Chapter

07 · TypeScript + Prisma

Prisma models storage; TypeScript models intent. Keep them related but distinct.

Mental Model

Prisma schema = DB truth. TypeScript types = app contracts.
Do not leak Prisma client types as public API; define app-facing types.
Relations and seeds reflect reality; types express usage.

File Classification

Layer: Data modeling

Runtime: Build / server

Prisma: ✅ In schema/actions

App types: ✅ In types/

JSX: ❌ Never

Cross-entity imports: ❌ Avoid

Canonical Example (Types vs Prisma)

// prisma/schema.prisma

model Project {

  id        String   @id @default(cuid())

  name      String

  createdAt DateTime @default(now())

}


// app/(index)/projects/types/index.ts

export type Project = {

  id: string;

  name: string;

};

Quick Rules

Prisma types stay near actions; app types live in types/.
Use Pick/Omit/Partial on app types, not Prisma client types.
Seeds mirror real relations; db push for proto, migrate for prod.