Added support for :primary_key in sorting on relationships

lib/jsonapi/active_relation_resource_finder.rb

@@ -434,10 +434,11 @@ def _build_joins(associations)
         associations.inject do |prev, current|
           prev_table_name = _join_table_name(prev)
           curr_table_name = _join_table_name(current)
+          relationship_primary_key = current.options.fetch(:primary_key, "id")
           if current.belongs_to?
-            joins << "LEFT JOIN #{current.table_name} AS #{curr_table_name} ON #{curr_table_name}.id = #{prev_table_name}.#{current.foreign_key}"
+            joins << "LEFT JOIN #{current.table_name} AS #{curr_table_name} ON #{curr_table_name}.#{relationship_primary_key} = #{prev_table_name}.#{current.foreign_key}"
           else
-            joins << "LEFT JOIN #{current.table_name} AS #{curr_table_name} ON #{curr_table_name}.#{current.foreign_key} = #{prev_table_name}.id"
+            joins << "LEFT JOIN #{current.table_name} AS #{curr_table_name} ON #{curr_table_name}.#{current.foreign_key} = #{prev_table_name}.#{relationship_primary_key}"
           end
 
           current

test/controllers/widget_controller_test.rb

@@ -0,0 +1,47 @@
+require File.expand_path('../../test_helper', __FILE__)
+
+def set_content_type_header!
+  @request.headers['Content-Type'] = JSONAPI::MEDIA_TYPE
+end
+
+class WidgetsControllerTest < ActionController::TestCase
+  def teardown
+    Widget.delete_all
+    Indicator.delete_all
+    Agency.delete_all
+  end
+
+  def test_fetch_widgets_sort_by_agency_name
+    agency_1 = Agency.create! name: 'beta'
+    agency_2 = Agency.create! name: 'alpha'
+    indicator_1 = Indicator.create! import_id: 'foobar', name: 'bar', agency: agency_1
+    indicator_2 = Indicator.create! import_id: 'foobar2', name: 'foo', agency: agency_2
+    Widget.create! name: 'bar', indicator: indicator_1
+    widget = Widget.create! name: 'foo', indicator: indicator_2
+    assert_cacheable_get :index, params: {sort: 'indicator.agency.name'}
+    assert_response :success
+    assert_equal widget.id.to_s, json_response['data'].first['id']
+  end
+end
+
+class IndicatorsControllerTest < ActionController::TestCase
+  def teardown
+    Widget.delete_all
+    Indicator.delete_all
+    Agency.delete_all
+  end
+
+  def test_fetch_indicators_sort_by_widgets_name
+    agency = Agency.create! name: 'test'
+    indicator_1 = Indicator.create! import_id: 'bar', name: 'bar', agency: agency
+    indicator_2 = Indicator.create! import_id: 'foo', name: 'foo', agency: agency
+    Widget.create! name: 'omega', indicator: indicator_1
+    Widget.create! name: 'beta', indicator: indicator_1
+    Widget.create! name: 'alpha', indicator: indicator_2
+    Widget.create! name: 'zeta', indicator: indicator_2
+    assert_cacheable_get :index, params: {sort: 'widgets.name'}
+    assert_response :success
+    assert_equal indicator_2.id.to_s, json_response['data'].first['id']
+    assert_equal 2, json_response['data'].size
+  end
+end

test/fixtures/active_record.rb

@@ -341,13 +341,14 @@
 
   create_table :indicators, force: true do |t|
     t.string :name
+    t.string :import_id
     t.integer :agency_id, null: false
     t.timestamps null: false
   end
 
   create_table :widgets, force: true do |t|
     t.string :name
-    t.integer :indicator_id, null: false
+    t.string :indicator_import_id, null: false
     t.timestamps null: false
   end
 
@@ -724,11 +725,11 @@ class Agency < ActiveRecord::Base
 
 class Indicator < ActiveRecord::Base
   belongs_to :agency
-  has_many :widgets
+  has_many :widgets, primary_key: :import_id, foreign_key: :indicator_import_id
 end
 
 class Widget < ActiveRecord::Base
-  belongs_to :indicator
+  belongs_to :indicator, primary_key: :import_id, foreign_key: :indicator_import_id
 end
 
 class Robot < ActiveRecord::Base
@@ -2046,7 +2047,7 @@ class AgencyResource < JSONAPI::Resource
 class IndicatorResource < JSONAPI::Resource
   attributes :name
   has_one :agency
-  has_many :widgets
+  has_many :widgets, foreign_key: :indicator_import_id, primary_key: :import_id
 
   def self.sortable_fields(_context = nil)
     super + [:'widgets.name']
@@ -2055,7 +2056,7 @@ def self.sortable_fields(_context = nil)
 
 class WidgetResource < JSONAPI::Resource
   attributes :name
-  has_one :indicator
+  has_one :indicator, foreign_key: :indicator_import_id, primary_key: :import_id
 
   def self.sortable_fields(_context = nil)
     super + [:'indicator.agency.name']

test/unit/resource/active_relation_resource_finder_test.rb

@@ -4,7 +4,7 @@ class ARPostResource < JSONAPI::Resource
   model_name 'Post'
   attribute :headline, delegate: :title
   has_one :author
-  has_many :tags
+  has_many :tags, primary_key: :tags_import_id
 end
 
 class ActiveRelationResourceFinderTest < ActiveSupport::TestCase