Use Builder class to manipulate args into docs formatted for driver API

lib/rom/mongo.rb

@@ -1,3 +1,4 @@
+require 'mongo'
 require 'rom/core'
 
 require 'rom/mongo/version'

lib/rom/mongo/builder.rb

@@ -0,0 +1,32 @@
+module ROM
+  module Mongo
+    module Builder
+
+      SORT_DIRECTION_MAP = {
+          asc: ::Mongo::Index::ASCENDING,
+          desc: ::Mongo::Index::DESCENDING,
+      }
+
+      extend self
+
+      def to_projection(fields)
+        fields.inject({}) do |doc, f|
+          doc.merge!(f => 1)
+        end
+      end
+
+
+      def to_sort_doc(doc)
+        doc.inject({}) do |sort_doc, (key, value)|
+          if SORT_DIRECTION_MAP.values.include?(value)
+            sort_doc.merge!(key => value)
+          elsif direction = SORT_DIRECTION_MAP[value]
+            sort_doc.merge!(key => direction)
+          else
+            sort_doc
+          end
+        end
+      end
+    end
+  end
+end

lib/rom/mongo/dataset.rb

@@ -1,3 +1,5 @@
+require 'rom/mongo/builder'
+
 module ROM
   module Mongo
     class Dataset
@@ -46,10 +48,7 @@ def where(doc)
       end
 
       def only(fields)
-        projection_doc = fields.inject({}) do |doc, f|
-          doc.merge!(f => 1)
-        end
-        dataset(criteria.projection(projection_doc))
+        dataset(criteria.projection(Builder.to_projection(fields)))
       end
 
       def without(fields)
@@ -65,7 +64,7 @@ def skip(value)
       end
 
       def sort(value)
-        dataset(criteria.sort(value))
+        dataset(criteria.sort(Builder.to_sort_doc(value)))
       end
       alias :order :sort
 

lib/rom/mongo/gateway.rb

@@ -1,4 +1,3 @@
-require 'mongo'
 require 'uri'
 
 require 'rom/gateway'

spec/unit/builder_spec.rb

@@ -0,0 +1,55 @@
+require 'spec_helper'
+
+RSpec.describe ROM::Mongo::Builder do
+
+  describe '#to_projection' do
+
+    let(:result) do
+      described_class.to_projection([:name, :address])
+    end
+
+    it 'converts the fields into a document with 1 values' do
+      expect(result).to eq({ name: 1, address: 1})
+    end
+  end
+
+  describe '#to_sort_doc' do
+
+    let(:result) do
+      described_class.to_sort_doc(arg)
+    end
+
+    context 'when symbols are used as the direction' do
+
+      let(:arg) do
+        {name: :asc, address: :desc}
+      end
+
+      it 'converts the fields into a document with 1 values' do
+        expect(result).to eq({ name: 1, address: -1 })
+      end
+    end
+
+    context 'when integers are used as the direction' do
+
+      let(:arg) do
+        {name: 1, address: -1}
+      end
+
+      it 'converts the fields into a document with 1 values' do
+        expect(result).to eq({ name: 1, address: -1 })
+      end
+    end
+
+    context 'when the direction is invalid' do
+
+      let(:arg) do
+        {name: 1, address: :invalid}
+      end
+
+      it 'ignores the invalid direction' do
+        expect(result).to eq({ name: 1 })
+      end
+    end
+  end
+end

spec/unit/relation_spec.rb

@@ -13,18 +13,18 @@
 
   describe '#order' do
     it 'sorts documents' do
-      expect(users.order(name: Mongo::Index::ASCENDING).only(:name).without(:_id).to_a.map(&:to_h)).
+      expect(users.order(name: :asc).only(:name).without(:_id).to_a.map(&:to_h)).
         to eql([{name: 'Jane',}, {name: 'Joe'}])
 
-      expect(users.order(name: Mongo::Index::DESCENDING).only(:name).without(:_id).to_a.map(&:to_h)).
+      expect(users.order(name: :desc).only(:name).without(:_id).to_a.map(&:to_h)).
         to eql([{name: 'Joe'}, {name: 'Jane'}])
     end
 
     it 'supports mutli-field sorting' do
-      expect(users.order(name: Mongo::Index::ASCENDING, email: Mongo::Index::ASCENDING).only(:name).without(:_id).to_a.map(&:to_h)).
+      expect(users.order(name: :asc, email: :asc).only(:name).without(:_id).to_a.map(&:to_h)).
         to eql([{name: 'Jane',}, {name: 'Joe'}])
 
-      expect(users.order(email: Mongo::Index::ASCENDING, name: Mongo::Index::ASCENDING).only(:name).without(:_id).to_a.map(&:to_h)).
+      expect(users.order(email: :asc, name: :asc).only(:name).without(:_id).to_a.map(&:to_h)).
         to eql([{name: 'Joe',}, {name: 'Jane'}])
     end
   end