Prisma 7 and Prisma 8 Side by Side

This repository will demonstrate how to run Prisma 7 and Prisma 8 side by side. The README will document each step of that journey as the example evolves.

Initial state

The repository began with a single REST API running only Prisma 7. Prisma 8 had not been added yet.

Stack

• Node.js with TypeScript and ESM
• Hono with @hono/node-server
• Prisma 7.10.0-dev.58
• @prisma/client and @prisma/adapter-pg at 7.10.0-dev.58
• PostgreSQL 17 running through Docker Compose
• pnpm

Prisma uses the prisma-client generator and writes the generated client to generated/prisma. The application connects through Prisma's PostgreSQL driver adapter backed by pg.

Data model

The starting schema has two related models:

• User — unique email, optional name, timestamps, and posts
• Post — title, optional content, published state, timestamps, and an author

Deleting a user cascades to their posts.

API surface

The Hono application exposes:

• GET /health
• GET /users
• POST /users
• GET /users/:id
• PATCH /users/:id
• DELETE /users/:id
• GET /posts
• POST /posts
• GET /posts/:id
• PATCH /posts/:id
• DELETE /posts/:id

Successful endpoint responses use HTTP 200. User responses include their posts, and post responses include their author.

This is the baseline from which Prisma 8 and the side-by-side configuration will be introduced.

Step 1: Namespace the Prisma 7 CLI

The direct prisma development dependency is now @prisma/prisma7 at 7.10.0-dev.58. This package exposes the prisma7 binary and keeps prisma at the same version as a transitive dependency. Giving Prisma 7 its own direct package, project-level binary, and config filename leaves the conventional project-level Prisma names available for adding Prisma 8 side by side later without ambiguity.

Concretely, this step:

• replaces the direct prisma dependency with @prisma/prisma7
• changes the generate and migration scripts to call prisma7
• renames prisma.config.ts to prisma7.config.ts
• changes the config import to @prisma/prisma7/config

Step 2: Add Prisma 8 side by side

Prisma 8 is now installed as exact prisma@8.0.0-rc.15 and @prisma/orm-postgres@8.0.0-rc.11. Its configuration and inferred database contract are separate from the Prisma 7 schema and config, and its emitted contract artifacts and PostgreSQL ORM runtime are kept separate from the generated Prisma 7 client and runtime.

The Users routes now use the Prisma 8 PostgreSQL ORM while the Posts routes continue to use Prisma 7. Both runtimes share the existing database schema and preserve the API's relations, but Prisma 7 remains the sole owner of migrations.

Final step: Transfer migration ownership to Prisma 8

Prisma 8 now owns migration planning and application. The existing database was adopted with one command, prisma db sign, which verified that the live schema matches the emitted contract, wrote Prisma 8's marker in the database, stored the contract snapshot under migrations/snapshots/, and pointed the db ref (migrations/app/refs/db.json) at it. No migration was written at this point: the next prisma migration plan starts from the signed contract, writes a baseline package that records the adopted schema, and a second package with only the change.

Future migrations use the Prisma 8 migration scripts. Prisma 7 remains only for the Posts runtime and Prisma 7 client generation; its earlier migration files are retained as journey history but no longer drive migrations.