Add implicit partial rendering for AM::Models

Fixes rails#265

Appraisals

@@ -1,34 +1,40 @@
 appraise "rails-3-0" do
   gem "test-unit"
-  gem "railties",   "~> 3.0.0"
-  gem "actionpack", "~> 3.0.0"
+  gem "railties",    "~> 3.0.0"
+  gem "actionpack",  "~> 3.0.0"
+  gem "activemodel", "~> 3.0.0"
 end
 
 appraise "rails-3-1" do
   gem "test-unit"
-  gem "railties",   "~> 3.1.0"
-  gem "actionpack", "~> 3.1.0"
+  gem "railties",    "~> 3.1.0"
+  gem "actionpack",  "~> 3.1.0"
+  gem "activemodel", "~> 3.1.0"
 end
 
 appraise "rails-3-2" do
   gem "test-unit"
-  gem "railties",   "~> 3.2.0"
-  gem "actionpack", "~> 3.2.0"
+  gem "railties",    "~> 3.2.0"
+  gem "actionpack",  "~> 3.2.0"
+  gem "activemodel", "~> 3.2.0"
 end
 
 appraise "rails-4-0" do
-  gem "railties",   "~> 4.0.0"
-  gem "actionpack", "~> 4.0.0"
+  gem "railties",    "~> 4.0.0"
+  gem "actionpack",  "~> 4.0.0"
+  gem "activemodel", "~> 4.0.0"
 end
 
 appraise "rails-4-1" do
-  gem "railties",   "~> 4.1.0"
-  gem "actionpack", "~> 4.1.0"
+  gem "railties",    "~> 4.1.0"
+  gem "actionpack",  "~> 4.1.0"
+  gem "activemodel", "~> 4.1.0"
 end
 
 appraise "rails-4-2" do
-  gem "railties",   "~> 4.2.0"
-  gem "actionpack", "~> 4.2.0"
+  gem "railties",    "~> 4.2.0"
+  gem "actionpack",  "~> 4.2.0"
+  gem "activemodel", "~> 4.2.0"
 end
 
 appraise "rails-edge" do

gemfiles/rails_3_0.gemfile

@@ -9,5 +9,6 @@ gem "pry"
 gem "test-unit"
 gem "railties", "~> 3.0.0"
 gem "actionpack", "~> 3.0.0"
+gem "activemodel", "~> 3.0.0"
 
 gemspec :path => "../"

gemfiles/rails_3_1.gemfile

@@ -9,5 +9,6 @@ gem "pry"
 gem "test-unit"
 gem "railties", "~> 3.1.0"
 gem "actionpack", "~> 3.1.0"
+gem "activemodel", "~> 3.1.0"
 
 gemspec :path => "../"

gemfiles/rails_3_2.gemfile

@@ -9,5 +9,6 @@ gem "pry"
 gem "test-unit"
 gem "railties", "~> 3.2.0"
 gem "actionpack", "~> 3.2.0"
+gem "activemodel", "~> 3.2.0"
 
 gemspec :path => "../"

gemfiles/rails_4_0.gemfile

@@ -8,5 +8,6 @@ gem "appraisal"
 gem "pry"
 gem "railties", "~> 4.0.0"
 gem "actionpack", "~> 4.0.0"
+gem "activemodel", "~> 4.0.0"
 
 gemspec :path => "../"

gemfiles/rails_4_1.gemfile

@@ -8,5 +8,6 @@ gem "appraisal"
 gem "pry"
 gem "railties", "~> 4.1.0"
 gem "actionpack", "~> 4.1.0"
+gem "activemodel", "~> 4.1.0"
 
 gemspec :path => "../"

gemfiles/rails_4_2.gemfile

@@ -8,5 +8,6 @@ gem "appraisal"
 gem "pry"
 gem "railties", "~> 4.2.0"
 gem "actionpack", "~> 4.2.0"
+gem "activemodel", "~> 4.2.0"
 
 gemspec :path => "../"

lib/jbuilder/jbuilder_template.rb

@@ -11,28 +11,15 @@ class << self
 
   def initialize(context, *args)
     @context = context
-    super(*args)
+    super *args
   end
 
