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UUID Generator

Generates UUID v4 (Universally Unique Identifier) strings.

Basic Usage​

{
  "id": {"gen": "uuid"}
}

Output: "550e8400-e29b-41d4-a716-446655440000"

Options​

This generator has no options.

Characteristics​

  • Format: UUID v4 (random)
  • Deterministic: Yes, when using a seed
  • Uniqueness: Extremely high probability of uniqueness
  • Length: Always 36 characters (including hyphens)

Examples​

Basic ID Field​

{
  "users": {
    "count": 5,
    "item": {
      "id": {"gen": "uuid"},
      "name": {"gen": "name.fullName"}
    }
  }
}

Multiple UUID Fields​

{
  "orders": {
    "count": 10,
    "item": {
      "id": {"gen": "uuid"},
      "transactionId": {"gen": "uuid"},
      "sessionId": {"gen": "uuid"}
    }
  }
}

With References​

{
  "users": {
    "count": 5,
    "item": {
      "id": {"gen": "uuid"}
    }
  },
  "orders": {
    "count": 20,
    "item": {
      "id": {"gen": "uuid"},
      "userId": {"ref": "users[*].id"}
    }
  }
}

Reproducibility​

When using a seed, UUIDs are deterministic:

Generation gen1 = DslDataGenerator.create()
    .withSeed(123L)
    .fromJsonString(dsl)
    .generate();

Generation gen2 = DslDataGenerator.create()
    .withSeed(123L)
    .fromJsonString(dsl)
    .generate();

// Both generations produce identical UUIDs

Common Use Cases​

  • Primary Keys: Database primary keys
  • Transaction IDs: Unique transaction identifiers
  • Session IDs: User session tracking
  • Request IDs: API request tracking
  • Correlation IDs: Distributed system tracing

Best Practices​

  1. Use for IDs: Perfect for primary and foreign keys
  2. Seed for Tests: Use seeds in tests for reproducible IDs
  3. Reference Pattern: Generate UUIDs in parent collections, reference in children
  4. Avoid Duplication: Don't worry about collisions - UUID v4 is designed for uniqueness

SQL Output​

generation.streamSqlInserts("users").forEach(System.out::println);

Output:

INSERT INTO users (id, name) VALUES ('550e8400-e29b-41d4-a716-446655440000', 'John Doe');

Next Steps​