Merge pull request mongodb#4300 from jonhyman/feature/elemMatch-matches

Add support for $elemMatch in Matchable#matches?

lib/mongoid/matchable.rb

@@ -12,6 +12,7 @@
 require "mongoid/matchable/nin"
 require "mongoid/matchable/or"
 require "mongoid/matchable/size"
+require "mongoid/matchable/elem_match"
 
 module Mongoid
 
@@ -27,6 +28,7 @@ module Matchable
     # @since 1.0.0
     MATCHERS = {
       "$all" => All,
+      "$elemMatch" => ElemMatch,
       "$and" => And,
       "$exists" => Exists,
       "$gt" => Gt,
@@ -149,7 +151,11 @@ def extract_attribute(document, key)
             end
           end
         else
-          document.attributes[key_string]
+          if document.is_a?(Hash)
+            document[key_string]
+          else
+            document.attributes[key_string]
+          end
         end
       end
     end

lib/mongoid/matchable/elem_match.rb

@@ -0,0 +1,28 @@
+# encoding: utf-8
+module Mongoid
+  module Matchable
+
+    class ElemMatch < Default
+
+      # Return true if a given predicate matches a sub document entirely
+      #
+      # @example Do the values match?
+      #   matcher.matches?({"$elemMatch" => {"a" => 1, "b" => 2}})
+      #
+      # @param [ Hash ] value The values to check.
+      #
+      # @return [ true, false ] If the values match.
+      def matches?(value)
+        if !@attribute.is_a?(Array) || !value.kind_of?(Hash) || !value["$elemMatch"].kind_of?(Hash)
+          return false
+        end
+
+        return @attribute.any? do |sub_document|
+          value["$elemMatch"].all? do |k, v|
+            Matchable.matcher(sub_document, k, v).matches?(v)
+          end
+        end
+      end
+    end
+  end
+end

spec/mongoid/matchable/elem_match_spec.rb

@@ -0,0 +1,86 @@
+require "spec_helper"
+
+describe Mongoid::Matchable::ElemMatch do
+
+  let(:attribute) {[{"a" => 1, "b" => 2}, {"a" => 2, "b" => 2}, {"a" => 3, "b" => 1}]}
+  let(:matcher) do
+    described_class.new(attribute)
+  end
+
+  describe "#matches?" do
+
+    context "when the attribute is not an array" do
+
+      let(:attribute) {"string"}
+
+      it "returns false" do
+        expect(matcher.matches?("$elemMatch" => {"a" => 1})).to be false
+      end
+    end
+
+    context "when the $elemMatch is not a hash" do
+
+      let(:attribute) {"string"}
+
+      it "returns false" do
+        expect(matcher.matches?("$elemMatch" => [])).to be false
+      end
+    end
+
+    context "when there is a sub document that matches the criteria" do
+
+      it "returns true" do
+        expect(matcher.matches?("$elemMatch" => {"a" => 1})).to be true
+      end
+
+      context "when evaluating multiple fields of the subdocument" do
+
+        it "returns true" do
+          expect(matcher.matches?("$elemMatch" => {"a" => 1, "b" => 2})).to be true
+        end
+
+        context "when the $elemMatch document keys are out of order" do
+
+          it "returns true" do
+            expect(matcher.matches?("$elemMatch" => {"b" => 2, "a" => 1})).to be true
+          end
+        end
+      end
+
+      context "when using other operators that match" do
+
+        it "returns true" do
+          expect(matcher.matches?("$elemMatch" => {"a" => {"$in" => [1]}, "b" => {"$gt" => 1}})).to be true
+        end
+      end
+    end
+
+    context "when there is not a sub document that matches the criteria" do
+
+      it "returns false" do
+        expect(matcher.matches?("$elemMatch" => {"a" => 10})).to be false
+      end
+
+      context "when evaluating multiple fields of the subdocument" do
+
+        it "returns false" do
+          expect(matcher.matches?("$elemMatch" => {"a" => 1, "b" => 3})).to be false
+        end
+      end
+
+      context "when using other operators that do not match" do
+
+        it "returns true" do
+          expect(matcher.matches?("$elemMatch" => {"a" => {"$in" => [1]}, "b" => {"$gt" => 10}})).to be false
+        end
+      end
+    end
+
+    context "when using a criteria that matches partially but not a single sub document" do
+
+      it "returns false" do
+        expect(matcher.matches?("$elemMatch" => {"a" => 3, "b" => 2})).to be false
+      end
+    end
+  end
+end