-  def partial!(name_or_options, locals = {})
-    case name_or_options
-    when ::Hash
-      # partial! partial: 'name', foo: 'bar'
-      options = name_or_options
+  def partial!(*args)
+    if args.one? && _is_active_model?(args.first)
+      _render_active_model_partial args.first
     else
-      # partial! 'name', locals: {foo: 'bar'}
-      if locals.one? && (locals.keys.first == :locals)
-        options = locals.merge(partial: name_or_options)
-      else
-        options = { partial: name_or_options, locals: locals }
-      end
-      # partial! 'name', foo: 'bar'
-      as = locals.delete(:as)
-      options[:as] = as if as.present?
-      options[:collection] = locals[:collection] if locals.key?(:collection)
+      _render_explicit_partial *args
     end
-
-    _render_partial_with_options options
   end
 
   # Caches the json constructed within the block passed. Has the same signature as the `cache` helper
@@ -81,18 +68,11 @@ def array!(collection = [], *args)
   def set!(name, object = BLANK, *args)
     options = args.first
 
-    return super unless args.one? && _partial_options?(options)
-
-    value = if object.nil?
-      []
-    elsif _is_collection?(object)
-      _scope{ _render_partial_with_options options.merge(collection: object) }
+    if args.one? && _partial_options?(options)
+      _set_inline_partial name, object, options
     else
-      locals = ::Hash[options[:as], object]
-      _scope{ _render_partial options.merge(locals: locals) }
+      super
     end
-
-    super name, value
   end
 
   private
@@ -144,6 +124,48 @@ def _fragment_name_with_digest(key, options)
   def _partial_options?(options)
     ::Hash === options && options.key?(:as) && options.key?(:partial)
   end
+
+  def _is_active_model?(object)
+    object.class.respond_to?(:model_name) && object.respond_to?(:to_partial_path)
+  end
+
+  def _set_inline_partial(name, object, options)
+    value = if object.nil?
+      []
+    elsif _is_collection?(object)
+      _scope{ _render_partial_with_options options.merge(collection: object) }
+    else
+      locals = ::Hash[options[:as], object]
+      _scope{ _render_partial options.merge(locals: locals) }
+    end
+
+    set! name, value
+  end
+
+  def _render_explicit_partial(name_or_options, locals = {})
+    case name_or_options
+    when ::Hash
+      # partial! partial: 'name', foo: 'bar'
+      options = name_or_options
+    else
+      # partial! 'name', locals: {foo: 'bar'}
+      if locals.one? && (locals.keys.first == :locals)
+        options = locals.merge(partial: name_or_options)
+      else
+        options = { partial: name_or_options, locals: locals }
+      end
+      # partial! 'name', foo: 'bar'
+      as = locals.delete(:as)
+      options[:as] = as if as.present?
+      options[:collection] = locals[:collection] if locals.key?(:collection)
+    end
+
+    _render_partial_with_options options
+  end
+
+  def _render_active_model_partial(object)
+    @context.render object, json: self
+  end
 end
 
 class JbuilderHandler

test/jbuilder_template_test.rb

@@ -1,5 +1,6 @@
 require "test_helper"
 require "mocha/setup"
+require "active_model"
 require "action_view"
 require "action_view/testing/resolvers"
 require "active_support/cache"
@@ -18,6 +19,22 @@
   json.extract! collection, :id, :name
 JBUILDER
 
+RACER_PARTIAL = <<-JBUILDER
+  json.extract! racer, :id, :name
+JBUILDER
+
+class Racer
+  extend ActiveModel::Naming
+  include ActiveModel::Conversion
+
+  def initialize(id, name)
+    @id, @name = id, name
+  end
+
+  attr_reader :id, :name
+end
+
+
 BlogPost = Struct.new(:id, :body, :author_name)
 Collection = Struct.new(:id, :name)
 blog_authors = [ "David Heinemeier Hansson", "Pavel Pravosud" ].cycle
@@ -29,6 +46,7 @@
 PARTIALS = {
   "_partial.json.jbuilder"  => "foo ||= 'hello'; json.content foo",
   "_blog_post.json.jbuilder" => BLOG_POST_PARTIAL,
+  "racers/_racer.json.jbuilder" => RACER_PARTIAL,
   "_collection.json.jbuilder" => COLLECTION_PARTIAL
 }
 
@@ -350,4 +368,16 @@ def assert_collection_rendered(result, context = nil)
     assert_equal "post body 1", result["post"]["body"]
     assert_equal "David", result["post"]["author"]["first_name"]
   end
+
+  test "invokes templates implicitly for ActiveModel objects" do
+    @racer = Racer.new(123, "Chris Harris")
+
+    result = jbuild(<<-JBUILDER)
+      json.partial! @racer
+    JBUILDER
+
+    assert_equal %w[id name], result.keys
+    assert_equal 123, result["id"]
+    assert_equal "Chris Harris", result["name"]
+  end
 end