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UUID Use Case

UUID Placeholder ID

Sometimes you need an id before the row is created — a draft, a preview, a template. A UUID placeholder fills the gap.

Pre-entitySchema-validv4

Version

How many

Uppercase Hyphens Braces { }

Result

Generated locally with the Web Crypto API — nothing leaves your browser.

What Is UUID Placeholder ID?

A placeholder UUID lets a form or preview render with a valid id before persisting, then be replaced on save.
It avoids magic values like 0 or -1 that break type checks and uniqueness.

How to generate

Generate a v4 UUID when creating a draft.
Use it as the temporary id in the UI.
Replace with the persisted id on save.

Use Cases

Draft editors.
Preview rendering.
Template instantiation.

Code Examples

JavaScript

const id = crypto.randomUUID();

Python

import uuid
id = uuid.uuid4()

Frequently Asked Questions

Keep the placeholder after save?

No — swap it for the real, persisted id; the placeholder was only to keep the shape valid.

Why not a sentinel like -1?

Sentinels break 'id is a valid UUID' assumptions and can collide in maps.

Related tools

UUID v1 Generator UUID v3 Generator UUID v4 Generator UUID v5 Generator UUID v6 Generator UUID v7 Generator UUID v8 Generator Bulk UUID Generator Short UUID Generator UUID Validator UUID Formatter UUID as a Primary Key UUID Database ID UUID Foreign Key UUID Shard Key UUID Partition Key UUID in a Composite Key UUID Surrogate Key UUID API Key UUID Session Token UUID Access Token UUID Refresh Token UUID Idempotency Key UUID Request ID UUID Correlation ID UUID Trace ID UUID CSRF Token UUID Nonce UUID Filename UUID Object Key UUID S3 Key UUID Upload ID UUID Cache Key UUID Blob Name UUID Temp File UUID User ID UUID Account ID UUID Customer ID UUID Device ID UUID Tenant ID UUID Client ID UUID Anonymous ID UUID Member ID UUID Message ID UUID Event ID UUID Job ID UUID Task ID UUID Queue Message ID UUID Transaction ID UUID Order ID UUID Invoice ID UUID Payment ID UUID Reset Token UUID Verification Token UUID Invite Code UUID API Secret UUID Share Link UUID Magic Link UUID Node ID UUID Worker ID UUID Lock ID UUID Cluster ID UUID Test Data UUID Seed Data UUID Fixture UUID Mock ID UUID Placeholder ID UUID Sample ID