Generators Overview

DataGeneration includes 18 built-in generators for creating realistic test data.

Data Generators

Generate realistic domain-specific data:

Generator	Description	Example Output
UUID	UUID v4 strings	550e8400-e29b-41d4-a716-446655440000
Name	Names and titles	John Doe, Dr., Smith
Internet	Email, URLs, domains	john@example.com, https://example.com
Address	Addresses and locations	123 Main St, New York, 10001
Company	Company names and industries	Acme Corp, Technology
Country	Countries and codes	United States, US, USD
Book	Book titles, authors, genres	The Great Gatsby, F. Scott Fitzgerald
Finance	IBAN, BIC, credit cards	DE89370400440532013000, DEUTDEFF
Phone	Phone numbers	+1-555-123-4567

Primitive Generators

Generate basic data types:

Generator	Description	Options
Number	Random integers	min, max
Float	Floating-point numbers	min, max, decimals
Boolean	True/false values	probability
String	Random strings	length, allowedChars, regex
Date	Dates and timestamps	from, to, format

Utility Generators

Special-purpose generators:

Generator	Description	Use Case
Lorem	Lorem ipsum text	Placeholder content
Sequence	Auto-incrementing numbers	IDs, counters
Choice	Pick from options	Enums, statuses
CSV	Read from CSV files	External data

Usage Patterns

Basic Generator

{
  "id": {"gen": "uuid"},
  "name": {"gen": "name.fullName"}
}

Generator with Options

{
  "age": {"gen": "number", "min": 18, "max": 65},
  "price": {"gen": "float", "min": 9.99, "max": 999.99, "decimals": 2}
}

Accessing Sub-fields

Some generators return objects with multiple fields:

{
  "firstName": {"gen": "name.firstName"},
  "lastName": {"gen": "name.lastName"},
  "fullName": {"gen": "name.fullName"}
}

Weighted Choices

{
  "priority": {
    "gen": "choice",
    "options": ["low", "medium", "high", "critical"],
    "weights": [50, 30, 15, 5]
  }
}

Custom Generators

You can create custom generators by implementing the Generator interface:

public class CustomGenerator implements Generator {
    @Override
    public JsonNode generate(GeneratorContext context) {
        // Your generation logic
        return context.mapper().valueToTree("custom value");
    }
}

// Register it
DslDataGenerator.create()
    .withCustomGenerator("custom", new CustomGenerator())
    .fromJsonString(dsl)
    .generate();

Then use it in your DSL:

{
  "customField": {"gen": "custom"}
}

Generator Compatibility

Filtering Support

Only the Boolean generator currently supports filtering:

{
  "isActive": {
    "gen": "boolean",
    "probability": 0.8,
    "filter": [false]  // Only generate true values
  }
}

For other generators, use the Choice generator with filtering:

{
  "status": {
    "gen": "choice",
    "options": ["active", "inactive", "banned"],
    "filter": ["banned"]
  }
}

Sequential Support

Generators that support sequential access:

• Sequence - Built-in sequential behavior
• CSV - Can read sequentially with "sequential": true
• Choice - Can cycle through options sequentially

Next Steps

• Explore individual generator documentation
• Learn about References
• See Common Patterns