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never

$never​

Inverts a processor - Returns the input if the wrapped processor throws or returns an undefined value. Throw a constraint error if the wrapped processor returns a defined value.

See $not to enforce falseyness.

Parameters​

  • value (ProcessorSpec, required): The processor specification to negate (must not return a defined value).

Example​

// Blacklist specific values — reject any input that is found in the lookup table
new Schema('string').validator({$never: {$lookup: {admin: true, root: true}}})

// Ensure a value does not parse as a number (must be a non-numeric string)
new Schema('string').validator({$never: '$numeric'})

// Reject any value that resolves from $get (path must NOT exist)
new Schema('object').validator({$never: {$get: 'deprecated.field'}})