Multiple databases

A Worker can bind several D1 databases. Each gets its own schema file and base class, and each Model queries the database its base class names.

Binding the databases

Add each database to your Wrangler config, with its own migrations_dir:

{
  "d1_databases": [
    { "binding": "DB", "database_name": "my-app-db", "database_id": "…" },
    {
      "binding": "LOGS",
      "database_name": "my-app-logs",
      "database_id": "…",
      "migrations_dir": "logs-migrations",
    },
  ],
}

Wrangler applies a folder’s migrations to one database, so each needs its own folder.

Generating a schema for each

Generate the schemas as usual:

npx d1-record schema

With several databases, it writes one of each per binding:

Binding	Schema	Base class
DB	src/db/DB.ts	DbRecord, in src/models/db-record.ts
LOGS	src/db/LOGS.ts	LogsRecord, in src/models/logs-record.ts

Each base class names its binding, so its Models query that database:

import { LogsRecord } from "./logs-record";

export class Entry extends LogsRecord("entries") {}

await Entry.where({ level: "error" }).count(); // on LOGS

Generating Models for one database

Name the binding with --database:

npx d1-record g model Entry 'level:string!' message --database LOGS
npx wrangler d1 migrations apply my-app-logs --local

Opening several for a request

To open a request’s databases with a Session or onQuery, pass them all to withDatabase. Each Model uses the one on its binding:

import { connect, withDatabase, type Database } from "@forestfuture/d1-record";

const databases: Database[] = [connect(env.DB, { session: "first-primary" }), connect(env.LOGS)];
return withDatabase(databases, handle); // each Model uses the one on its binding

TIP

A batch writes to one database, so entries from two databases throw IncompatibleRelation.