IsNull
IsNull( value )
Parameters
Parameter | Type | Definition and Requirements |
---|---|---|
|
Any value, which is to be tested to determine whether it is a |
Returns
Returns a Boolean, indicating whether value
was a null
or
not.
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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