Method: Mongo::Collection::View::Readable#aggregate

Defined in:
lib/mongo/collection/view/readable.rb

#aggregate(pipeline, options = {}) ⇒ Aggregation

Execute an aggregation on the collection view.

Examples:

Aggregate documents.

view.aggregate([
  { "$group" => { "_id" => "$city", "tpop" => { "$sum" => "$pop" }}}
])

Parameters:

  • pipeline (Array<Hash>) —

    The aggregation pipeline.

  • options (Hash) (defaults to: {}) —

    The aggregation options.

Options Hash (options):

  • :allow_disk_use (true, false) —

    Set to true if disk usage is allowed during the aggregation.

  • :batch_size (Integer) —

    The number of documents to return per batch.

  • :bypass_document_validation (true, false) —

    Whether or not to skip document level validation.

  • :collation (Hash) —

    The collation to use.

  • :comment (Object) —

    A user-provided comment to attach to this command.

  • :hint (String) —

    The index to use for the aggregation.

  • :let (Hash) —

    Mapping of variables to use in the pipeline. See the server documentation for details.

  • :max_time_ms (Integer) —

    The maximum amount of time in milliseconds to allow the aggregation to run. This option is deprecated, use :timeout_ms instead.

  • :session (Session) —

    The session to use.

  • :timeout_ms (Integer) —

    The operation timeout in milliseconds. Must be a non-negative integer. An explicit value of 0 means infinite. The default value is unset which means the value is inherited from the collection or the database or the client.

Returns:

Since:

  • 2.0.0



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# File 'lib/mongo/collection/view/readable.rb', line 61

def aggregate(pipeline, options = {})
  options = @options.merge(options) unless Mongo.broken_view_options
  aggregation = Aggregation.new(self, pipeline, options)

  # Because the $merge and $out pipeline stages write documents to the
  # collection, it is necessary to clear the cache when they are performed.
  #
  # Opt to clear the entire cache rather than one namespace because
  # the $out and $merge stages do not have to write to the same namespace
  # on which the aggregation is performed.
  QueryCache.clear if aggregation.write?

  aggregation
end