Multiple subschemas

It is a common practice to validate something against multiple subschemas, and the following keywords will help you combine subschemas into one validator.

Validation keywords

The following keywords are supported by any instance type, and are evaluated in the presented order. All keywords are optional.

anyOf

An instance is valid against this keyword if is valid against at least one schema defined by the value of this keyword. The value of this keyword must be an array of valid JSON schemas (objects or booleans).

{
  "type": "array",
  "anyOf": [
    {
      "contains": {"const": 0}
    },
    {
      "contains": {"const": "ok"}
    }
  ]
}

Please pay attention when using anyOf! You could unintentionally write schemas that never validate!

{
  "type": "string",
  "anyOf": [
    {"const": 0},
    {"const": 1}
  ]
}

This schema will never validate

oneOf

An instance is valid against this keyword if is valid against exactly one schema defined by the value of this keyword. The value of this keyword must be an array of valid JSON schemas (objects or booleans).

{
  "type": "array",
  "items": {
    "type": "number"  
  },
  "oneOf": [
    {
      "items": {
        "exclusiveMinimum": 0
      }
    },
    {
      "items": {
        "exclusiveMaximum": 0
      }
    },
    {
      "items": {
        "const": 0
      }
    }
  ]
}

Please pay attention when using oneOf! You could unintentionally write schemas that never validate!

{
  "oneOf": [
    {"const": 0},
    {"enum": [0, 1, 2]}
  ]
}

This schema will never validate

allOf

An instance is valid against this keyword if is valid against all schemas defined by the value of this keyword. The value of this keyword must be an array of valid JSON schemas (objects or booleans).

{
  "allOf": [
    {"minLength": 2},
    {"pattern": "^a"}
  ]
}

Please pay attention when using allOf! You could unintentionally write schemas that never validate!

{
  "allOf": [
    {"type": "string"},
    {"type": "number"}
  ]
}

This schema will never validate