Add new in-place partial invocation support

Fixes #266

Author: rwz

lib/jbuilder.rb

@@ -23,6 +23,7 @@ def self.encode(*args, &block)
   end
 
   BLANK = Blank.new
+  NON_ENUMERABLES = [ ::Struct, ::OpenStruct ].to_set
 
   def set!(key, value = BLANK, *args)
     result = if ::Kernel.block_given?
@@ -46,7 +47,7 @@ def set!(key, value = BLANK, *args)
         # { "age": 32 }
         value
       end
-    elsif _mapable_arguments?(value, *args)
+    elsif _is_collection?(value)
       # json.comments @post.comments, :content, :created_at
       # { "comments": [ { "content": "hello", "created_at": "..." }, { "content": "world", "created_at": "..." } ] }
       _scope{ array! value, *args }
@@ -59,8 +60,13 @@ def set!(key, value = BLANK, *args)
     _set_value key, result
   end
 
-  alias_method :method_missing, :set!
-  private :method_missing
+  def method_missing(*args)
+    if ::Kernel.block_given?
+      set! *args, &::Proc.new
+    else
+      set! *args
+    end
+  end
 
   # Specifies formatting to be applied to the key. Passing in a name of a function
   # will cause that function to be called on the key.  So :upcase will upper case
@@ -301,13 +307,17 @@ def _scope
     @attributes, @key_formatter = parent_attributes, parent_formatter
   end
 
-  def _mapable_arguments?(value, *args)
-    value.respond_to?(:map)
+  def _is_collection?(object)
+    _object_respond_to?(object, :map, :count) && NON_ENUMERABLES.none?{ |klass| klass === object }
   end
 
   def _blank?(value=@attributes)
     BLANK == value
   end
+
+  def _object_respond_to?(object, *methods)
+    methods.all?{ |m| object.respond_to?(m) }
+  end
 end
 
 require 'jbuilder/railtie' if defined?(Rails)

lib/jbuilder/jbuilder_template.rb

@@ -35,16 +35,6 @@ def partial!(name_or_options, locals = {})
     _render_partial_with_options options
   end
 
-  def array!(collection = [], *attributes)
-    options = attributes.extract_options!
-
-    if options.key?(:partial)
-      partial! options[:partial], options.merge(collection: collection)
-    else
-      super
-    end
-  end
-
   # Caches the json constructed within the block passed. Has the same signature as the `cache` helper
   # method in `ActionView::Helpers::CacheHelper` and so can be used in the same way.
   #
@@ -78,7 +68,34 @@ def cache_if!(condition, *args)
     condition ? cache!(*args, &::Proc.new) : yield
   end
 
-  protected
+  def array!(collection = [], *attributes)
+    options = attributes.extract_options!
+
+    if options.key?(:partial)
+      partial! options[:partial], options.merge(collection: collection)
+    else
+      super
+    end
+  end
+
+  def set!(name, object = BLANK, *args)
+    options = args.first
+
+    return super unless _partial_options?(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
+
+    super name, value
+  end
+
+  private
 
   def _render_partial_with_options(options)
     options.reverse_merge! locals: {}
@@ -111,8 +128,6 @@ def _cache_key(key, options)
     ::ActiveSupport::Cache.expand_cache_key(key, :jbuilder)
   end
 
-  private
-
   def _fragment_name_with_digest(key, options)
     if @context.respond_to?(:cache_fragment_name)
       # Current compatibility, fragment_name_with_digest is private again and cache_fragment_name
@@ -126,10 +141,8 @@ def _fragment_name_with_digest(key, options)
     end
   end
 
-  def _mapable_arguments?(value, *args)
-    return true if super
-    options = args.last
-    ::Hash === options && options.key?(:as)
+  def _partial_options?(options)
+    ::Hash === options && options.key?(:as) && options.key?(:partial)
   end
 end
 

test/jbuilder_template_test.rb

@@ -8,9 +8,9 @@
 BLOG_POST_PARTIAL = <<-JBUILDER
   json.extract! blog_post, :id, :body
   json.author do
-    name = blog_post.author_name.split(nil, 2)
-    json.first_name name[0]
-    json.last_name  name[1]
+    first_name, last_name = blog_post.author_name.split(nil, 2)
+    json.first_name first_name
+    json.last_name last_name
   end
 JBUILDER
 
@@ -338,4 +338,16 @@ def assert_collection_rendered(result, context = nil)
 
     assert_equal Rails.cache.inspect[/entries=(\d+)/, 1], "0"
   end
+
+  test "invokes templates via params via set!" do
+    @post = BLOG_POST_COLLECTION.first
+
+    result = jbuild(<<-JBUILDER)
+      json.post @post, partial: "blog_post", as: :blog_post
+    JBUILDER
+
+    assert_equal 1, result["post"]["id"]
+    assert_equal "post body 1", result["post"]["body"]
+    assert_equal "David", result["post"]["author"]["first_name"]
+  end
 end

test/jbuilder_test.rb

@@ -13,9 +13,7 @@ def initialize(collection)
     @collection = collection
   end
 
-  def map(&block)
-    @collection.map(&block)
-  end
+  delegate :map, :count, to: :@collection
 end
 
 class VeryBasicWrapper < BasicObject