​
$boolean

Signature: $boolean(arg) Parameters:
  • arg - An argument to be cast to a Boolean.
Casts the argument to a Boolean using the following rules:
Argument typeResult
Booleanunchanged
string: emptyfalse
string: non-emptytrue
number: 0false
number: non-zerotrue
nullfalse
array: emptyfalse
array: contains a member that casts to truetrue
array: all members cast to falsefalse
object: emptyfalse
object: non-emptytrue
functionfalse

​
$not

Signature: $not(arg) Parameters:
  • arg - An argument to be cast to a Boolean and inverted.
Returns Boolean NOT on the argument. arg is first cast to a boolean.

​
$exists

Signature: $exists(arg) Parameters:
  • arg - An argument to chech the existence of.
Returns Boolean true if the arg expression evaluates to a value, or false if the expression does not match anything (e.g. a path to a non-existent field reference).