Kysely and Deno & MySQL Driver

[mrtornado]

Anybody already written a MySQL driver to work with Kysely in Deno ? Or is that even needed anymore ? Sry my programming skills are bad and I can't write it for myself :)

[mrtornado]

I managed to create one with the help of chatgpt :) for anybody who needs something like this here it goes. I don't know how good it is, but it's working for me :

https://pastecode.io/s/mgadtzi2

[koskimas]

That seems to be created from the SQLite driver, which has a single connection. Having the mutex there forces your MySQL driver to only have one connection, which will lead to bad performance once you have more than one concurrent request running.

[mrtornado]

thanks for the info, I will try to remove it.

[mrtornado]

I managed to modify it to use a connection pool, that currently has 10 max connections, but you can modify the maxConnections: number = 10 value according to your needs and server capacity.

https://pastecode.io/s/jwfpktky

Is this one better @koskimas ?

[y12studio]

After conducting a small test, I have found that the latest version of Deno already supports npm packages like kysely and mysql2.

#!/bin/bash
TEMP_YAML="$(mktemp)"
cat <<'EOF' > $TEMP_YAML
version: "3.8"
services:
  mysql404:
    image: 'mysql:5.7'
    ports:
      - '3306:3306'
    environment:
      MYSQL_ROOT_PASSWORD: root_pass
      MYSQL_DATABASE: test_db
    command: ['--character-set-server=utf8']
  deno404:
    image: denoland/deno:alpine-1.30.3
    command:
      - /bin/sh
      - -c
      - |
        env
        sleep 10
        deno run -A - <<EOOF
        import { createPool } from "npm:mysql2";
        import { Generated, Kysely, MysqlDialect } from "npm:kysely";
        import { assertEquals } from "https://deno.land/std@0.179.0/testing/asserts.ts";
        const mysqlDialect = new MysqlDialect({
          pool: createPool({
            database: "test_db",
            host: "mysql404",
            password: "root_pass",
            user: "root",
          }),
        });

        type Person = {
          id: Generated<number>;
          first_name: string;
          last_name: string;
        };

        type Database = {
          person: Person;
        };

        const db = new Kysely<Database>({
          dialect: mysqlDialect,
        });

        await db.schema.createTable("person")
        .addColumn("id", "integer", (col) => col.autoIncrement().primaryKey())
        .addColumn("first_name", "varchar(50)", (col) => col.notNull())
        .addColumn("last_name", "varchar(50)").execute();

        await db.insertInto("person").values({first_name: 'Foo404', last_name: 'Bar'}).execute()
        const result = await db.selectFrom("person").select('first_name').execute()
        console.log("RESULT===>",result)
        assertEquals(result[0], { first_name: "Foo404"})
        EOOF
EOF

function handler() 
{
  echo "remove containers and exit"
  docker compose -f $TEMP_YAML rm -sf
  rm $TEMP_YAML
  exit 1
}

trap 'handler' SIGINT
docker compose -f $TEMP_YAML up

[mrtornado]

thanks for looking into it @y12studio but I prefer my method more, seems more cleaner.

[waptik]

I'd also like to add that npm specifiers are not yet supported on deno deploy so the npm packages will not work there unless using cdns or esm.sh. So custom adapters/dialects for deno are the way to go for now for both mysql and postgres.

[alexgleason]

I would love if I could just use kysely's query builder, target a particular dialect and then get a string. I want to pass the string to the database interface myself.

[igalklebanov]

@alexgleason https://kysely.dev/docs/recipes/splitting-build-compile-and-execute-code