Function.firstWhere()

Get the first matching accessible user-defined Function document.

Signature

Function.firstWhere(predicate: () => Boolean)): <Function> | Null

Function.firstWhere(predicate: (val: Function) => Boolean)): <Function> | Null

Description

Each user-defined function (UDF) document in a Fauna database is represented by a function object. Function.firstWhere() returns the first accessible function object that matches the predicate function. When no matching UDF documents exist or all matching UDF documents are inaccessible, returns null.

The predicate function must return a Boolean.

Parameters

Parameter Type Required Description

predicate

Function

Yes

Anonymous function that compares values in each UDF document and returns true for matches or false for mismatches.

predicate parameters:

Parameter Type Required Description

val

Collection

UDF object to compare. If omitted, use dot notation to access function properties.

Return value

One of:

Type Description

Function

First accessible UDF document matching the predicate function. See Function document definition.

Null

When no UDF documents match the predicate function or all matching UDF documents are inaccessible.

Examples

Get the first UDF when at least one matching UDF document exists and is accessible:

Function.firstWhere(.name.includes('b'))
{
  name: "Double",
  coll: Function,
  ts: Time("2022-10-25T21:01:19.310Z"),
  body: "(x) => x + x"
}

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