Allow to skip array! iterations by calling next

README.md

@@ -80,19 +80,26 @@ end
 Top level arrays can be handled directly.  Useful for index and other collection actions.
 
 ``` ruby
-# @people = People.all
-json.array! @people do |person|
-  json.name person.name
-  json.age calculate_age(person.birthday)
+# @comments = @post.comments
+
+json.array! @comments do |comment|
+  next if comment.marked_as_spam_by?(current_user)
+
+  json.body comment.body
+  json.author do
+    json.first_name comment.author.first_name
+    json.last_name comment.author.last_name
+  end
 end
 
-# => [ { "name": "David", "age": 32 }, { "name": "Jamie", "age": 31 } ]
+# => [ { "body": "great post...", "author": { "first_name": "Joe", "last_name": "Bloe" }} ]
 ```
 
 You can also extract attributes from array directly.
 
 ``` ruby
 # @people = People.all
+
 json.array! @people, :id, :name
 
 # => [ { "id": 1, "name": "David" }, { "id": 2, "name": "Jamie" } ]

lib/jbuilder.rb

@@ -260,10 +260,11 @@ def _merge_block(key, &block)
   end
 
   def _read(key, default = nil)
-    @attributes.fetch(_key(key)){ default }
+    _blank? ? default : @attributes.fetch(_key(key)){ default }
   end
 
   def _write(key, value)
+    @attributes = {} if _blank?
     @attributes[_key(key)] = value
   end
 
@@ -280,12 +281,12 @@ def _set_value(key, value)
   def _map_collection(collection)
     collection.map do |element|
       _scope{ yield element }
-    end
+    end - [BLANK]
   end
 
   def _scope
     parent_attributes, parent_formatter = @attributes, @key_formatter
-    @attributes = {}
+    @attributes = BLANK
     yield
     @attributes
   ensure
@@ -308,6 +309,10 @@ def _merge_values(attributes, hash_or_array)
 
     attributes
   end
+
+  def _blank?
+    BLANK == @attributes
+  end
 end
 
 require 'jbuilder/jbuilder_template' if defined?(ActionView::Template)

test/jbuilder_test.rb

@@ -373,6 +373,20 @@ class JbuilderTest < ActiveSupport::TestCase
     assert_equal 'world', result.second['content']
   end
 
+  test 'it allows using next in array block to skip value' do
+    comments = [ Comment.new('hello', 1), Comment.new('skip', 2), Comment.new('world', 3) ]
+    result = jbuild do |json|
+      json.array! comments do |comment|
+        next if comment.id == 2
+        json.content comment.content
+      end
+    end
+
+    assert_equal 2, result.length
+    assert_equal 'hello', result.first['content']
+    assert_equal 'world', result.second['content']
+  end
+
   test 'extract attributes directly from array' do
     comments = [ Comment.new('hello', 1), Comment.new('world', 2) ]