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filter

$filter​

Runs a processor on each element of the input array, keeping elements for which the processor succeeds and returning the processor's output value (consistent with standard processor semantics). Elements are filtered out if the processor throws or returns undefined. (Note that processor results are not checked for truthiness — only for definedness.)

Non-arrays are "filtered" as an empty array.

Parameters​

  • processor (any valid processor spec, optional): The processor to apply to each element. Elements where the processor returns undefined or throws are excluded from the result. If omitted, null/undefined elements are removed.

Example​

// Remove null and undefined values from an array
new Schema('array').transformer('$filter')

// Keep only numeric strings
new Schema('array').transformer({$filter: '$numeric'})

// Keep only values within range
new Schema('array').transformer({$filter: {$range: {min: 0, max: 100}}})

// Filter out non-email strings from a list
new Schema('object', {
  recipients: new Schema('array').transformer({$filter: '$email'}),
})