Allow has_one nil association (#48)

* Allow has_one nil association

* add test for when has_one returns nil

* modify has_one extension method, add active record test

* Use try operator to support old rubies

Author: jeremyjung

lib/extensions/has_one.rb

@@ -9,7 +9,7 @@ def self.define_accessors(mixin, reflection)
     name = reflection.name
     mixin.class_eval <<-CODE, __FILE__, __LINE__ + 1
       def #{name.to_s}_id
-        association(:#{name}).reader.id
+        association(:#{name}).reader.try(:id)
       end
     CODE
   end

spec/lib/extensions/active_record_spec.rb

@@ -29,8 +29,10 @@
     # Insert records
     @account_id = 2
     @supplier_id = 1
+    @supplier_id_without_account = 3
     db.execute_batch <<-SQL
-      insert into suppliers values ('Supplier1', #{@supplier_id});
+      insert into suppliers values ('Supplier1', #{@supplier_id}),
+                                   ('SupplierWithoutAccount', #{@supplier_id_without_account});
       insert into accounts values ('Dollar Account', #{@account_id}, #{@supplier_id});
     SQL
   end
@@ -58,6 +60,10 @@ class Account < ActiveRecord::Base
       expect(Supplier.first.account_id).to eq @account_id
     end
 
+    it 'has account_id method return nil if account not present' do
+      expect(Supplier.find(@supplier_id_without_account).account_id).to eq nil
+    end
+
   end
 
   # Clean up DB

spec/lib/object_serializer_spec.rb

@@ -69,6 +69,13 @@
       expect(serializable_hash['data']['relationships']['owner']['data']).to be nil
     end
 
+    it 'returns correct json when has_one returns nil' do
+      supplier.account_id = nil
+      json = SupplierSerializer.new(supplier).serialized_json
+      serializable_hash = JSON.parse(json)
+      expect(serializable_hash['data']['relationships']['account']['data']).to be nil
+    end
+
     it 'returns correct json when serializing []' do
       json = MovieSerializer.new([]).serialized_json
       serializable_hash = JSON.parse(json)

spec/shared/contexts/movie_context.rb

@@ -36,6 +36,22 @@ class MovieType
       attr_accessor :id, :name
     end
 
+    class Supplier
+      attr_accessor :id, :account_id
+
+      def account
+        if account_id
+          a = Account.new
+          a.id = account_id
+          a
+        end
+      end
+    end
+
+    class Account
+      attr_accessor :id
+    end
+
     # serializers
     class MovieSerializer
       include FastJsonapi::ObjectSerializer
@@ -79,6 +95,18 @@ class MovieTypeSerializer
       set_type :movie_type
       attributes :name
     end
+
+    class SupplierSerializer
+      include FastJsonapi::ObjectSerializer
+      set_type :supplier
+      has_one :account
+    end
+
+    class AccountSerializer
+      include FastJsonapi::ObjectSerializer
+      set_type :account
+      belongs_to :supplier
+    end
   end
 
 
@@ -151,6 +179,13 @@ class MovieSerializer
     m
   end
 
+  let(:supplier) do
+    s = Supplier.new
+    s.id = 1
+    s.account_id = 1
+    s
+  end
+
   def build_movies(count)
     count.times.map do |i|
       m = Movie.new