restore 2.x config loading behavior

.rubocop.yml

@@ -115,10 +115,10 @@ Metrics/CyclomaticComplexity:
 
 Metrics/MethodLength:
   CountComments: false
-  Max: 29 # TODO: Lower to 15
+  Max: 30 # TODO: Lower to 15
 
 Metrics/ModuleLength:
-  Max: 217 # TODO: Lower to 100
+  Max: 249 # TODO: Lower to 100
 
 Metrics/ParameterLists:
   Max: 8 # TODO: Lower to 4

lib/rails_admin.rb

@@ -29,7 +29,7 @@ def self.config(entity = nil, &block)
     if entity
       RailsAdmin::Config.model(entity, &block)
     elsif block_given?
-      RailsAdmin::Config.apply(&block)
+      RailsAdmin::Config.apply_core(&block)
     else
       RailsAdmin::Config
     end

lib/rails_admin/adapters/mongoid/extension.rb

@@ -11,9 +11,7 @@ module Extension
           self.nested_attributes_options = {}
           class << self
             def rails_admin(&block)
-              RailsAdmin.config do |config|
-                config.model(self, &block)
-              end
+              RailsAdmin.config(self, &block)
             end
 
             alias_method :accepts_nested_attributes_for_without_rails_admin, :accepts_nested_attributes_for

lib/rails_admin/config.rb

@@ -23,8 +23,12 @@ module Config
     DEFAULT_CURRENT_USER = proc {}
 
     # Variables to track initialization process
-    @initialized = false
-    @deferred_blocks = []
+    @initialized_core = false
+    @initializing_core = false
+    @deferred_core_blocks = []
+    @initialized_models = false
+    @initializing_models = false
+    @deferred_model_blocks = []
 
     class << self
       # Application title, can be an array of two elements
@@ -85,19 +89,42 @@ class << self
       # Set where RailsAdmin fetches JS/CSS from, defaults to :sprockets
       attr_writer :asset_source
 
-      # Finish initialization by executing deferred configuration blocks
-      def initialize!
-        @deferred_blocks.each { |block| block.call(self) }
-        @deferred_blocks.clear
-        @initialized = true
+      # Finish initialization by executing deferred non-model configuration blocks
+      def initialize_core!
+        return if @initializing_core
+
+        @initializing_core = true
+        @deferred_core_blocks.each { |block| block.call(self) }
+        @deferred_core_blocks.clear
+        @initialized_core = true
+      end
+
+      # Evaluate the given non-model block either immediately or lazily, based on initialization status.
+      def apply_core(&block)
+        if @initialized_core
+          yield(self)
+        else
+          @deferred_core_blocks << block
+        end
       end
 
-      # Evaluate the given block either immediately or lazily, based on initialization status.
-      def apply(&block)
-        if @initialized
+      # Finish initialization by executing deferred model configuration blocks
+      def initialize_models!
+        return if @initializing_models
+
+        initialize_core!
+        @initializing_models = true
+        @deferred_model_blocks.each { |block| block.call(self) }
+        @deferred_model_blocks.clear
+        @initialized_models = true
+      end
+
+      # Evaluate the given model block either immediately or lazily, based on initialization status.
+      def apply_model(&block)
+        if @initialized_models
           yield(self)
         else
-          @deferred_blocks << block
+          @deferred_model_blocks << block
         end
       end
 
@@ -226,6 +253,7 @@ def default_search_operator=(operator)
 
       # pool of all found model names from the whole application
       def models_pool
+        initialize_models!
         (viable_models - excluded_models.collect(&:to_s)).uniq.sort
       end
 
@@ -238,7 +266,7 @@ def models_pool
       #
       # If a block is given it is evaluated in the context of configuration instance.
       #
-      # Returns given model's configuration
+      # Otherwise returns given model's configuration.
       #
       # @see RailsAdmin::Config.registry
       def model(entity, &block)
@@ -254,9 +282,24 @@ def model(entity, &block)
             entity.class.name.to_sym
           end
 
-        @registry[key] ||= RailsAdmin::Config::Model.new(entity)
-        @registry[key].instance_eval(&block) if block && @registry[key].abstract_model
-        @registry[key]
+        # When a block is provided defer evaluation until initialize so that:
+        #
+        # 1) performing configuration in the initializer does not attempt to
+        #    autoload model classes, and
+        # 2) model config blocks run after models are fully loaded and
+        #    associations are defined.
+        #
+        # Do not defer when called without a block as the model must be returned.
+        if block
+          RailsAdmin::Config.apply_model do
+            m = model(entity)
+            m.instance_eval(&block) if @registry[key].abstract_model
+          end
+          nil
+        else
+          initialize_models!
+          @registry[key] ||= RailsAdmin::Config::Model.new(entity)
+        end
       end
 
       def asset_source
@@ -318,6 +361,10 @@ def models
       #
       # @see RailsAdmin::Config.registry
       def reset
+        @initialized_core = @initializing_core = false
+        @deferred_core_blocks.clear
+        @initialized_models = @initializing_models = false
+        @deferred_model_blocks.clear
         @compact_show_view = true
         @browser_validations = true
         @authenticate = nil
@@ -356,10 +403,9 @@ def reset_model(model)
 
