feat(postgres/sqlite): update API to be fully async

[vdice]

Updates the postgres and sqlite modules to provide a completely async, opinionated API. This breaks the previous (canary) versions of the v4 SDKs but as they hadn't yet been released, this seems a good time to do it.

TODO:

• regenerate docs
• update docs on spinframework.dev -> docs(v4): postgres and sqlite python updates spin-docs#190

Closes #146

[dicej]

Thanks!

[itowlson]

Thanks for doing this!

[itowlson]

In principle this should presumably check the returned error future? (I am not quite sure when/where SQLite would produce the error in this case!)

[dicej]

FWIW, here's what I did to make the spin-sqlite example work on an empty database, but never got around to PR'ing:

from spin_sdk import http, sqlite
from spin_sdk.http import Request, Response
from spin_sdk.sqlite import Value_Integer, Value_Text
from spin_sdk.util import collect

class HttpHandler(http.Handler):
    async def handle_request(self, request: Request) -> Response:
        with await sqlite.open_default() as db:
            _, stream, result = await db.execute(
                "CREATE TABLE IF NOT EXISTS example (id INTEGER NOT NULL PRIMARY KEY, value TEXT NOT NULL)",
                []
            )
            await collect((stream, result))

            insert = "INSERT INTO example (id, value) VALUES (?, ?) ON CONFLICT (id) DO UPDATE SET value=excluded.value"
            
            _, stream, result = await db.execute(insert, [Value_Integer(1), Value_Text("foo")])
            await collect((stream, result))
            
            _, stream, result = await db.execute(insert, [Value_Integer(2), Value_Text("bar")])
            await collect((stream, result))
            
            columns, stream, result = await db.execute("SELECT * FROM example WHERE id > (?);", [Value_Integer(1)])
            rows = await collect((stream, result))

            assert columns == ["id", "value"]
            assert len(rows) == 1
            assert isinstance(rows[0].values[0], Value_Integer)
            assert rows[0].values[0].value == 2
            assert isinstance(rows[0].values[1], Value_Text)
            assert rows[0].values[1].value == "bar"
        
        return Response(
            200,
            {"content-type": "text/plain"},
            bytes(str(rows), "utf-8")
        )

[vdice]

Thanks @dicej, I've updated the example.

[itowlson]

I believe we support both the URL form and the connection string form.

Suggested change

	The connection_string is the Postgres URL connection string.
	The connection_string is the Postgres URL or connection string.