Object Functions

Object Functions

JSONata object function reference for use in Fuuz transforms, validation expressions, and data flows.

Fuuz Context

Where this applies in Fuuz: Object utilities help normalize heterogeneous payloads from connectors, merge partial updates, and emit well-formed objects to Fuuz topics.

• $keys/$lookup: Discover and retrieve fields across arrays of objects during mapping.
• $spread/$merge: Flatten nested objects or combine fragments into a single outbound structure.
• $each: Iterate key/value pairs to build logs or calculated outputs per property.
• $error/$assert: Enforce validation rules; surface failures to Fuuz observability.
• $type: Guard transformations with type checks when dealing with mixed payloads.

$keys()

Signature: $keys(object)

Returns an array containing the keys in the object. If the argument is an array of objects, then the array returned contains a de-duplicated list of all the keys in all of the objects.

$lookup()

Signature: $lookup(object, key)

Returns the value associated with key in object. If the first argument is an array of objects, then all of the objects in the array are searched, and the values associated with all occurrences of key are returned.

$spread()

Signature: $spread(object)

Splits an object containing key/value pairs into an array of objects, each of which has a single key/value pair from the input object. If the parameter is an array of objects, then the resultant array contains an object for every key/value pair in every object in the supplied array.

$merge()

Signature: $merge(array<object>)

Merges an array of objects into a single object containing all the key/value pairs from each of the objects in the input array. If any of the input objects contain the same key, then the returned object will contain the value of the last one in the array. It is an error if the input array contains an item that is not an object.

$sift()

Signature: $sift(object, function)

See definition under 'Higher-order functions'.

$each()

Signature: $each(object, function)

Returns an array containing the values returned by the function when applied to each key/value pair in the object.

The function parameter will get invoked with two arguments:

function(value, name)

where the value parameter is the value of each name/value pair in the object and name is its name. The name parameter is optional.

Example

$each(Address, function($v, $k) {$k & ": " & $v})

=>

[
  "Street: Hursley Park",
  "City: Winchester",
  "Postcode: SO21 2JN"
]

$error()

Signature: $error(message)

Deliberately throws an error with an optional message.

$assert()

Signature: $assert(condition, message)

If condition is true, the function returns undefined. If the condition is false, an exception is thrown with message as the message of the exception.

$type()

Signature: $type(value)

Evaluates the type of value and returns one of the following strings: "null", "number", "string", "boolean", "array", "object", or "function". Returns (non-string) undefined when value is undefined.

See Also

• Jsonata-Tutorial
• Numeric-Functions
• Array-Functions-How-To
• Predicate-Expressions

---

Source: support.fuuz.com