mongoid search in an array inside an array of hash - mongodb

Question

Say Object embeds_many searched_items
Here is the document:
{"_id": { "$oid" : "5320028b6d756e1981460000" },
"searched_items": [
{
"_id": { "$oid" : "5320028b6d756e1981470000" },
"hotel_id": 127,
"room_info": [
{
"price": 10,
"amenity_ids": [
1,
2
]
},
{
"price": 160,
"amenity_ids": null
}
]
},
{
"_id": { "$oid" : "5320028b6d756e1981480000" },
"hotel_id": 161,
"room_info": [
{
"price": 400,
"amenity_ids": [4,5]
}
]
}
]
}
I want to find the "searched_items" having room_info.amenity_ids IN [2,3].
I've tried
object.searched_items.where('room_info.amenity_ids' => [2, 3])
object.searched_items.where('room_info.amenity_ids' =>{'$in' => [2,3]}
with no luck

Answer 1

mongoid provides elem_match method for searching within objects of Array Type
e.g.
class A
include Mongoid::Document
field :some_field, type: Array
end
A.create(some_field: [{id: 'a', name: 'b'}, {id: 'c', name: 'd'}])
A.elem_match(some_field: { :id.in=> ["a", "c"] }) => will return the object
Let me know if you have any other doubts.
update
class SearchedHotel
include Mongoid::Document
field :hotel_id, type: String
field :room_info, type: Array
end
SearchedHotel.create(hotel_id: "1", room_info: [{id: 1, amenity_ids: [1,2], price: 600},{id: 2, amenity_ids: [1,2,3], price: 1000}])
SearchedHotel.create(hotel_id: "2", room_info: [{id: 3, amenity_ids: [1,2], price: 600}])
SearchedHotel.elem_match(room_info: {:amenity_ids.in => [1,2]})
Mongoid::Criteria
selector: {"room_info"=>{"$elemMatch"=>{"amenity_ids"=>{"$in"=>[1, 2]}}}}
options: {}
class: SearchedHotel
embedded: false
And it returns both the records. Am I missing something from your question/requirement. If yes, do let me know.

