Background

Upon continuing a Ruby on Rails project after a few months delay, Aptana Studio’s RadRails editor installed some updates.  I suspect something that  changed in Rails itself (GEM update) caused the error I received.

Error Message

undefined method `include_root_in_json=’ for ActiveRecord::Base:Class (NoMethodError)

Solution

To fix this error rename the config/initializers/new_rails_defaults.rb to config/initializers/new_rails_defaults.rb.bak.

It appears that the old code placed in these files no longer works with ROR 2.0.2.

# These settings change the behavior of Rails 2 apps and will be defaults
# for Rails 3. You can remove this initializer when Rails 3 is released.

# Include Active Record class name as root for JSON serialized output.
ActiveRecord::Base.include_root_in_json = true

# Store the full class name (including module namespace) in STI type column.
ActiveRecord::Base.store_full_sti_class = true

# Use ISO 8601 format for JSON serialized times and dates.
ActiveSupport.use_standard_json_time_format = true

# Don’t escape HTML entities in JSON, leave that for the #json_escape helper.
# if you’re including raw json in an HTML page.
ActiveSupport.escape_html_entities_in_json = false

The file now created in a new project appears as follows:

# These settings change the behavior of Rails 2 apps and will be defaults
# for Rails 3. You can remove this initializer when Rails 3 is released.

if defined?(ActiveRecord)
# Include Active Record class name as root for JSON serialized output.
ActiveRecord::Base.include_root_in_json = true

# Store the full class name (including module namespace) in STI type column.
ActiveRecord::Base.store_full_sti_class = true
end

# Use ISO 8601 format for JSON serialized times and dates.
ActiveSupport.use_standard_json_time_format = true

# Don’t escape HTML entities in JSON, leave that for the #json_escape helper.
# if you’re including raw json in an HTML page.
ActiveSupport.escape_html_entities_in_json = false

Footnotes

See  http://www.hostingrails.com/1461/dbmigrate-undefined-method-include_root_in_json for more help with this error.