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Array type

Keywords for array type

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The array type is used for validating JSON indexed arrays.

{
  "type": "array"
}
Input Status
[] valid - empty array
[2, 1, "str", false, null, {}] valid
12 invalid - is integer/number
null invalid - is null
"[1, 2, 3]" invalid - is string
{"0": 1, "1": 2, "2": 3} invalid - is object

Validation keywords

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

minItems

An array is valid against this keyword, if the number of items it contains is greater than, or equal to, the value of this keyword. The value of this keyword must be a non-negative integer.

{
  "type": "array",
  "minItems": 2
}

Array must have at least 2 items.

Input Status
[1, 2, 3] valid - contains more than 2 items
["a", "b"] valid - contains 2 items
["text"] invalid - contains a single item
[] invalid - contains no items

maxItems

An array is valid against this keyword, if the number of items it contains is lower than, or equal to, the value of this keyword. The value of this keyword must be a non-negative integer.

{
  "type": "array",
  "maxItems": 2
}

Array can have at most 2 items.

Input Status
[1, 2] valid - contains 2 items
["a"] valid - contains a single item
[] valid - contains no items
[1, 2, 3] invalid - contains more than 2 items

uniqueItems

An array is valid against this keyword if an item cannot be found more than once in the array. The value of this keyword must be a boolean. If set to false the keyword validation will be ignored.

{
  "type": "array",
  "uniqueItems": true
}

Array must have unique items (for every data type).

Input Status
[1, 2, 3] valid
["a", "b", "c"] valid
[1, "1"] valid
[[1, 2], [3, 4]] valid
[1, 2, 1] invalid - duplicate 1
["a", "b", "B", "a"] invalid - duplicate a
[[1, 2], [1, 3], [1, 2]] invalid - duplicate [1, 2]
[{"a": 1, "b": 2}, {"a": 1, "c": 2}, {"a": 1, "b": 2}] invalid - duplicate {"a": 1, "b": 2}

contains

An array is valid against this keyword if at least one item is valid against the schema defined by the keyword value. The value of this keyword must be a valid json schema (object or boolean).

Please note that an empty array will never be valid against this keyword.

{
  "type": "array",
  "contains": {
    "type": "integer"
  }
}

Array must contain at least one integer.

Input Status
[1] valid
[1, 2] valid
["a", "b" -4.0] valid
[] invalid
["a", "b", "1"] invalid
[2.3, 4.5, -6.7] invalid

items

An array is valid against this keyword if items are valid against the corresponding schemas provided by the keyword value. The value of this keyword can be

  • a valid json schema (object or boolean), then every item must be valid against this schema
  • an array of valid json schemas, then each item must be valid against the schema defined at the same position (index). Items that don’t have a corresponding position (array contains 5 items and this keyword only has 3) will be considered valid, unless the additionalItems keyword is present - which will decide the validity.
{
  "type": "array",
  "items": {
    "type": "integer",
    "minimum": 0
  }
}

Array must contain only positive integers.

Input Status
[1, 2, 3] valid
[-0, 2.0] valid
[] valid
[-2, 3, 4] invalid
["a", 2] invalid 
{
  "type": "array",
  "items": [
    {"type": "integer"},
    {"type": "string"}
  ]
}

First item of the array must be an integer and the second a string. Other items can be anything.

Input Status
[1, "a"] valid
[1.0, "a", 5.6, null, true] valid
[1] valid
[] valid
["a", 1] invalid
[5.5, "a"] invalid
[5, 6] invalid

additionalItems

An array is valid against this keyword if all unchecked items are valid against the schema defined by the keyword value. An item is considered unchecked if items keyword contains an array of schemas and doesn’t have a corresponding position (index). If the items keyword is not an array, then this keyword is ignored. The value of the keyword must be a valid json schema (object, boolean).

{
  "type": "array",
  "items": [
    {"type": "integer"},
    {"type": "string"}
  ],
  "additionalItems": {
    "type": "boolean"
  }
}

First item of the array must be an integer and the second a string. Other items can only be booleans.

Input Status
[1, "a", true, false, true, true] valid
[1, "a"] valid
[1] valid
[] valid
[1, "a", 2] invalid
[1, "a", true, 2, false] invalid
[1, true, false] invalid

Keywords for object type

Object type

Default formats

Formats
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