Simon Willison’s Weblog

Tuesday, 3rd May 2022

Simple declarative schema migration for SQLite (via) This is an interesting, clearly explained approach to the database migration problem. Create a new in-memory database and apply the current schema, then run some code to compare that with the previous schema—which tables are new, and which tables have had columns added. Then apply those changes. I’d normally be cautious of running something like this because I can think of ways it could go wrong—but SQLite backups are so quick and cheap (just copy the file) that I could see this being a relatively risk-free way to apply migrations. # 6:07 pm

Web Scraping via Javascript Runtime Heap Snapshots (via) This is an absolutely brilliant scraping trick. Adrian Cooney figured out a way to use Puppeteer and the Chrome DevTools protocol to take a heap snapshot of all of the JavaScript running on a web page, then recursively crawl through the heap looking for any JavaScript objects that have a specified selection of properties. This allows him to scrape data from arbitrarily complex client-side web applications. He built a JavaScript library and command line tool that implements the pattern. # 12:51 am

2022 » May