rails/jbuilder — pull request #105 by DeTeam (2013-03-11 07:37:11+00:00)
Title: Key name from a variable/method

It may be useful to pass keyname for json from somewhere else (look at example below).

```ruby
common_collections_map.each do |key, collection|
json.key! key, collection do |item|
json.call item, :name
end
end
```

common_collections - hash, mapping some name with some common collections (i.e. different types of tags) which should be included in json.