Schema Migration and Development Seed Evolve additively, generate safely, seed the minimum relational graph
Phase 11 - Persistent Task CRUD API Volume 03 - Database Engineering
Architecture milestone Phase 09 learning schema
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Phase 11 replaces process memory with durable PostgreSQL-backed application behavior.
STEP 1 - Evolve the Prisma schema safely Phase 09 created a small Todo table for learning. Phase 10 designed the real TaskFlow domain. A production-minded migration should prefer additive change over casually dropping a table that might contain useful data.
Keep the old PostgreSQL table for now by mapping it to a clearly named LegacyTodo model. Add the new User, Workspace, Membership, Project, and Task models in the same schema. Retire legacy data only after an explicit cleanup/migration decision.
model LegacyTodo { id String @id @default(cuid()) title String completed Boolean @default(false) createdAt DateTime @default(now()) updatedAt DateTime @updatedAt
@@map("Todo")
}The Prisma model name changes for application clarity, while @@map("Todo") preserves the existing database table name. The new TaskFlow models are then added beside it.
Run schema checks before migration From taskflow\apps\api run:
pnpm exec prisma format
pnpm exec prisma validateValidation should succeed before Prisma touches the database. If it does not, stop here. Migration output is not the place to discover a malformed schema.
Create the domain migration pnpm exec prisma migrate dev --name add_taskflow_domain
Open the generated migration.sql before treating the migration as complete. Confirm that the migration creates the TaskFlow tables and does not unexpectedly DROP the learning Todo table.
Regenerate the client The generated Prisma Client is derived from schema.prisma. New models are not available to TypeScript until the client is regenerated.
pnpm exec prisma generate
pnpm run buildschema.prisma
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migrate dev
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prisma generate
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generated Prisma Client
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Database structure and TypeScript client code are related, but they are not the same artifact.
STEP 2 - Seed the minimum relational graph A Task requires projectId, and a Project requires a Workspace. Rather than weakening those relations for convenience, Phase 11 creates a tiny development graph that satisfies the real model.
Workspace -> Membership <- User -> Project -> Task
The included prisma/seed.ts is idempotent for the learning Workspace/User/Membership. It finds or creates the Learning Project, then prints the Project ID needed by POST /tasks.
pnpm exec ts-node prisma/seed.tsTaskFlow development seed ready. Copy the printed Project ID. You will use it as projectId in the first POST request.
Prisma improves developer ergonomics, but migrations and generated queries still change a real relational database. You should be able to inspect both sides.
Restate the goal of “Schema Migration and Development Seed” as one observable behavior. Write the success signal before touching code.
Trace the boundary map: domain intent → Prisma Client → generated SQL → PostgreSQL → mapped result. Mark the one boundary this lesson changes.
Inspect the current repository state and record the exact files, route, table, or runtime involved. Avoid creating an abstraction before you can name the existing owner.
Implement the smallest vertical slice. Add one coherent change, run the narrowest verification command, and read the output before continuing.
Connect the slice to TaskFlow’s phase artifact: Working /tasks API supporting create/list/read/update/delete against PostgreSQL with consistent error behavior.. Verify behavior from the outside as a user or API client would.
Create one controlled failure that is safe to reproduce. Predict the symptom first, capture evidence, locate the earliest broken boundary, then fix only that cause.
Close the reference and rebuild or explain the core change from memory. Record what you would monitor or test before trusting the same change in production.
const tasks = await prisma.task.findMany({
where: { workspaceId },
orderBy: [{ createdAt: "desc" }, { id: "desc" }],
take: 20,
});Do not copy this as a finished answer. Predict what each boundary does, type the smallest useful slice, run it, then compare the result with your prediction.
Verify connection string, host, port, SSL/pooler mode, network reachability, and which environment file the process loaded.
Read the generated SQL before applying it and compare the change against existing production-shaped data.
Without copying the final source, create a second small scenario that applies “Schema Migration and Development Seed” to a different TaskFlow resource or input. Write the acceptance criteria first, implement it, and provide the evidence that each criterion is satisfied.
Implement create through the service and verify both HTTP response and database row.
Use the smallest change that demonstrates this lesson. Stop after it works and capture evidence.PATCH treats omitted values as null/empty
Predict the symptom before causing the failure. Then locate the earliest boundary where reality diverges from expectation.Why does this responsibility live here, what input does it trust, what output proves success, and what would go wrong if another layer owned it?
If your explanation is vague, repeat the boundary trace before moving on.Close the reference. Reproduce the core idea from memory or explain the exact request/data flow aloud. Then check your diff or notes for accidental shortcuts that bypass validation, authorization, error handling, or verification earned in earlier phases.