Filter Node

The filter node conditionally passes or drops a message based on a query against the message context.

When to Use

Field	Type	Required	Description
`filter`	object	Yes	MongoDB-style query object

Filters can match against two namespaces:

Prefix	Targets
`data.`	Fields in the message payload
`metadata.`	`appId`, `channel`, `event`

Omitting a prefix matches directly against the top-level object.

Operator	Meaning
`$eq`	Equal
`$ne`	Not equal
`$gt`	Greater than
`$gte`	Greater than or equal
`$lt`	Less than
`$lte`	Less than or equal
`$in`	Value is in array
`$nin`	Value is not in array
`$and`	All conditions must match
`$or`	At least one condition must match
`$nor`	None of the conditions match
`$not`	Inverts a condition

Pass only messages where data.active is true:

{
  "filter": {
    "data.active": true
  }
}

Pass only message events:

{
  "filter": {
    "metadata.event": "message"
  }
}

Pass only messages where data.priority >= 5 and the event is alert:

{
  "filter": {
    "$and": [
      { "data.priority": { "$gte": 5 } },
      { "metadata.event": "alert" }
    ]
  }
}

{
  "filter": {
    "data.userId": { "$in": ["user-1", "user-2", "user-3"] }
  }
}

When the filter condition is not met the pipeline stops. No further nodes run and no broadcast is emitted. The client receives an error reply.