed cloud service for hosting and running your Redis dataset in a highly-available and scalable manner, with predictable and stable top performance. Redis Cloud allows you to run Redis server over the Cloud and access instance via multiple ways like Redis Insight, Redis command line as well as client tools. You can quickly and easily get your apps up and running with Redis Cloud through its Redis Heroku addons , just tell us how much memory you need and get started instantly with your first Redis database. You can then add more Redis databases (each running in a dedicated process, in a non-blocking manner) and increase or decrease the memory size of your plan without affecting your existing data.
Follow this link to create a Redis Cloud account with 2 databases.
Save the database endpoint URL and password for our future reference
#Step 3. Clone the repository
#Step 4. Setting up environment variables
Copy .env.sample to .env and provide the values as shown below:
#Step 5. Run the developer environment
#Step 6. Pull Hacker News API to seed database
Using API, it pulls the latest hackernews data. Next, you need to seed top stories from hacker news. First create a moderator with moderator:password123
#Step 7. Access the HackerNews URL
Open https://localhost:3001 and you should be able to access the HackerNews login screen as shown below:
#How it works
#By Screens
#Signup
- Make sure user(where username is andy1) does not exist.
- Get and increase the next id in users collection.
- Create user:63 hash and json.(json also collects authToken and password hash etc)
#Login
- Find user
- Make sure password is correct
- Compare password and new password hash and create cookie if it's successful
#Item list page
- Check if user has toggled hidden attribute on a specific item.
- If that is not null
- If it's empty array
- Get all items from Redis usingÂ
JSON.MGET
- Get items posted within last 1 week
NOTEIn this case, 1615652598 is a timestamp of 1 week ealier than current timestamp
#Item Detail
- Get the item object first
- Find item:1 's root comments
- Get those comments
- Using children of each comment, fetch children comments
- Iterate this over until all comments are resolved
#Submit
- Get next item's id and increase it
- Create hash and index
#Update Profile
- Get the user
- Update new user
#Moderation Logs screen
- Find all moderation logs
- Get that moderation logs
#Search
- Get items that contains "fa"
- Get those items via json
#Example commands
#There are 2 type of fields, indexed and non-indexed
- Indexed fields will be stored in hash using HSET/HGET.
- Non-indexed fields will be stored in JSON.
- Create an index
When schema is created, it should created index.
- Drop search index
Should drop/update index if the schema has changed
- Get search info
Validate if the fields are indexed properly. If not, it will update the index fields or drop/recreate.
- Create a new user
It will require new hash and new JSON record
- Update a user
- Find user with username 'andy'
- Find the user's hash first
2. Fetch the JSON object to get the related JSON object
- Find user whose id is andy1 or andy2
- Find user whose id is not andy1 or andy2
- Find user whose id is andy1 or username is andy
- Find user whose id is andy1 and username is andy
- Find first 10 users order by username
- Find next 10 users
- Get from JSON from multiple keys
#References
- Learn more about JSON in Redis in the Redis quick start tutorial.
- How to build shopping cart app using NodeJS and JSON in Redis
- Indexing, Querying, and Full-Text Search of JSON Documents with Redis