JSON Schema

rngo aims to support all keywords in the 2020-12 draft of JSON Schema that are applicable to data generation, but for now, only a subset are supported.

See the Streams reference and the tutorial for how JSON Schema is used to define a simulation.

Custom Vocabulary

rngo extends JSON Schema with a custom vocabulary to support the generation of realistic data. All extension keywords are nested under the rngo keyword and do not change the validation semantics of the schema.

rngo.value

The rngo.value keyword specifies an expression that returns either a Set or a single Value. For example:

type: object
properties:
  name:
    type: string
    rngo:
      value: data.person.fullName

In this case, a value will be randomly selected from the data.person.fullName set when generating a value for the name property.

Upon stream creation or update, rngo will validate that all rngo.value expressions returns a value or set of the correct type.

See Expressions for more information.

rngo.probability.type

When a schema has multiple type references, you can specify the probability that each type will be generated with the rngo.probability.type keyword.

The most common scenario for this is to make a value nullable:

type:
  - integer
  - null
rngo:
  probability:
    type:
      integer: 4
      null: 1

The keyword expects a map from the type name to a weight. So, the above defines a schema that produces an integer 80% of the time and null 20% of the time.

Weights must be positive integers. By default, each type has a weight of 1.

rngo.probability.properties

For object schemas, you can specify that a likelihood that a non-required property will be included in the generated value via the rngo.probability.properties keyword:

type: object
properties:
  id:
    type: integer
  name:
    type: string
  homepage:
    type: string
required:
  - id
rngo:
  probability:
    properties:
      name: 0.9
      homepage: 0.5

The keyword expects a map from a property name to a probability between 0 and 1. So, the above schema will produce an object with a name property 90% of the time and a homepage property 50% of the time.

By default, a non-required property has a 60% chance of being included. A required property may not be referenced by rngo.probability.properties.

format Keyword

rngo supports the format keyword for string schemas, including all built-in formats from the JSON Scheme specification (eventually), along with many custom options.

Date / Time

IDs

Internet

Keyword Support