Exists

Copied!
( ref, [ts] )

Description

The Exists function returns boolean true if the provided ref exists at the specified timestamp (in the case of a document), or is non-empty (in the case of a set), and false otherwise.

Parameters

Parameter Type Definition and Requirements

ref

Reference

The Reference that uniquely identifies a document within the database.

ts

Long or Timestamp

Optional - The timestamp at which the existence of the Reference is checked. Can be expressed as either a number of UNIX microseconds since epoch, or as a Timestamp. Defaults to the current time.

For large values of ts (positive or negative), you may need to express the value in a String to maintain numeric precision (Fauna uses 64-bit signed integers, whereas JavaScript uses 53-bit signed integers).

Returns

A boolean value

Examples

The following query checks for the existence of a ref pointing at a document in the spells collection at value 181388642046968320L. Since this ref is present at the current time, true is returned.

Copied!
(
  (('spells'), '181388642046968320')
)
true
Query metrics:

  •    bytesIn:  68

  •   bytesOut:  17

  • computeOps:   1

  •    readOps:   1

  •   writeOps:   0

  •  readBytes: 112

  • writeBytes:   0

  •  queryTime: 4ms

  •    retries:   0

Is this article helpful? 

Tell Fauna how the article can be improved:
 Visit Fauna's forums or email docs@fauna.com

Thank you for your feedback!