MONGOID-5752 Add #to_mql (#5895)

Author: comandeo-mongo

.rubocop.yml

@@ -78,6 +78,9 @@ RSpec/BeforeAfterAll:
 RSpec/DescribeClass:
   Enabled: false
 
+RSpec/ExampleLength:
+  Max: 10
+
 RSpec/ImplicitExpect:
   EnforcedStyle: is_expected
 

lib/mongoid/criteria/queryable.rb

@@ -86,6 +86,17 @@ def initialize_copy(other)
         @selector = other.selector.__deep_copy__
         @pipeline = other.pipeline.__deep_copy__
       end
+
+      # Returns selector and options of the criteria in form of MongoDB command.
+      #
+      # @return [ Hash ] The command.
+      def to_mql
+        {
+          :'$db' => database_name,
+          find: collection.name,
+          filter: selector
+        }.merge(options)
+      end
     end
   end
 end

spec/mongoid/criteria/queryable_mql_spec.rb

@@ -0,0 +1,92 @@
+# frozen_string_literal:true
+
+require 'spec_helper'
+
+describe Mongoid::Criteria::Queryable do
+  let(:db) do
+    Mongoid.default_client.database.name
+  end
+
+  let(:collection) do
+    Band.collection_name.to_s
+  end
+
+  shared_examples 'translatable to mql' do
+    it 'returns mql' do
+      expect(criteria.to_mql).to eq(mql)
+    end
+  end
+
+  describe '#to_mql' do
+    context 'when simple where' do
+      let(:criteria) do
+        Band.where(name: 'Depeche Mode')
+      end
+
+      let(:mql) do
+        {
+          '$db': db,
+          find: collection,
+          filter: { 'name' => 'Depeche Mode' }
+        }
+      end
+
+      it_behaves_like 'translatable to mql'
+    end
+
+    context 'with storage field name' do
+      let(:criteria) do
+        Band.where(:origin.ne => 'UK')
+            .in(years: [ 1995, 1996 ])
+      end
+
+      let(:mql) do
+        {
+          '$db': db,
+          find: collection,
+          filter: {
+            'origin' => { '$ne' => 'UK' },
+            'y' => { '$in' => [ 1995, 1996 ] }
+          }
+        }
+      end
+
+      it_behaves_like 'translatable to mql'
+    end
+
+    context 'with alias attribute' do
+      let(:criteria) do
+        Band.where(d: true)
+      end
+
+      let(:mql) do
+        {
+          '$db': db,
+          find: collection,
+          filter: { 'deleted' => true }
+        }
+      end
+
+      it_behaves_like 'translatable to mql'
+    end
+
+    context 'with options' do
+      let(:criteria) do
+        Band.where(genres: %w[rock hip-hop]).order(founded: 1).limit(100).skip(200)
+      end
+
+      let(:mql) do
+        {
+          '$db': db,
+          find: collection,
+          filter: { 'genres' => %w[rock hip-hop] },
+          limit: 100,
+          skip: 200,
+          sort: { 'founded' => 1 }
+        }
+      end
+
+      it_behaves_like 'translatable to mql'
+    end
+  end
+end