Gren does not have native database support (yet). For now it is recommended to use some form of db-over-http. In this example I am using ws4sqlite (via docker) to query sqlite over HTTP on the backend, and prisma for database migrations and seeding (via the getting started guide).
- See
server/src/Main.grenfor querying the db over ws4sqlite. - See
package.jsonfor the prisma and ws4sqlite integration.
With docker or docker desktop running:
npm install
npm run dev
This will spin up the prettynice dev server that auto-rebuilds on file change,
and a docker container running ws4sqlite pointed at prisma/dev.db that will be removed when you stop the npm process.
(running in prod TBD, but the short version is npx prettynice build --optimize && npm start for the app,
and a more resiliant and secure ws4sqlite setup for the db)
If you aren't familiar with ports, see this elm guide, which also applies to gren.
You could interface directly with prisma using server-side ports, but it introduces some extra complexity due to the decoupled nature of ports.
To query a database over ports, you'll need both an outgoing port for the query, and an incoming port for the result. But because ports are Cmds, you can't have both in the same update cycle. So you need a way to save the response to send later when you receive the results. This means you need to give each request a unique ID, map that to a response on your model, pass it through the ports, and make extra-sure you are handling errors properly in your js so you don't end up with dangling requests.
Future versions of prettynice and/or gren will have a better way to call js with a Task-like interface that is composable, but until then, I recommend sticking with this or another form of db-over-http so you can keep all your db interaction in gren.
For a database-over-ports example, see examples/next/database-ports.