spec/mongoid/matchable_spec.rb

@@ -112,6 +112,126 @@
         end
       end
 
+      context "when using $elemMatch" do
+
+        context "one predicate" do
+
+          let(:selector) do
+            {
+              "occupants" => {"$elemMatch" => {"name" => "Tim"}}
+            }
+          end
+
+          context "and there is a matching sub document" do
+
+            it "returns true" do
+              expect(document.locations.first.matches?(selector)).to be true
+            end
+
+            context "using $in" do
+              let(:selector) do
+                {
+                  "occupants" => {"$elemMatch" => {"name" => {"$in" => ["Tim", "Alice"]}}}
+                }
+              end
+
+              it "returns true" do
+                expect(document.locations.first.matches?(selector)).to be true
+              end
+            end
+          end
+
+          context "and there is not a matching sub document" do
+
+            let(:selector) do
+              {
+                "occupants" => {"$elemMatch" => {"name" => "Lyle"}}
+              }
+            end
+
+            it "returns false" do
+              expect(document.locations.first.matches?(selector)).to be false
+            end
+
+            context "using $in" do
+              let(:selector) do
+                {
+                  "occupants" => {"$elemMatch" => {"name" => {"$in" => ["Lyfe", "Alice"]}}}
+                }
+              end
+
+              it "returns false" do
+                expect(document.locations.first.matches?(selector)).to be false
+              end
+            end
+          end
+        end
+
+        context "multiple predicates" do
+
+          before do
+            document.locations = [
+              Location.new(
+                name: 'No.1',
+                info: { 'door' => 'Red'},
+                occupants: [{'name' => 'Tim', 'eye_color' => 'brown'}, {'name' => 'Alice', 'eye_color' => 'blue'}]
+              )
+            ]
+          end
+
+          let(:selector) do
+            {
+              "occupants" => {"$elemMatch" => {"name" => "Tim", "eye_color" => "brown"}}
+            }
+          end
+
+          context "and there is a matching sub document" do
+
+            it "returns true" do
+              expect(document.locations.first.matches?(selector)).to be true
+            end
+
+            context "using $in and $ne in the $elemMatch to include the element" do
+
+              let(:selector) do
+                {
+                  "occupants" => {"$elemMatch" => {"name" => {"$in" => ["Tim"]}, "eye_color" => {"$ne" => "blue"}}}
+                }
+              end
+
+              it "returns true" do
+                expect(document.locations.first.matches?(selector)).to be true
+              end
+            end
+          end
+
+          context "and there is not a matching sub document" do
+
+            let(:selector) do
+              {
+                "occupants" => {"$elemMatch" => {"name" => "Tim", "eye_color" => "blue"}}
+              }
+            end
+
+            it "returns false" do
+              expect(document.locations.first.matches?(selector)).to be false
+            end
+
+            context "using $ne in the $elemMatch to exclude the element" do
+
+              let(:selector) do
+                {
+                  "occupants" => {"$elemMatch" => {"name" => {"$in" => ["Tim"]}, "eye_color" => {"$ne" => "brown"}}}
+                }
+              end
+
+              it "returns false" do
+                expect(document.locations.first.matches?(selector)).to be false
+              end
+            end
+          end
+        end
+      end
     end
 
     context "when performing simple matching" do