feat: enable load_extensions config for connections

[bkono]

Opening this to start a discussion. This is an attempt to implement this comment from issue #136, piggybacking on the hard work done in #160.

I needed this to be able to actively use extensions with Ecto inside a Phoenix app. There's a few scenarios where it comes in handy, but the primary driver for me is an app doing vector queries via sqlite-vss which needs both vector0 and vss0 libs loaded on the connection.

With this change, adding the below in a phoenix app makes everything Just Work™:

config :exqlite,
  load_extensions: [
    "./priv/sqlite/darwin-arm64/lines0",
    "./priv/sqlite/darwin-arm64/vector0",
    "./priv/sqlite/darwin-arm64/vss0"
  ]

If there's interest in this, I'm happy to clean up the PR (coughIO.puts...cough) and update with documentation as well, but didn't want to invest too much time without confirming it's a change you want to take upstream.

[warmwaffles]

This does introduce loading extensions globally for anyone using multiple ecto sqlite databases. While I think 90+% of use cases just have one DB, I think there will be others out there that need different extensions loaded for different repos.

This is contrived but I was thinking something like:

config :my_app, MyApp.FooRepo,
  database: "foo.db",
  load_extensions: [
    "./priv/sqlite/darwin-arm64/lines0"
  ]

config :my_app, MyApp.BarRepo,
  database: "bar.db",
  load_extensions: [
    "./priv/sqlite/darwin-arm64/vector0",
    "./priv/sqlite/darwin-arm64/vss0"
  ]

Having it at the global level for exqlite is good to have, but allowing it to be loaded on a per repo basis would be another configuration we could support.

[bkono]

This does introduce loading extensions globally for anyone using multiple ecto sqlite databases. While I think 90+% of use cases just have one DB, I think there will be others out there that need different extensions loaded for different repos.
....
Having it at the global level for exqlite is good to have, but allowing it to be loaded on a per repo basis would be another configuration we could support.

Great suggestion. I've gone ahead and updated to support a combined global and per-connection options loading. Let me know if you have any codebase style preferences like extracting the case into separate do_load_extensions funs disregard, credo was unhappy with that extra nest so I extracted it

[warmwaffles]

Perfect!

[warmwaffles]

@bkono would you mind adding some documentation to the Exqlite.Connection.connect/1 function? Once that's in place we should be ready to merge and release.

[bkono]

@bkono would you mind adding some documentation to the Exqlite.Connection.connect/1 function? Once that's in place we should be ready to merge and release.

Of course.

In my apps I've been using a little helper for architecture resolution (since I'm on macOS & linux for dev & deploy). Wasn't sure if there's a good place to suggest something like this. I'll probably just create a light sample repo to point people at, but adding it here in case you have an alternative:

arch_dir =
  System.cmd("uname", ["-sm"])
  |> elem(0)
  |> String.trim()
  |> String.replace(" ", "-")
  |> String.downcase()

config :myapp, arch_dir: arch_dir

config :myapp, Myapp.Repo,
  load_extensions: [
    "./priv/sqlite/#{arch_dir}/vector0",
    "./priv/sqlite/#{arch_dir}/vss0"
  ]

[warmwaffles]

In my apps I've been using a little helper for architecture resolution (since I'm on macOS & linux for dev & deploy). Wasn't sure if there's a good place to suggest something like this. I'll probably just create a light sample repo to point people at, but adding it here in case you have an alternative:

I think that is a totally reasonable example to provide. Others may do their resolutions differently.

[bkono]

In my apps I've been using a little helper for architecture resolution (since I'm on macOS & linux for dev & deploy). Wasn't sure if there's a good place to suggest something like this. I'll probably just create a light sample repo to point people at, but adding it here in case you have an alternative:

I think that is a totally reasonable example to provide. Others may do their resolutions differently.

Done and updated. Let me know if there's anything else missing.