@jumentix/database-client-factory

Compiles the correct database client implementation from environment/driver configuration.

What it is

Compiles the correct database client implementation from environment/driver configuration.

Why it exists

Services hard-coded a driver. Switching Mongo→SQL meant editing use-cases. The factory keeps selection at the composition root.

When to use: Bootstrapping a backend runtime that must pick a DB driver from env.

When not to use: Browser apps, or when you only need the port types.

Responsibility in context

• Stack layer: persistence / runtime composition
• Problem boundary it owns: buildDatabaseClientCompilers, DriverName, and related factory types.
• Used with: Works with persistence-contracts + external-* adapters.
• Typical composition: env driver → factory → client/stores → use-cases.
• Journeys: backend-template / REST guide runtime setup.
• Not responsible for: SQL query building inside use-cases or OpenAPI routing.

Prerequisites

• Bun 1.3.13+ (monorepo pin) or the Node runtime your service already uses
• Read Getting started first
• Basic TypeScript modules/import knowledge

Glossary

• Port — TypeScript contract the application depends on (no vendor types).
• Adapter — Concrete implementation that talks to a driver, broker, or protocol.
• Composition root — Process startup code that wires env → adapters → use-cases.

Numbered steps

1. Install

bun add @jumentix/database-client-factory

2. First success (under 30 min)

import { buildDatabaseClientCompilers } from '@jumentix/database-client-factory';

const compilers = buildDatabaseClientCompilers();
// Select compiler from env (e.g. DB_DRIVER=mongo) at composition root.

3. Core workflows

1. Read driver from env

Map DB_DRIVER (or project equivalent) to DriverName.

2. Compile once at boot

Do not rebuild clients per request.

3. Inject ports upward

Pass contracts to use-cases, not the factory.

4. Full practical surface (exports)

• buildDatabaseClientCompilers
• DriverName
• IDatabaseClientLike

Use exports from application/adapters layers as described above — not from domain entities.

Common errors

Verify success: the first-success snippet runs (or typechecks against your service) and your use-case depends only on ports.

Junior checklist (“I can …”)

• I can select a driver from env without touching domain code
• I know the factory is Node/backend-only

Next step

Continue with external-store-proxy.