avoid blank hash in embeded parameter

lib/her/model/parse.rb

@@ -56,14 +56,23 @@ def to_params(attributes, changes={})
         # @private
         # TODO: Handle has_one
         def embeded_params(attributes)
-          associations[:has_many].select { |a| attributes.include?(a[:data_key])}.compact.inject({}) do |hash, association|
-            params = attributes[association[:data_key]].map(&:to_params)
-            next if params.empty?
-            if association[:class_name].constantize.include_root_in_json?
-              root = association[:class_name].constantize.root_element
-              hash[association[:data_key]] = params.map { |n| n[root] }
+          (associations[:has_many] + associations[:has_one]).select { |a| attributes.include?(a[:data_key])}.compact.inject({}) do |hash, association|
+            # avoid hash is nil
+            hash ||= {}
+            params = {}
+            if attributes[association[:data_key]].respond_to?(:map)
+              params = attributes[association[:data_key]].map(&:to_params)
             else
-              hash[association[:data_key]] = params
+              params = attributes[association[:data_key]].to_params
+            end
+            # avoid nil in inject when params.empty?
+            if params.present?
+              if association[:class_name].constantize.include_root_in_json?
+                root = association[:class_name].constantize.root_element
+                hash[association[:data_key]] = params.map { |n| n[root] }
+              else
+                hash[association[:data_key]] = params
+              end
             end
             hash
           end

spec/model/associations_spec.rb

@@ -112,7 +112,7 @@
 
       spawn_model "Foo::User" do
         has_many :comments, class_name: "Foo::Comment"
-        has_one :role
+        has_one :role, class_name: "Foo::Role"
         belongs_to :organization
         has_many :posts, :inverse_of => :admin
       end

spec/model/parse_spec.rb

@@ -342,4 +342,85 @@ def to_params
       expect(user.to_params).to eql(:user => {:first_name => 'Someone'})
     end
   end
+
+  context "two has_many relations" do
+    before do
+      Her::API.setup :url => "https://api.example.com" do |builder|
+        builder.use Her::Middleware::FirstLevelParseJSON
+        builder.use Faraday::Request::UrlEncoded
+      end
+
+      Her::API.default_api.connection.adapter :test do |stub|
+        stub.get("/users/1") { |env| [200, {}, { :id => 1, :first_name => "Gooby", :last_name => "Pls", :posts=>[], :comments => [{ :id => 4, :body => "They're having a FIRESALE?" }] }.to_json] }
+      end
+
+      spawn_model "Foo::User" do
+        has_many :posts, class_name:"Foo::Post"
+        has_many :comments, class_name:"Foo::Comment"
+        attributes :id, :first_name, :last_name
+      end
+      spawn_model "Foo::Post" do
+        attributes :body
+      end
+      spawn_model "Foo::Comment" do
+        attributes :id, :body
+      end
+    end
+
+    it "get user json with comments and blank post" do
+      user = Foo::User.find(1)
+      expect(user.to_params).to eq({ :id => 1, :first_name => "Gooby", :last_name => "Pls", :posts=>[], :comments => [{ :id => 4, :body => "They're having a FIRESALE?" }] })
+    end
+  end
+
+  context "one has_many relation" do
+    before do
+      Her::API.setup :url => "https://api.example.com" do |builder|
+        builder.use Her::Middleware::FirstLevelParseJSON
+        builder.use Faraday::Request::UrlEncoded
+      end
+
+      Her::API.default_api.connection.adapter :test do |stub|
+        stub.get("/users/1") { |env| [200, {}, { :id => 1, :first_name => "Gooby", :last_name => "Pls", :comments => [] }.to_json] }
+      end
+
+      spawn_model "Foo::User" do
+        has_many :comments, class_name:"Foo::Comment"
+        attributes :id, :first_name, :last_name
+      end
+      spawn_model "Foo::Comment" do
+        attributes :id, :body
+      end
+    end
+
+    it "get user json with blank comments" do
+      user = Foo::User.find(1)
+      expect(user.to_params).to eq({ :id => 1, :first_name => "Gooby", :last_name => "Pls", :comments => [] })
+    end
+  end
+  context "one has_one relation" do
+    before do
+      Her::API.setup :url => "https://api.example.com" do |builder|
+        builder.use Her::Middleware::FirstLevelParseJSON
+        builder.use Faraday::Request::UrlEncoded
+      end
+
+      Her::API.default_api.connection.adapter :test do |stub|
+        stub.get("/users/1") { |env| [200, {}, { :id => 1, :first_name => "Gooby", :last_name => "Pls", :role => {:id => 1, :name => "Admin"} }.to_json] }
+      end
+
+      spawn_model "Foo::User" do
+        has_one :role, class_name:"Foo::Role"
+        attributes :id, :first_name, :last_name
+      end
+      spawn_model "Foo::Role" do
+        attributes :id, :name
+      end
+    end
+
+    it "get user json with admin role" do
+      user = Foo::User.find(1)
+      expect(user.to_params).to eq({ :id => 1, :first_name => "Gooby", :last_name => "Pls", :role => {:id => 1, :name => "Admin"} })
+    end
+  end
 end