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Has value

hasValue validates that an array or plain object contains a value that is deeply equal to the target value.

It performs a deep search through the collection (array or plain object) looking for any value that matches the target using deep equality. If the value is not a collection or doesn't contain the target, the rule emits a single validation event. Otherwise, it produces no validation output.

Signature

Through the API:

.hasValue(target: unknown)

And internally:

export const hasValue = (target: unknown): ValidationRule
(value: unknown, path: FieldPath) => Promise<ReadonlyArray<JaneEvent>>

Events

Event code Description
object.has.missing-value Value is not an array or plain object
value.not.found Target value not found in the collection

Design rationale

  • Provides deep value existence validation for collections.
  • Works with both arrays and plain objects.
  • Uses deep equality comparison for complex nested values.
  • Searches recursively through nested collections.
  • Never coerces or normalizes — validation is explicit and opt-in.
  • Emits exactly one event per failure for clarity and composability.
  • Async-compatible and returns a readonly array of JaneEvent objects.

Invoke

hasValue runs only when explicitly included in a boundary or pipeline. It does not run automatically.

The rule activates when:

  • The value is any JavaScript value.
  • If the value is not an array or plain object, emits object.has.missing-value.
  • If the value is a collection but doesn't contain the target, emits value.not.found.
  • If the value is a collection containing the target → returns an empty result set.

Examples

Valid array containing target

await hasValue("apple")(["banana", "apple", "cherry"], "$");
// → []

Valid object containing target

await hasValue(42)({ name: "John", age: 42 }, "$");
// → []

Collection missing target

await hasValue("grape")(["banana", "apple", "cherry"], "$");
// → [
//     JaneEvent{
//       kind: "error",
//       code: "value.not.found",
//       path: "$",
//       ...
//     }
//   ]

Primitive value (invalid)

await hasValue("test")("hello", "$");
// → [
//     JaneEvent{
//       kind: "error",
//       code: "object.has.missing-value",
//       path: "$",
//       ...
//     }
//   ]