UUID Generator in Rust — Code Examples

UUIDs (Universally Unique Identifiers) are 128-bit identifiers used as database primary keys, session tokens, and idempotency keys. UUID v4 (random) is the safe default; UUID v7 (time-ordered) is preferred for database primary keys.

Rust uses the uuid crate. Enable the v4 and v7 features in Cargo.toml for random and time-ordered UUIDs.

// Cargo.toml: uuid = { version = "1", features = ["v4", "v7"] }
use uuid::Uuid;

fn main() {
    // UUID v4 — random
    let id = Uuid::new_v4();
    println!("{}", id); // e.g. 550e8400-e29b-41d4-a716-446655440000

    // UUID v7 — time-ordered (preferred for DB primary keys)
    let id7 = Uuid::now_v7();
    println!("{}", id7);

    // Parse a UUID string
    let parsed = Uuid::parse_str("550e8400-e29b-41d4-a716-446655440000").unwrap();

    // String formatting variants
    println!("{}", parsed);              // hyphenated (default)
    println!("{}", parsed.simple());     // no dashes
    println!("{}", parsed.urn());        // urn:uuid:...
    println!("{:?}", parsed.as_bytes()); // raw [u8; 16]
}

• Enable features = ["v4"] or ["v7"] in Cargo.toml — UUID generation methods are behind feature flags.
• UUID v7 is time-sortable and reduces index fragmentation in B-tree databases — prefer it over v4 for primary keys.
• Uuid::parse_str returns a Result — use it to validate and normalise user-supplied UUID strings.

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