Phase 27 · Lesson 03

Attachment Data Model and Prisma Migration

≈ 2 min core reading · 149 source/companion words

Learning contract

What you should be able to do after this

Explain Attachment Data Model and Prisma Migration without relying on framework buzzwords.
Connect the lesson to the phase outcome: Design a secure file-upload pipeline with storage objects, metadata, validation, signed access, lifecycle cleanup, and authorization.
Reproduce the relevant behavior and verify it with evidence.
Diagnose at least one representative failure instead of guessing.

Figure 27.3 — TaskFlow boundary map

upload intent

API authorization/validation

signed upload or storage request

object store

finalize metadata

signed/read access

This lesson belongs to Phase 27. Keep the full request/data path visible even when today's code changes only one box.

Instructor workflow: predict first → implement the smallest slice → run it → inspect evidence → break one assumption → diagnose → explain it back. Do not copy the whole code block before understanding the first failing boundary.

Attachment Data Model and Prisma Migration TaskFlow - Full Stack Developer 2026

Domain model enum AttachmentStatus { PENDING READY DELETING }

model TaskAttachment { id String @id @default(uuid()) taskId String uploadedById String bucket String @default("task-attachments") objectPath String @unique originalName String mimeType String sizeBytes Int status AttachmentStatus @default(PENDING) createdAt DateTime @default(now()) readyAt DateTime?

task Task @relation(fields: [taskId], references: [id], onDelete: Cascade) uploadedBy User @relation(fields: [uploadedById], references: [id], onDelete: Restrict)

Code

@@index([taskId, status, createdAt])
@@index([uploadedById])
}

Why metadata belongs here • Task ownership and authorization need relational joins.

• Original display filename must survive even though the object path is randomized.

• PENDING/READY/DELETING are application workflow states, not Storage object states.

• Audit/reporting can reference uploader, Task and timestamps without scanning a bucket.

Migration note Add the model and Task/User relations using the same Prisma 7.9.1 migration workflow from Phase 09. Do not hand-edit the Storage schema.

Executable lesson studio · prisma

Now turn the explanation into engineering skill.

Prisma improves developer ergonomics, but migrations and generated queries still change a real relational database. You should be able to inspect both sides.

By the end, you should be able to

Explain Attachment Data Model and Prisma Migration in terms of concrete inputs, ownership, outputs, and evidence.
Implement or reproduce the smallest TaskFlow slice that demonstrates this prisma concept.
Diagnose one representative prisma failure using observable evidence instead of trial-and-error.

Figure 27.3B — Mental model

domain intent

Prisma Client

generated SQL

PostgreSQL

mapped result

Read left-to-right while implementing. When debugging, walk right-to-left until the first observed fact differs from your prediction.

Code-along sequence

One coherent change at a time

01
Restate the goal of “Attachment Data Model and Prisma Migration” as one observable behavior. Write the success signal before touching code.
02
Trace the boundary map: domain intent → Prisma Client → generated SQL → PostgreSQL → mapped result. Mark the one boundary this lesson changes.
03
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.
04
Implement the smallest vertical slice. Add one coherent change, run the narrowest verification command, and read the output before continuing.
05
Connect the slice to TaskFlow’s phase artifact: Task attachment upload/download/delete workflow using Supabase Storage plus application metadata.. Verify behavior from the outside as a user or API client would.
06
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.
07
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.

tsKeep the generated client visible in the mental model

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.

Verification

Prove the happy path

Run the narrowest relevant command or request and require a clean exit/status.
Inspect the boundary-specific evidence: terminal output, Network panel, database row/query plan, test report, container health, or deployment logs.
Repeat the behavior once after the change so a one-off cached or stale result cannot masquerade as success.

Break it on purpose

Build debugging memory

User-controlled storage path enabling cross-tenant overwrite
Change one assumption in the prisma example—identity, input, configuration, ordering, connectivity, or state—and predict the exact symptom before running it.

SymptomInvestigation path

P1001 / connection failure

Verify connection string, host, port, SSL/pooler mode, network reachability, and which environment file the process loaded.

Migration surprises

Read the generated SQL before applying it and compare the change against existing production-shaped data.

Closed-reference challenge

Can you transfer the idea?

Without copying the final source, create a second small scenario that applies “Attachment Data Model and Prisma Migration” to a different TaskFlow resource or input. Write the acceptance criteria first, implement it, and provide the evidence that each criterion is satisfied.

Explain-back

Answer these without reopening the solution

What problem does Attachment Data Model and Prisma Migration solve in TaskFlow, and what would be observably wrong without it?
Which part of the prisma boundary owns the decision, and which neighboring layer must not own it?
What evidence proves the happy path instead of merely suggesting it worked?
Name one realistic failure or abuse case and the first place you would inspect.
If requirements doubled tomorrow, which part of this design should stay stable and which part is allowed to change?

Lesson studio

Turn the reading into skill

Do it

Upload bytes directly to storage where appropriate rather than proxying large files through the API by default.

Use the smallest change that demonstrates this lesson. Stop after it works and capture evidence.

Break it safely

User-controlled storage path enabling cross-tenant overwrite

Predict the symptom before causing the failure. Then locate the earliest boundary where reality diverges from expectation.

Explain it back

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.

Exit ticket

Before marking complete

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.

← Signed Upload Intent Architecture Private Bucket Configuration and Server Storage Client →