DurableObject

Source: src/Drizzle/Cloudflare.ts

Open a Drizzle database over the current Durable Object’s SQLite storage using the drizzle-orm/effect-sqlite-do integration (driven by @effect/sql-sqlite-do’s SqliteClient), applying drizzle-kit’s generated migrations first when provided.

Every query is an Effect with a typed error channel — drizzle’s EffectDrizzleQueryError (query + params + cause, wrapping the underlying effect-sql SqlError) — so failures are handled with Effect.catchTag instead of leaking as defects. Transactions add SqlError to the union. Opening the db itself never fails: a migration that cannot apply dies, since the instance is unusable without its schema.

Yield it in the object’s inner (instance) Effect — it runs when the instance activates, before any request reaches its methods:

schema.ts

import { defineRelations } from "drizzle-orm";
import { integer, sqliteTable, text } from "drizzle-orm/sqlite-core";

export const users = sqliteTable("users", {
  id: integer("id").primaryKey({ autoIncrement: true }),
  name: text("name").notNull(),
});

export const posts = sqliteTable("posts", {
  id: integer("id").primaryKey({ autoIncrement: true }),
  userId: integer("user_id").notNull().references(() => users.id),
  title: text("title").notNull(),
});

export const relations = defineRelations({ users, posts }, (t) => ({
  users: { posts: t.many.posts() },
  posts: { author: t.one.users({ from: t.posts.userId, to: t.users.id }) },
}));

import * as Drizzle from "alchemy/Drizzle/Cloudflare";
import migrations from "./drizzle/migrations.js";
import { posts, relations, users } from "./schema.ts";

export class Users extends Cloudflare.DurableObject<Users>()(
  "Users",
  Effect.gen(function* () {
    return Effect.gen(function* () {
      const db = yield* Drizzle.DurableObject({ migrations, relations });

      return {
        addUser: (name: string) => db.insert(users).values({ name }),
        listUsers: () => db.select().from(users),
        listUsersWithPosts: () =>
          db.query.users.findMany({ with: { posts: true } }),
        // typed error handling per operation:
        tryAddUser: (name: string) =>
          db
            .insert(users)
            .values({ name })
            .pipe(
              Effect.catchTag("EffectDrizzleQueryError", () =>
                Effect.succeed(undefined),
              ),
            ),
      };
    });
  }),
) {}