Merge branch 'where_object_method'; close #377

lib/paper_trail/serializers/json.rb

@@ -12,6 +12,25 @@ module PaperTrail
       def dump(object)
         ActiveSupport::JSON.encode object
       end
+
+      # Returns a SQL condition to be used to match the given field and value in
+      # the serialized object.
+      def where_object_condition(arel_field, field, value)
+        # Convert to JSON to handle strings and nulls correctly.
+        json_value = value.to_json
+
+        # If the value is a number, we need to ensure that we find the next
+        # character too, which is either `,` or `}`, to ensure that searching
+        # for the value 12 doesn't yield false positives when the value is
+        # 123.
+        if value.is_a? Numeric
+          arel_field.matches("%\"#{field}\":#{json_value},%").
+            or(
+          arel_field.matches("%\"#{field}\":#{json_value}}%"))
+        else
+          arel_field.matches("%\"#{field}\":#{json_value}%")
+        end
+      end
     end
   end
 end

lib/paper_trail/serializers/yaml.rb

@@ -12,6 +12,12 @@ module PaperTrail
       def dump(object)
         ::YAML.dump object
       end
+
+      # Returns a SQL condition to be used to match the given field and value in
+      # the serialized object.
+      def where_object_condition(arel_field, field, value)
+        arel_field.matches("%\n#{field}: #{value}\n%")
+      end
     end
   end
 end

lib/paper_trail/version_concern.rb

@@ -68,6 +68,21 @@ module PaperTrail
         end
       end
 
+      # Performs an attribute search on the serialized object by invoking the
+      # identically-named method in the serializer being used.
+      def where_object(args = {})
+        raise ArgumentError, 'expected to receive a Hash' unless args.is_a?(Hash)
+        arel_field = arel_table[:object]
+
+        where_conditions = args.map do |field, value|
+          PaperTrail.serializer.where_object_condition(arel_field, field, value)
+        end.reduce do |condition1, condition2|
+          condition1.and(condition2)
+        end
+
+        where(where_conditions)
+      end
+
       def primary_key_is_int?
         @primary_key_is_int ||= columns_hash[primary_key].type == :integer
       rescue
@@ -190,7 +205,7 @@ module PaperTrail
 
     def index
       table = self.class.arel_table unless @index
-      @index ||= 
+      @index ||=
         if self.class.primary_key_is_int?
           sibling_versions.select(table[self.class.primary_key]).order(table[self.class.primary_key].asc).index(self)
         else

spec/models/version_spec.rb

@@ -40,5 +40,49 @@ describe PaperTrail::Version do
         end
       end
     end
+
+    describe "Class" do
+      describe :where_object do
+        it { PaperTrail::Version.should respond_to(:where_object) }
+
+        context "invalid arguments" do
+          it "should raise an error" do
+            expect { PaperTrail::Version.where_object(:foo) }.to raise_error(ArgumentError)
+            expect { PaperTrail::Version.where_object([]) }.to raise_error(ArgumentError)
+          end
+        end
+
+        context "valid arguments", :versioning => true do
+          let(:widget) { Widget.new }
+          let(:name) { Faker::Name.first_name }
+          let(:int) { rand(10) + 1 }
+
+          before do
+            widget.update_attributes!(:name => name, :an_integer => int)
+            widget.update_attributes!(:name => 'foobar', :an_integer => 100)
+            widget.update_attributes!(:name => Faker::Name.last_name, :an_integer => 15)
+          end
+
+          context "`serializer == YAML`" do
+            specify { PaperTrail.serializer == PaperTrail::Serializers::YAML }
+
+            it "should be able to locate versions according to their `object` contents" do
+              PaperTrail::Version.where_object(:name => name).should == [widget.versions[1]]
+              PaperTrail::Version.where_object(:an_integer => 100).should == [widget.versions[2]]
+            end
+          end
+
+          context "`serializer == JSON`" do
+            before { PaperTrail.serializer = PaperTrail::Serializers::JSON }
+            specify { PaperTrail.serializer == PaperTrail::Serializers::JSON }
+
+            it "should be able to locate versions according to their `object` contents" do
+              PaperTrail::Version.where_object(:name => name).should == [widget.versions[1]]
+              PaperTrail::Version.where_object(:an_integer => 100).should == [widget.versions[2]]
+            end
+          end
+        end
+      end
+    end
   end
 end

test/unit/serializers/json_test.rb

@@ -37,4 +37,39 @@ class JSONTest < ActiveSupport::TestCase
     end
   end
 
+  context '`where_object` class method' do
+    context "when value is a string" do
+      should 'construct correct WHERE query' do
+        matches = PaperTrail::Serializers::JSON.where_object_condition(
+          PaperTrail::Version.arel_table[:object], :arg1, "Val 1")
+
+        assert matches.instance_of?(Arel::Nodes::Matches)
+        assert_equal matches.right, "%\"arg1\":\"Val 1\"%"
+      end
+    end
+
+    context "when value is `null`" do
+      should 'construct correct WHERE query' do
+        matches = PaperTrail::Serializers::JSON.where_object_condition(
+          PaperTrail::Version.arel_table[:object], :arg1, nil)
+
+        assert matches.instance_of?(Arel::Nodes::Matches)
+        assert_equal matches.right, "%\"arg1\":null%"
+      end
+    end
+
+    context "when value is a number" do
+      should 'construct correct WHERE query' do
+        grouping = PaperTrail::Serializers::JSON.where_object_condition(
+          PaperTrail::Version.arel_table[:object], :arg1, -3.5)
+
+        assert grouping.instance_of?(Arel::Nodes::Grouping)
+        matches = grouping.select { |v| v.instance_of?(Arel::Nodes::Matches) }
+        # Numeric arguments need to ensure that they match for only the number, not the beginning 
+        # of a #, so it uses an Grouping matcher (See notes on `PaperTrail::Serializers::JSON`)
+        assert_equal matches.first.right, "%\"arg1\":-3.5,%"
+        assert_equal matches.last.right, "%\"arg1\":-3.5}%"
+      end
+    end
+  end
 end

test/unit/serializers/yaml_test.rb

@@ -37,4 +37,12 @@ class YamlTest < ActiveSupport::TestCase
     end
   end
 
+  context '`where_object` class method' do
+    should 'construct correct WHERE query' do
+      matches = PaperTrail::Serializers::YAML.where_object_condition(
+        PaperTrail::Version.arel_table[:object], :arg1, "Val 1")
+      assert matches.instance_of?(Arel::Nodes::Matches)
+      assert_equal matches.right, "%\narg1: Val 1\n%"
+    end
+  end
 end