Add support for running a command to get the database connection string in `postgrestools.jsonc`

[psteinroe]

Discussed in #292

^{Originally posted by remorses April 1, 2025}
I want to use the Supabase database directly instead of a local database, to do that you could add support for a config option dbCommand to get the database uri via stdout

{
  "$schema": "./docs/schemas/latest/schema.json",
  // get the database uri using dotenv-cli npm package
  "dbCommand": "dotenv -- bash -c 'echo $DATABASE_URL'",
  // get database uri using doppler
  "dbCommand": "doppler secrets get --plain DATABASE_URL",
}

This allows to get the database url using tools like Doppler or dotenv

[willruggiano]

I would also love the ability to use InitializeParams and/or the workspace/didChangeConfiguration notification to configure this stuff, rather than be limited to a configuration file. The latter could enable switching database connections. Both options would then allow the client to determine the db parameters however they wanted, e.g. something along the lines of (in Neovim with lspconfig);

require("lspconfig").postgres_lsp.setup {
  settings = {
    postgres_lsp = {
      db = load_from_env()
    },
  }
}

-- You could map this in on_attach, for example. Or use Telescope. Or whatever.
function switch_database_connection(client --[[@type vim.lsp.Client]])
  client.notify(
    "workspace/didChangeConfiguration",
    {
      settings = { ... as above ... }
    }
  )
end