Method: Mongo::Collection::View::Readable#distinct

Defined in:

lib/mongo/collection/view/readable.rb

#distinct(field_name, opts = {}) ⇒ Array<Object>

Get a list of distinct values for a specific field.

Examples:

Get the distinct values.

collection_view.distinct('name')

Parameters:

• field_name (String, Symbol) —

  The name of the field.

• opts (Hash) (defaults to: {}) —

  Options for the distinct command.

• options (Hash) —

  a customizable set of options

Options Hash (opts):

• :max_time_ms (Integer) —

  The maximum amount of time to allow the command to run.

• :read (Hash) —

  The read preference options.

• :collation (Hash) —

  The collation to use.

Returns:

• (Array<Object>) —

  The list of distinct values.

Since:

• 2.0.0

# File 'lib/mongo/collection/view/readable.rb', line 318

def distinct(field_name, opts = {})
  if field_name.nil?
    raise ArgumentError, 'Field name for distinct operation must be not nil'
  end
  opts = @options.merge(opts) unless Mongo.broken_view_options
  cmd = { :distinct => collection.name,
          :key => field_name.to_s,
          :query => filter, }
  cmd[:maxTimeMS] = opts[:max_time_ms] if opts[:max_time_ms]
  if read_concern
    cmd[:readConcern] = Options::Mapper.transform_values_to_strings(
      read_concern)
  end
  Mongo::Lint.validate_underscore_read_preference(opts[:read])
  read_pref = opts[:read] || read_preference
  selector = ServerSelector.get(read_pref || server_selector)
  with_session(opts) do |session|
    read_with_retry(session, selector) do |server|
      Operation::Distinct.new(
        selector: cmd,
        db_name: database.name,
        options: {:limit => -1},
        read: read_pref,
        session: session,
        comment: opts[:comment],
        # For some reason collation was historically accepted as a
        # string key. Note that this isn't documented as valid usage.
        collation: opts[:collation] || opts['collation'] || collation,
      ).execute(server, context: Operation::Context.new(client: client, session: session))
    end.first['values']
  end
end