propertyNames : Schema

propertyNames

Schema

Validation succeeds if the schema validates against every property name in the instance.

Value This keyword must be set to a valid JSON Schema Hint: Use the jsonschema metaschema and jsonschema lint commands to catch keywords set to invalid values
Kind Applicator
Applies To Object
Base Dialect 2020-12
Changed In None
Introduced In Draft 6
Vocabulary Applicator
Specification https://json-schema.org/draft/2020-12/json-schema-core.html#section-10.3.2.4
Metaschema https://json-schema.org/draft/2020-12/meta/applicator
Official Tests draft2020-12/propertyNames.json
Default {}
Annotation None
Affected By None
Affects None
Also See

The propertyNames keyword restricts object instances to only define properties whose names match the given schema. This keyword is evaluated against every property of the object instance, independently of keywords that indirectly introduce property names such as properties and patternProperties.

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 lowercase properties Schema 
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "propertyNames": { "pattern": "^[a-z]*$" }
}
Valid An object value with lowercase properties is valid Instance 
{ "foo": "bar" }
Valid An empty object value is valid Instance 
{}
Invalid An object value with uppercase or alphanumeric properties is invalid Instance 
{ "CamelCase": true, "alphanumeric123": false }
Valid A non-object value is valid Instance 
"Hello World"
A schema that incorrecly constrains object property names to an impossible type Schema 
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "propertyNames": { "type": "array" }
}
Invalid Any non-empty object value is invalid Instance 
{ "foo": "bar" }
Valid An empty object value is valid Instance 
{}
Valid A non-object value is valid Instance 
"Hello World"
A schema with a property name unsatisfiable collision between keywords Schema 
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "propertyNames": { "pattern": "^b" },
  "properties": {
    "foo": { "type": "integer" },
    "bar": { "type": "integer" }
  }
}
Invalid An object value with a defined property that does not match every name constraint is invalid Instance 
{ "foo": 1 }
Invalid An object value with a property that matches every name constraint but does not match its declaration is invalid Instance 
{ "bar": "should have been an integer" }
Valid An object value with a non-defined property that matches every name constraint is valid Instance 
{ "baz": "qux" }