I Built a Rule Engine
Andrew Vo-Nguyen
March 18, 2023
2 min read
I was working on a React Native project that required my app to give the user a convenient way to filter payloads based on certain criteria of each field. I started building a data structure, then the methods to consume the data structures. Before I knew it, I had taken on a side quest inside my app. Then I thought, I am basically building a rules engine inside my app. Why not extract it out to something a bit more abstract an potentially re-usable for others in the community. This is when I decided to build rules-engine-ts.
So in order to build an open source rules engine that others would want to use, there were a few criteria in my mind that had to be met. Roughly speaking these were it:
- The data structure had to be as simple as possible, yet still being able to scale.
- Safe guard the data structure using type safety and validations.
- Prioritize developer experience over optimization or code correctness.
- Use plain objects as opposed to classes so that the data structure could easily be serialized and deserialized and can be persisted in any type of data store.
- Provide as many helper functions as possible to assist the consumer with operation.
- Be specific with types, which meant creating lots and lots of types.
- Document the hell out of the work.
Overall the package took me just over 1 week to code. I was able to import it into my original React Native project and use it to build the rules engine. It was also imported into a backend Lambda to read the rules from a database and evaluate it.
The top takeaways from this experience are:
- There is a level of satisfaction in building something that fixes a real world problem for yourself and potentially others.
- If you're going to release something to the public, make sure you build it for the public (stringently unit test, be clear with your code, and even clearer with your documentation).
- It's hard to know exactly what your audience wants without proper research, so be prepared to take criticism for your implementation and be willing to change it if someone makes a good case.
- Not everything has to be a grandioso project that changes the world. Even small tools that help other developers are worth pursuing.
As of today, after being released for 5 days, there have been 536 downloads. Lets hope it can gain some traction over the next few weeks! 👊