prisma-class-generator: Instructions file for Claude Code

CLAUDE.md

Guidance for AI coding assistants (and human contributors) working in this repo. For what this package does and how to use it, see README.md — this file is about working on the generator itself. For the PR mechanics (checklist, what tends to get merged quickly), see CONTRIBUTING.md.

What this is

A Prisma generator (prisma-class-generator) that reads a schema's DMMF and emits one TypeScript class per model/composite-type, decorated for @nestjs/swagger and/or @nestjs/graphql. It runs as a subprocess Prisma's CLI spawns via the JSON-RPC generator protocol (@prisma/generator-helper's generatorHandler), not as a library the user imports.

Architecture

src/
  index.ts          generatorHandler entry point (what Prisma's CLI actually spawns)
  bin.ts             CLI entry point (the "prisma-class-generator" bin)
  generator.ts       PrismaClassGenerator — orchestrates one full run()
  convertor.ts       PrismaConvertor — DMMF.Field -> FieldComponent/ClassComponent
  components/        Class/Field/Decorator/Import/File components (string-template assembly)
  templates/         `#!{PLACEHOLDER}` string templates the components fill in

This is deliberately a string-template pipeline, not an AST transform. It's simple to reason about at this size — don't reach for ts-morph or similar without a concrete reason.

Runtime dependencies are deliberately kept to two (@prisma/generator-helper, prettier) — everything a user installs to run this generator. @prisma/internals is a devDependency on purpose: the specs use its getDMMF, but it installs 28MB and prisma itself doesn't depend on it (so it never dedupes), and the only two things the generator needed from it — parseEnvValue and logger.info — are transcribed into util.ts. Before adding any runtime import, check whether it's really worth what it costs a user; npm run verify:packed is what catches a runtime import that only resolves because this repo has everything installed.