how to query out entries with a field of blank array by mongoid?

Question

my model is:(with mongoid version2)

class Trip
  include Mongoid::Document
  include Mongoid::Timestamps
  include Mongoid::MultiParameterAttributes

  field :images, :type => Array, :default => []
end

i can search out entries, which its images size is not 0 by:

Trip.where(:images.size => 1).size #=>1, correct

while this method can not used for searching blank array field:

Trip.where(:images.size => 0).size #=>0, error, as i do have many entries with default [] field.

how can i fix it?

rubish · Accepted Answer · 2012-05-31 17:14:36Z

2

Try the following query, I hope it should work:

Trip.all.or(:images.size => 0).or(:images => nil)

answered May 31, 2012 at 17:14

rubish

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Gary Murakami · Accepted Answer · 2012-05-31 19:52:52Z

The following test verifies that the latest edit by @rubish works.

Trip.all.or(:images.size => 0).or(:images => nil)

test/unit/trip_test.rb

require 'test_helper'

class TripTest < ActiveSupport::TestCase
  def setup
    Trip.delete_all
  end

  test "criteria or" do
    Trip.create(:images => nil)
    Trip.create(:images => [])
    Trip.create(:images => ['xyzzy'])
    assert_equal(3, Trip.count)
    puts "Trip.all images:#{Trip.all.to_a.map(&:images).inspect}"
    trips_with_images_empty_or_nil = Trip.all.or(:images.size => 0).or(:images => nil).to_a
    puts "trips_with_images_empty_or_nil images: #{trips_with_images_empty_or_nil.map(&:images).inspect}"
    assert_equal(2, trips_with_images_empty_or_nil.size)
  end
end

test output

Run options: --name=test_criteria_or

# Running tests:

Trip.all images:[nil, [], ["xyzzy"]]
trips_with_images_empty_or_nil images: [nil, []]
.

Finished tests in 0.009099s, 109.9022 tests/s, 219.8044 assertions/s.

1 tests, 2 assertions, 0 failures, 0 errors, 0 skips

daino3 · Accepted Answer · 2015-06-04 16:05:15Z

1

Just adding my solution which may be helpful (latest syntax as well):

scope :without_images, -> { any_of(:images.with_size => 0, images: nil) }

answered Jun 4, 2015 at 16:05

daino3

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