maxItems : Integer

maxItems

Integer

An array instance is valid if its size is less than, or equal to, the value of this keyword.

Kind Assertion
Applies To Array
Dialect 2020-12
Introduced In Draft 1
Vocabulary Validation
Specification https://json-schema.org/draft/2020-12/json-schema-validation.html#section-6.4.1
Metaschema https://json-schema.org/draft/2020-12/meta/validation
Also see

The maxItems keyword is used to specify the maximum number of items allowed in an array. It can be used to define constraints on the size of an array within an array instance.

  • Applies to arrays only.
  • Value must be a non-negative integer.
  • An array is valid if it has less than or equal to the specified number of elements.
  • Omitting maxItems means the array has no upper limit (unbounded).

Examples

Schema with 'maxItems' keyword Schema 
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "array",
  "maxItems": 3
}
An array instance with 3 or less items is valid Instance 
[ 1, true, "hello" ]
An array instance with more than 3 items is invalid Instance 
[ 1, 2, "apple", "banana", true ]
Schema with the 'maxItems' and 'items' keywords Schema 
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "array",
  "items": { "type": "boolean" },
  "maxItems": 2
}
An array instance containing 2 or less items, which conform to the 'items' subschema, is valid Instance 
[ false ]
An array instance with more than 2 elements is invalid Instance 
[ false, false, true ]
Schema with the 'maxItems', 'prefixItems' and 'contains' keywords Schema 
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "array",
  "prefixItems": [
    { "type": "number" },
    { "type": "string" }
  ],
  "contains": { "type": "boolean" },
  "maxItems": 3
}
An array instance containing 3 or less items, which successfully validates against 'prefixItems' and 'contains', is valid Instance 
[ 1, "John", false ]
An array instance with more than 3 elements is invalid Instance 
[ 1, "John", "Doe", false ]
First and second items should be number and string respectively Instance 
[ "John", 1, false ]