       # Perform reset, then load RailsAdmin initializer again
       def reload!
-        @initialized = false
         reset
         load RailsAdmin::Engine.config.initializer_path
-        initialize!
+        initialize_core!
       end
 
       # Get all models that are configured as visible sorted by their weight and label.

lib/rails_admin/engine.rb

@@ -68,7 +68,7 @@ class Engine < Rails::Engine
         ERROR
       end
 
-      RailsAdmin::Config.initialize!
+      RailsAdmin::Config.initialize_core!
 
       # Force route reload, since it doesn't reflect RailsAdmin action configuration yet
       app.reload_routes!

spec/dummy_app/config/initializers/rails_admin.rb

@@ -2,7 +2,7 @@
 
 RailsAdmin.config do |c|
   c.asset_source = CI_ASSET
-  c.model 'Team' do
+  c.model Team do
     include_all_fields
     field :color, :color
   end

spec/rails_admin/config_spec.rb

@@ -327,6 +327,24 @@ class TestController < ActionController::Base; end
       end
     end
 
+    context 'when a block is not provided' do
+      let(:model) { described_class.model(Team) }
+      it 'returns the model config' do
+        expect(model).to be_a(RailsAdmin::Config::Model)
+      end
+    end
+
+    context 'when a block is provided' do
+      let(:model) do
+        described_class.model(Team) do
+          field :fans
+        end
+      end
+      it 'does not return the model config' do
+        expect(model).to be_nil
+      end
+    end
+
     context 'when model expanded' do
       before do
         described_class.model(Team) do
@@ -377,40 +395,44 @@ class TestController < ActionController::Base; end
     end
   end
 
-  describe '.apply' do
-    subject { RailsAdmin::Config.apply(&block) }
+  describe '.apply_core' do
+    subject { RailsAdmin::Config.apply_core(&block) }
     let(:block) do
       proc do |config|
         config.model Team do
           register_instance_option('parameter') # an arbitrary instance method we can spy on
         end
       end
     end
-    before { RailsAdmin::Config.instance_variable_set(:@initialized, false) }
-    after do
-      RailsAdmin::Config.instance_variable_set(:@initialized, true)
-      RailsAdmin::Config.instance_variable_set(:@deferred_blocks, [])
-    end
+    after { RailsAdmin::Config.reset }
 
     it "doesn't evaluate the block immediately" do
       expect_any_instance_of(RailsAdmin::Config::Model).not_to receive(:register_instance_option)
       subject
     end
 
-    it 'evaluates block when initialize! is finished' do
+    it "doesn't evaluate the block when initialize_core! is finished" do
+      expect_any_instance_of(RailsAdmin::Config::Model).not_to receive(:register_instance_option).with('parameter')
+      subject
+      RailsAdmin::Config.initialize_core!
+    end
+
+    it 'evaluates block when initialize_models! is finished' do
       expect_any_instance_of(RailsAdmin::Config::Model).to receive(:register_instance_option).with('parameter')
       subject
-      RailsAdmin::Config.initialize!
+      RailsAdmin::Config.initialize_models!
     end
 
     it 'evaluates config block only once' do
       expect_any_instance_of(RailsAdmin::Config::Model).to receive(:register_instance_option).once.with('parameter')
       subject
-      RailsAdmin::Config.initialize!
-      RailsAdmin::Config.initialize!
+      RailsAdmin::Config.initialize_models!
+      RailsAdmin::Config.initialize_models!
     end
 
     context 'with a non-existent class' do
+      before { RailsAdmin::Config.reset }
+
       let(:block) do
         proc do |config|
           config.model UnknownClass do
@@ -445,6 +467,11 @@ class TestController < ActionController::Base; end
       expect(RailsAdmin::Config.model(Team).fields.find { |f| f.name == :color }.type).to eq :color
     end
 
+    it 'does not immediately apply model configuration' do
+      expect(RailsAdmin::Config).not_to receive(:initialize_models!)
+      RailsAdmin::Config.reload!
+    end
+
     it "applies the initializer's configuration first, then models' configurations" do
       # simulate the situation that Team model is loaded in the middle of processing RailsAdmin initializer
       allow_any_instance_of(RailsAdmin::Config::Model).to receive(:include_all_fields).and_wrap_original do |method|

spec/spec_helper.rb

@@ -93,6 +93,7 @@
     DatabaseCleaner.start
     RailsAdmin::Config.reset
     RailsAdmin::Config.asset_source = CI_ASSET
+    RailsAdmin::Config.initialize_core!
   end
 
   config.after(:each) do