required : Array<String>

required

Array<String>

An object instance is valid against this keyword if every item in the array is the name of a property in the instance.

Value	This keyword must be set to a non-empty array of unique strings Hint: Use the `jsonschema metaschema` and `jsonschema lint` commands to catch keywords set to invalid values
Kind	Assertion
Applies To	Object
Base Dialect	Draft 4
Changed In	None
Introduced In	Draft 3
Vocabulary	Validation
Specification	https://json-schema.org/draft-04/draft-fge-json-schema-validation-00#rfc.section.5.4.3
Metaschema	http://json-schema.org/draft-04/schema#
Official Tests	draft4/required.json
Default	As if it was set to the (invalid) value: `[]`
Annotation	None
Affected By	None
Affects	None
Also See	dependencies (Vocabulary: Validation) maxProperties (Vocabulary: Validation) minProperties (Vocabulary: Validation)

The required keyword restricts object instances to define the given set of properties.

Common Pitfall

The presence of this keyword does not depend on the presence of the properties keyword. The required keyword mandates that certain properties are present (independently of their value), while the properties keyword describes the value of such properties when present.

Remember that JSON Schema is a constraint-driven language. Therefore, non-object instances successfully validate against this keyword. If needed, make use of the type keyword to constraint the accepted type accordingly.

Examples

A schema that constrains object instances to define certain properties Schema

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "required": [ "foo", "bar", "baz" ]
}

Valid An object value that defines the required properties to any values is valid Instance

{ "foo": 1, "bar": 2, "baz": 3 }

Valid An object value that defines a superset of the required properties is valid Instance

{ "foo": 1, "bar": 2, "baz": 3, "extra": true }

Invalid An object value that only defines a subset of the required properties is invalid Instance

{ "foo": 1, "bar": 2, "extra": true }

Invalid An empty object is invalid Instance

{}

Valid A non-object value is valid Instance

"Hello World"

A schema that constrains object instances to define certain properties and to describe their value Schema

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "required": [ "name", "age" ],
  "properties": {
    "name": { "type": "string" },
    "age": { "type": "integer" }
  }
}

Valid An object value that defines the required properties and matches their definition is valid Instance

{ "name": "John Doe", "age": 30 }

Valid An object value that defines a superset of the required properties and matches their definition is valid Instance

{ "name": "John Doe", "age": 30, "extra": true }

Invalid An object value that only defines a subset of the required properties and matches their definition is invalid Instance

{ "name": "John Doe" }

Invalid An object value that defines the required properties but does not match their definition is invalid Instance

{ "name": 123, "age": "foo" }