JSON Schema

Eventvisor makes use of a subset of the JSON Schema specification when defining attribute and event schemas. Common structures can be shared through reusable Schemas.

Reusable definitions#

Store a shared definition in schemas/ and reference it from an event, attribute, property, or array item:

schema: identifier

References are resolved during linting, code generation, and datafile builds. See Reusable Schemas for complete examples.

Supported types are listed below:

string#

For simple strings (text values):

type: string

enum#

You can specify a list of allowed values for a string:

type: string
enum:
  - foo
  - bar

maxLength#

You can specify the maximum length for a string:

type: string
maxLength: 100

minLength#

You can specify the minimum length for a string:

type: string
minLength: 0

pattern#

You can specify a regular expression for a string:

type: string
pattern: ^[a-z]+$

Patterns use the same portable regular expression subset as conditions. This keeps validation consistent across SDK languages.

boolean#

For boolean (true/false) values:

type: boolean

number#

For numeric values (integer or float):

type: number

maximum#

You can specify the maximum value for a number:

type: number
maximum: 100

minimum#

You can specify the minimum value for a number:

type: number
minimum: 0

integer#

For whole numbers only:

type: integer

Similar to number, you can also specify the maximum and minimum values for an integer.

object#

Objects are strict by default. Properties not declared in properties fail validation.

For objects (key-value pairs):

type: object
properties:
  firstProperty:
    type: string
  secondProperty:
    type: number
required:
  - firstProperty

additionalProperties#

Allow undeclared properties explicitly when gradual adoption requires a looser boundary:

type: object
additionalProperties: true

The default is false. Prefer declaring known properties so Catalog, generated types, and validation describe the same contract.

Nested objects#

You can also define nested objects:

type: object
properties:
  firstProperty:
    type: string
  nested:
    type: object
    properties:
      foo:
        type: string
      bar:
        type: string
    required:
      - foo
      - bar
required:
  - firstProperty

array#

For arrays:

type: array
items:
  type: string

When inside an object:

type: object
properties:
  arrayProperty:
    type: array
    items:
      type: string
required:
  - arrayProperty

maxItems#

You can specify the maximum number of items for an array:

type: array
maxItems: 100

minItems#

You can specify the minimum number of items for an array:

type: array
minItems: 0

uniqueItems#

You can specify if the items in the array should be unique:

type: array
uniqueItems: true

Objects and arrays are compared structurally for uniqueItems, enum, and const. Property order does not change equality.

Common properties#

You can make use of the following properties for all types above:

const#

You can specify a constant value:

type: string
const: "foo"

default#

You can specify a default value:

type: string
default: "default value"