Hands-On Lab & Phase Exit Move from tutorial form code to independent form architecture decisions
Phase 21 - Forms with React Hook Form + Zod Volume 06 - Professional Frontend
Hands-on lab Implement the complete create/edit Task form flow in the course repository. Do the work in small checkpoints; do not paste the final reference snapshot first.
Level 1 - Follow Install the locked packages, create the shared validators package, add the Task form schema, render accessible title/description/priority/due-date fields, and verify client validation.
Level 2 - Modify Add a character counter for description that does not replace the server-side maximum-length rule. Add a clear due-date button that sets the form value to an empty string and maps to null on submit.
Level 3 - Implement Build the Edit Task page. It must load server data, initialize the form, disable Save while unchanged, preserve input after a 409 failure, and reset dirty state after a successful save.
Level 4 - Engineer Design a reusable form architecture for an HRIS leave request with leave type, start/end dates, half-day option and reason. Identify which rules belong in: shared Zod primitives, web form schema, NestJS transport validation, service business rules, and PostgreSQL constraints.
Phase exit oral exam Question You should be able to explain
Why validate twice? Browser UX vs untrusted API boundary
Why can form schema differ from DTO? UI controls and HTTP transport have different shapes
What does isDirty mean? Current values differ from current defaults
When use Controller? Controlled/custom component needs an adapter
Why preserve values on failure? Server rejection should not destroy user work
Why not put form state in TanStack Form state is local transient editing state Query?
Phase 21 is complete when a user can create and edit a Task with accessible validation, secure authenticated submission, clear pending/error behavior, and the server remains authoritative for validation and business rules.
Hands On Lab and Phase Exit matters because it changes a real boundary in TaskFlow. The goal is to understand the inputs, owner, observable output, and failure modes before adding more abstraction.
Restate the goal of “Hands On Lab and Phase Exit” as one observable behavior. Write the success signal before touching code.
Trace the boundary map: user input → form state → Zod validation → mutation → server feedback. 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: Create/edit task forms with shared field rules, accessible errors, async submission, server-error mapping, and reset 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 form = useForm<CreateTaskInput>({
resolver: zodResolver(CreateTaskSchema),
defaultValues: { title: "", priority: "MEDIUM" },
});
const onSubmit = form.handleSubmit(values => mutate(values));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.
Return to the nearest observable boundary: input, network, process log, database, or rendered UI. Compare actual evidence with the predicted path.
Change one variable at a time and reproduce the original failure after the fix; otherwise you have correlation, not diagnosis.
Without copying the final source, create a second small scenario that applies “Hands On Lab and Phase Exit” to a different TaskFlow resource or input. Write the acceptance criteria first, implement it, and provide the evidence that each criterion is satisfied.
Implement edit/reset/cancel semantics and test what happens when server data changes while a form is open.
Use the smallest change that demonstrates this lesson. Stop after it works and capture evidence.Showing only generic toast instead of actionable field errors
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.