Phase 6: Building With Real Data · 20 min · Any vibe coding tool · Supabase

From Mock Data to Real Databases

Mock data is a prototype tool, not a product. Know when to graduate to a real database.

Hiring signal: What changes when you use this: you know when and how to transition from mock data to a real database — which means your apps can actually persist and share data.

What you will learn

Understand why mock data is useful for prototyping but insufficient for production
Know the transition path: mock data → localStorage → real database
Recognize when to make the transition (not too early, not too late)
Understand what changes when you switch to a real database

Your Mission

Identify your app's current data stage and plan the transition to the next stage. Output: transition_plan.md.

You need: A project you've built with AI (any tool).

Time: 20 minutes.

Step 1: Learn the Three Stages of Data (5 min)

Stage 1: Mock Data (Prototype)

const habits = [
  { id: 1, name: 'Drink water', streak: 5, completed: true },
  { id: 2, name: 'Exercise', streak: 3, completed: false },
]

Hardcoded in code. Same data every time. Good for: prototyping UI, testing layouts. Limitations: no persistence, can't add/edit/delete for real.

Stage 2: LocalStorage (Prototype+)

const habits = JSON.parse(localStorage.getItem('habits') || '[]')
localStorage.setItem('habits', JSON.stringify(habits))

Stored in browser. Persists across refreshes. Good for: single-user apps, personal tools. Limitations: device-specific, no multi-user, ~5MB limit.

Stage 3: Real Database (Production)

const { data, error } = await supabase.from('habits').select('*')

Stored on server. Good for: production, multi-user, cross-device sync. Limitations: requires setup, auth, async patterns, error handling.

Don't skip to Stage 3 too early
A common mistake: jumping straight to a real database before the UI is stable. Build with mock data first. Get the UI right. Then localStorage to test persistence. Then a real database when you need multi-user or cross-device. Each stage adds complexity — only add it when you need it.

Unlock the full lesson

You've read the first 2 sections. The rest of this lesson covers Step 2: Identify Your Current Stage (3 min), Current Stage, Step 3: Plan the Transition (7 min), Next Stage: [stage name], Step 4: Make the Decision (5 min), Decision: [Transition now / Stay at current stage], Reasoning, If Transitioning — Spec for the AI, You're Done — plus a hands-on lab, quiz, and project artifact.

Create a free account to unlock Phase 0 and Phase 1 of every course — no credit card.

Related lessons

Setting Up Supabase
Authentication Patterns
Environment Variables and Secrets
Data Patterns That Don't Break Production

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