Show HN: Parse your Postgres queries into a fully-typed AST in TypeScript
(github.com)5 points by aleclarsoniv a day ago | 2 comments
Hey all, I'm the creator of @pg-nano/pg-parser. I'm using it in pg-nano[1] to statically analyze Postgres schemas spread across multiple SQL files for a couple of reasons:
1. Each CREATE statement needs to be in topological order, so pg-nano's dev command can execute them without issue.
2. pg-nano has a plugin system like Vite that allows SQL generation based on the parsed schema.
Probably to the surprise of no one, working with an untyped AST feels like you're back in the days of JavaScript, because well... you are. Most of you know by now just how great TypeScript and static types in general are, especially if you appreciate SQL.
So why is this project worth sharing with you?
Well, writing the AST type definitions by hand would have taken me way too much time. It would also be a bear to keep up-to-date as Postgres continues to evolve.
To my surprise, I discovered that libpg_query, the C library used under-the-hood, includes JSON definitions in their /srcdata/ folder. I figured I could use them to generate the type definitions. Genius, right? Okay... maybe not genius, but still cool, I think.
You see, those JSON definitions provided by libpg_query? They don't exactly contain the TypeScript definitions (was that obvious?). No, no. I had to translate them into TypeScript definitions. (I'm sure you could have done it, yes yes. But did you? No siree bob)
It was pain-staking, but overall really not too hard. Time-consuming? Yes, but not as much as writing the type definitions by hand. So... was it worth it? Only time will tell. I hope you find it as useful as I do. And that's all I've got, so thanks for reading.
P.S. The build for Windows is broken, so if anyone could lend a hand, you would be a true hero.
[1]: https://github.com/pg-nano/pg-nano (not ready for production use)
ardsh 18 hours ago |
This is interesting. You seem to provide extra functionality besides the typescript types over libpg-query, like the walk function, right? I assume that's the reason these changes can't be easily merged into the main library and you chose to fork entirely.
As an aside, do you think it's possible to use your libraries to get the return type of an arbitrary postgres query, even if it's dynamic? I have a library that requires users to write the return type of queries manually always, and I'd like to automate that step.