Add DSL for association eager-loading

Closes #1325, Closes #1342, Closes #1434, Closes #2649, Refs. #2682

CHANGELOG.md

@@ -4,6 +4,9 @@
 
 [Full Changelog](https://github.com/sferik/rails_admin/compare/v1.0.0...HEAD)
 
+### Added
+- DSL for association eager-loading([#1325](https://github.com/sferik/rails_admin/issues/1325), [#1342](https://github.com/sferik/rails_admin/issues/1342))
+
 
 ## [1.0.0](https://github.com/sferik/rails_admin/tree/v1.0.0) - 2016-09-19
 

app/controllers/rails_admin/main_controller.rb

@@ -120,7 +120,7 @@ def check_for_cancel
     end
 
     def get_collection(model_config, scope, pagination)
-      associations = model_config.list.fields.select { |f| f.type == :belongs_to_association && !f.polymorphic? }.collect { |f| f.association.name }
+      associations = model_config.list.fields.select { |f| f.try(:eager_load?) }.collect { |f| f.association.name }
       options = {}
       options = options.merge(page: (params[Kaminari.config.param_name] || 1).to_i, per: (params[:per] || model_config.list.items_per_page)) if pagination
       options = options.merge(include: associations) unless associations.blank?

lib/rails_admin/config/fields/association.rb

@@ -62,6 +62,10 @@ def association
           association.foreign_key_nullable?
         end
 
+        register_instance_option :eager_load? do
+          !!searchable
+        end
+
         # Reader for the association's child model's configuration
         def associated_model_config
           @associated_model_config ||= RailsAdmin.config(association.klass)

lib/rails_admin/config/fields/types/belongs_to_association.rb

@@ -31,6 +31,10 @@ class BelongsToAssociation < RailsAdmin::Config::Fields::Association
             true
           end
 
+          register_instance_option :eager_load? do
+            true
+          end
+
           def selected_id
             bindings[:object].send(foreign_key)
           end

lib/rails_admin/config/fields/types/polymorphic_association.rb

@@ -45,6 +45,10 @@ class PolymorphicAssociation < RailsAdmin::Config::Fields::Types::BelongsToAssoc
             [children_fields]
           end
 
+          register_instance_option :eager_load? do
+            false
+          end
+
           def associated_collection(type)
             return [] if type.blank?
             config = RailsAdmin.config(type)

spec/controllers/rails_admin/main_controller_spec.rb

@@ -233,6 +233,27 @@ def get(action, params)
     end
   end
 
+  describe '#get_collection' do
+    before do
+      @team = FactoryGirl.create(:team)
+      controller.params = {model_name: 'teams'}
+      RailsAdmin.config Team do
+        field :players do
+          eager_load true
+        end
+      end
+      @model_config = RailsAdmin.config(Team)
+    end
+
+    it 'performs eager-loading for an association field with `eagar_load true`' do
+      scope = double('scope')
+      abstract_model = @model_config.abstract_model
+      allow(@model_config).to receive(:abstract_model).and_return(abstract_model)
+      expect(abstract_model).to receive(:all).with(hash_including(include: [:players]), scope).once
+      controller.send(:get_collection, @model_config, scope, false)
+    end
+  end
+
   describe 'index' do
     it "uses source association's primary key with :compact, not target model's default primary key", skip_mongoid: true do
       class TeamWithNumberedPlayers < Team

spec/integration/basic/list/rails_admin_basic_list_spec.rb

@@ -64,6 +64,7 @@
         FactoryGirl.create(:player, retired: false, injured: true, team: @teams[1]),
         FactoryGirl.create(:player, retired: false, injured: false, team: @teams[1]),
       ]
+      @comment = FactoryGirl.create(:comment, commentable: @players[2])
     end
 
     it 'allows to query on any attribute' do
@@ -270,6 +271,23 @@
       is_expected.to have_no_content(@players[3].name)
     end
 
+    it 'allows to search a has_many attribute over the target table' do
+      RailsAdmin.config Player do
+        list do
+          field PK_COLUMN
+          field :name
+          field :comments do
+            searchable :content
+          end
+        end
+      end
+      visit index_path(model_name: 'player', f: {comments: {'1' => {v: @comment.content}}})
+      is_expected.to have_no_content(@players[0].name)
+      is_expected.to have_no_content(@players[1].name)
+      is_expected.to have_content(@players[2].name)
+      is_expected.to have_no_content(@players[3].name)
+    end
+
     it 'displays base filters when no filters are present in the params' do
       RailsAdmin.config Player do
         list { filters([:name, :team]) }