FQL v4 will be decommissioned on June 30, 2025. Ensure that you complete your migration from FQL v4 to FQL v10 by that date. Fauna accounts created after August 21, 2024 must use FQL v10. These accounts will not be able to run FQL v4 queries or access the v4 Dashboard. For more details, see the v4 EOL announcement and migration guide. Contact support@fauna.com with any questions. |
IsNull
This reference topic applies to FQL v4. Go to this page for the latest FQL v10 reference topics. |
IsNull( value )
Parameters
Parameter | Type | Definition and Requirements |
---|---|---|
|
Any |
Any value, which is to be tested to determine whether it is a |
Examples
The following query uses Map
to iterate over an array of all of
the types of values that can be tested by a type-check function, passing
each item into a Lambda
function that returns an object, which
contains the value and the result of calling IsNull
with that
value:
[
{ value: [ 'array' ], IsNull: false },
{ value: true, IsNull: false },
{ value: false, IsNull: false },
{ value: { '0': 1, '1': 2, '2': 3, '3': 4 }, IsNull: false },
{ value: [ 1, 2, 3, 4 ], IsNull: false },
{ value: Collection("Letters"), IsNull: false },
{ value: Ref(Credentials(), "302043979982045696"), IsNull: false },
{ value: Database("child_db"), IsNull: false },
{ value: Date("2019-11-12"), IsNull: false },
{ value: Ref(Collection("Letters"), "123"), IsNull: false },
{ value: 10.1, IsNull: false },
{ value: Function("double"), IsNull: false },
{ value: Index("letters"), IsNull: false },
{ value: 10, IsNull: false },
{ value: Ref(Keys(), "1"), IsNull: false },
{ value: Query(Lambda("x", Var("x"))), IsNull: false },
{ value: null, IsNull: true },
{ value: { x: 10 }, IsNull: false },
{ value: Role("employees"), IsNull: false },
{ value: Match(Index("letters")), IsNull: false },
{ value: 'ten', IsNull: false },
{ value: '10', IsNull: false },
{ value: Time("2020-07-06T12:34:56.789Z"), IsNull: false },
{ value: Ref(Tokens(), "1"), IsNull: false }
]
This query operates on a pre-existing schema, which is not provided here. Also, the query is executed via a client connection, that uses a secret
acquired by calling the |
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