fix: support has_many :through pointing at ActiveHash

Closes #239

lib/associations/associations.rb

@@ -2,11 +2,35 @@ module ActiveHash
   module Associations
 
     module ActiveRecordExtensions
-
       def self.extended(base)
         require_relative 'reflection_extensions'
       end
 
+      def has_many(association_id, **options)
+        if options[:through]
+          klass_name = association_id.to_s.classify
+          klass =
+            begin
+              klass_name.constantize
+            rescue StandardError, LoadError
+              nil
+            end
+
+          if klass && klass < ActiveHash::Base
+            define_method(association_id) do
+              join_models = send(options[:through])
+              join_models.flat_map do |join_model|
+                join_model.send(association_id.to_s.singularize)
+              end.uniq
+            end
+
+            return
+          end
+        end
+
+        super
+      end
+
       def belongs_to(name, scope = nil, **options)
         klass_name = options.key?(:class_name) ? options[:class_name] : name.to_s.camelize
         klass =
@@ -117,6 +141,7 @@ def has_many(association_id, options = {})
             klass.where(foreign_key => primary_key_value)
           end
         end
+
         define_method("#{association_id.to_s.underscore.singularize}_ids") do
           public_send(association_id).map(&:id)
         end
@@ -140,7 +165,6 @@ def has_one(association_id, options = {})
       end
 
       def belongs_to(association_id, options = {})
-
         options = {
           :class_name => association_id.to_s.classify,
           :foreign_key => association_id.to_s.foreign_key,
@@ -156,7 +180,6 @@ def belongs_to(association_id, options = {})
         define_method("#{association_id}=") do |new_value|
           attributes[options[:foreign_key].to_sym] = new_value ? new_value.send(options[:primary_key]) : nil
         end
-
       end
     end
 

spec/associations/active_record_extensions_spec.rb

@@ -48,6 +48,7 @@ def define_school_classes
           t.integer :locateable_id
           t.integer :city_id
         end
+
         extend ActiveHash::Associations::ActiveRecordExtensions
       end
 
@@ -58,6 +59,45 @@ def define_school_classes
       define_ephemeral_class(:SchoolStatus, ActiveHash::Base)
     end
 
+    def define_doctor_classes
+      define_ephemeral_class(:Physician, ActiveHash::Base) do
+        include ActiveHash::Associations
+
+        has_many :appointments
+        has_many :patients, through: :appointments
+
+        self.data = [
+          {:id => 1, :name => "ikeda"},
+          {:id => 2, :name => "sato"}
+        ]
+      end
+
+      define_ephemeral_class(:Appointment, ActiveRecord::Base) do
+        establish_connection :adapter => "sqlite3", :database => ":memory:"
+        connection.create_table :appointments, force: true do |t|
+          t.references :physician
+          t.references :patient
+        end
+
+        extend ActiveHash::Associations::ActiveRecordExtensions
+
+        belongs_to :physician
+        belongs_to :patient
+      end
+
+      define_ephemeral_class(:Patient, ActiveRecord::Base) do
+        establish_connection :adapter => "sqlite3", :database => ":memory:"
+        connection.create_table :patients, force: true do |t|
+        end
+
+        extend ActiveHash::Associations::ActiveRecordExtensions
+
+        has_many :appointments
+        has_many :physicians, through: :appointments
+      end
+
+    end
+
     before do
       @ephemeral_classes = []
     end
@@ -152,6 +192,23 @@ def define_school_classes
           author.books.to_a
         end
       end
+
+      describe ":through" do
+        before { define_doctor_classes }
+
+        it "finds ActiveHash records through the join model" do
+          patient = Patient.create!
+
+          physician1 = Physician.first
+          Appointment.create!(physician: physician1, patient: patient)
+          Appointment.create!(physician: physician1, patient: patient)
+
+          physician2 = Physician.last
+          Appointment.create!(physician: physician2, patient: patient)
+
+          expect(patient.physicians).to contain_exactly(physician1, physician2)
+        end
+      end
     end
 
     describe ActiveHash::Associations::ActiveRecordExtensions do
@@ -332,6 +389,5 @@ def define_school_classes
         end
       end
     end
-
   end
 end