Answer 2

It's important to distinguish between top-level queries sent to the MongoDB server and
client-side operations on embedded-documents that are implemented by Mongoid.
This is the underlying confusion between the original question and the answer from #sandeep-kumar and associated comments.
The original question is all about the where clause on embedded documents after the query result has already been fetched.
The answer #sandeep-kumar and comments are all about top-level queries.
The following test covers both, showing how answers from #sandeep-kumar do work on the examples in your comments,
and also what does and does not work on your original question.
To summarize, Sandeep's answers do work for top-level queries.
Please review your code, if there are remaining problems, please post the exact Ruby code that summarizes the problem.
For your original question, please note that "object" has already been fetched from MongoDB,
and that you can verify this by looking at the log/test.log file.
The subsequent "where" operations are all client-side execution by Mongoid.
Simple "where" clauses do work at the embedded document level.
Complex "where" clauses involving nested array values don't seem to work -
I didn't really expect Mongoid to reimplement '$in' on the client-side.
Knowing that the "object" already has the query result,
and that the association "searched_items" gives you convenient access to the embedded documents,
you can write Ruby code to select what you want as in the following test.
Hope that this helps.
test/unit/my_object_test.rb
require 'test_helper'
require 'pp'
class MyObjectTest < ActiveSupport::TestCase
def setup
MyObject.delete_all
A.delete_all
SearchedHotel.delete_all
end
test "original question with client-side where operation on embedded documents" do
doc = {"_id"=>{"$oid"=>"5320028b6d756e1981460000"}, "searched_items"=>[{"_id"=>{"$oid"=>"5320028b6d756e1981470000"}, "hotel_id"=>127, "room_info"=>[{"price"=>10, "amenity_ids"=>[1, 2]}, {"price"=>160, "amenity_ids"=>nil}]}, {"_id"=>{"$oid"=>"5320028b6d756e1981480000"}, "hotel_id"=>161, "room_info"=>[{"price"=>400, "amenity_ids"=>[4, 5]}]}]}
MyObject.create(doc)
puts
object = MyObject.first
<<-EOT.split("\n").each{|line| puts "#{line}:"; eval "pp #{line}"}
object.searched_items.where('hotel_id' => 127).to_a
object.searched_items.where(:hotel_id.in => [127,128]).to_a
object.searched_items.where('room_info.amenity_ids' => {'$in' => [2,3]}).to_a
object.searched_items.where('room_info.amenity_ids'.to_sym.in => [2,3]).to_a
object.searched_items.select{|searched_item| searched_item.room_info.any?{|room_info| room_info['amenity_ids'] && !(room_info['amenity_ids'] & [2,3]).empty?}}.to_a
EOT
end
test "A comment - top-level queries" do
A.create(some_field: [{id: 'a', name: 'b', tag_ids: [6,7,8]}, {id: 'c', name: 'd'}, tag_ids: [5,6,7]])
A.create(some_field: [{id: 'a', name: 'b', tag_ids: [1,2,3]}, {id: 'c', name: 'd'}, tag_ids: [2,3,4]])
puts
pp A.where('some_field.tag_ids'.to_sym.in => [2,3]).to_a
pp A.elem_match(some_field: { :tag_ids.in => [2,3,4] }).to_a
end
test "SearchedHotel comment - top-level query" do
s = <<-EOT
[#<SearchedHotel _id: 53253c246d756e49a7030000, hotel_id: \"1\", room_info: [{\"id\"=>1, \"amenity_ids\"=>[1, 2], \"price\"=>600}, {\"id\"=>2, \"amenity_ids\"=>[1, 2, 3], \"price\"=>1000}]>, #<SearchedHotel _id: 53253c246d756e49a7040000, hotel_id: \"2\", room_info: [{\"id\"=>3, \"amenity_ids\"=>[1, 2], \"price\"=>600}]>]
EOT
a = eval(s.gsub('#<SearchedHotel ', '{').gsub(/>,/, '},').gsub(/>\]/, '}]').gsub(/_id: \h+, /, ''))
SearchedHotel.create(a)
puts
<<-EOT.split("\n").each{|line| puts "#{line}:"; eval "pp #{line}"}
SearchedHotel.elem_match(room_info: {:amenity_ids.in => [1,2]}).to_a
EOT
end
end
$ ruby -Ilib -Itest test/unit/my_object_test.rb
Run options:
# Running tests:
[1/3] MyObjectTest#test_A_comment_-_top-level_queries
[#<A _id: 5359329d7f11ba034b000002, some_field: [{"id"=>"a", "name"=>"b", "tag_ids"=>[1, 2, 3]}, {"id"=>"c", "name"=>"d"}, {"tag_ids"=>[2, 3, 4]}]>]
[#<A _id: 5359329d7f11ba034b000002, some_field: [{"id"=>"a", "name"=>"b", "tag_ids"=>[1, 2, 3]}, {"id"=>"c", "name"=>"d"}, {"tag_ids"=>[2, 3, 4]}]>]
[2/3] MyObjectTest#test_SearchedHotel_comment_-_top-level_query
SearchedHotel.elem_match(room_info: {:amenity_ids.in => [1,2]}).to_a:
[#<SearchedHotel _id: 5359329d7f11ba034b000003, hotel_id: "1", room_info: [{"id"=>1, "amenity_ids"=>[1, 2], "price"=>600}, {"id"=>2, "amenity_ids"=>[1, 2, 3], "price"=>1000}]>,
#<SearchedHotel _id: 5359329d7f11ba034b000004, hotel_id: "2", room_info: [{"id"=>3, "amenity_ids"=>[1, 2], "price"=>600}]>]
[3/3] MyObjectTest#test_original_question_with_client-side_where_operation_on_embedded_documents
object.searched_items.where('hotel_id' => 127).to_a:
[#<SearchedItem _id: 5359329d7f11ba034b000006, hotel_id: 127, room_info: [{"price"=>10, "amenity_ids"=>[1, 2]}, {"price"=>160, "amenity_ids"=>nil}]>]
object.searched_items.where(:hotel_id.in => [127,128]).to_a:
[#<SearchedItem _id: 5359329d7f11ba034b000006, hotel_id: 127, room_info: [{"price"=>10, "amenity_ids"=>[1, 2]}, {"price"=>160, "amenity_ids"=>nil}]>]
object.searched_items.where('room_info.amenity_ids' => {'$in' => [2,3]}).to_a:
[]
object.searched_items.where('room_info.amenity_ids'.to_sym.in => [2,3]).to_a:
[]
object.searched_items.select{|searched_item| searched_item.room_info.any?{|room_info| room_info['amenity_ids'] && !(room_info['amenity_ids'] & [2,3]).empty?}}.to_a:
[#<SearchedItem _id: 5359329d7f11ba034b000006, hotel_id: 127, room_info: [{"price"=>10, "amenity_ids"=>[1, 2]}, {"price"=>160, "amenity_ids"=>nil}]>]
Finished tests in 0.089544s, 33.5031 tests/s, 0.0000 assertions/s.
3 tests, 0 assertions, 0 failures, 0 errors, 0 skips