The documentation of `#to_key` (http://api.rubyonrails.org/classes/ActiveModel/Conversion.html#method-i-to_key)
states that it returns `nil` if there are no key attributes. `to_param` needs
to be aware of that fact and return `nil` as well.
Previously it raised the following exception:
```
1) Error:
ConversionTest#test_to_param_returns_nil_if_to_key_is_nil:
NoMethodError: undefined method `join' for nil:NilClass
/Users/senny/Projects/rails/activemodel/lib/active_model/conversion.rb:65:in `to_param'
/Users/senny/Projects/rails/activemodel/test/cases/conversion_test.rb:34:in `block in <class:ConversionTest>'
```
Resolve the following error when running `bundle exec rake guides:generate:html`:
```
/Users/senny/.rbenv/versions/2.0.0-p353/bin/ruby rails_guides.rb
Generating 2_2_release_notes.md as 2_2_release_notes.html
/Users/senny/Projects/rails/guides/rails_guides/helpers.rb:17:in `documents_by_section': uninitialized constant RailsGuides::Helpers::YAML (ActionView::Template::Error)
from /Users/senny/Projects/rails/guides/rails_guides/helpers.rb:32:in `docs_for_menu'
from /Users/senny/Projects/rails/guides/source/layout.html.erb:56:in `block in ___sers_senny__rojects_rails_guides_source_layout_html_erb___3094858039481335962_70118647133480'
from /Users/senny/Projects/rails/guides/source/layout.html.erb:54:in `each'
from /Users/senny/Projects/rails/guides/source/layout.html.erb:54:in `___sers_senny__rojects_rails_guides_source_layout_html_erb___3094858039481335962_70118647133480'
from /Users/senny/Projects/rails/actionview/lib/action_view/template.rb:143:in `block in render'
from /Users/senny/Projects/rails/activesupport/lib/active_support/notifications.rb:161:in `instrument'
from /Users/senny/Projects/rails/actionview/lib/action_view/template.rb:337:in `instrument'
from /Users/senny/Projects/rails/actionview/lib/action_view/template.rb:141:in `render'
from /Users/senny/Projects/rails/actionview/lib/action_view/renderer/template_renderer.rb:61:in `render_with_layout'
from /Users/senny/Projects/rails/actionview/lib/action_view/renderer/template_renderer.rb:47:in `render_template'
from /Users/senny/Projects/rails/actionview/lib/action_view/renderer/template_renderer.rb:17:in `render'
from /Users/senny/Projects/rails/actionview/lib/action_view/renderer/renderer.rb:42:in `render_template'
from /Users/senny/Projects/rails/actionview/lib/action_view/renderer/renderer.rb:23:in `render'
from /Users/senny/Projects/rails/actionview/lib/action_view/helpers/rendering_helper.rb:24:in `render'
from /Users/senny/Projects/rails/guides/rails_guides/markdown.rb:160:in `render_page'
from /Users/senny/Projects/rails/guides/rails_guides/markdown.rb:25:in `render'
from /Users/senny/Projects/rails/guides/rails_guides/generator.rb:205:in `block in generate_guide'
from /Users/senny/Projects/rails/guides/rails_guides/generator.rb:195:in `open'
from /Users/senny/Projects/rails/guides/rails_guides/generator.rb:195:in `generate_guide'
from /Users/senny/Projects/rails/guides/rails_guides/generator.rb:144:in `block in generate_guides'
from /Users/senny/Projects/rails/guides/rails_guides/generator.rb:142:in `each'
from /Users/senny/Projects/rails/guides/rails_guides/generator.rb:142:in `generate_guides'
from /Users/senny/Projects/rails/guides/rails_guides/generator.rb:97:in `generate'
from rails_guides.rb:63:in `<main>'
rake aborted!
Command failed with status (1): [/Users/senny/.rbenv/versions/2.0.0-p353/bi...]
/Users/senny/Projects/rails/guides/Rakefile:11:in `block (3 levels) in <top (required)>'
Tasks: TOP => guides:generate:html
(See full trace by running task with --trace)
```
I did not see in the docs that `button_to` supports not only URLs but paths as well. I documented this functionality with a unit tests and added an example to the docs as well.
Rails currently provides an extension to BigDecimal that redefines how
it is serialized to YAML. However, as noted in #12467, this does not
work as expected. When ActiveSupport is required, BigDecimal YAML
serialization does not maintain the object type. It instead ends up
serializing the number represented by the BigDecimal itself which, when
loaded by YAML later, becomes a Float:
```ruby
require 'yaml'
require 'bigdecimal'
yaml = BigDecimal('13.37').to_yaml
YAML.load(yaml).class
require 'active_support/all'
yaml = BigDecimal('13.37').to_yaml
YAML.load(yaml).class
```
@tenderlove posits that we should deprecate the custom BigDecimal
serialization and let Ruby handle it. For the time being, users who
require this serialization for backwards compatibility can manually
`require 'active_support/core_ext/big_decimal/yaml_conversions'`.
This will close#12467 and deprecate the custom BigDecimal#to_yaml.
Signed-off-by: David Celis <me@davidcel.is>
Since its conception arel was made to be private API of Active Record.
If users want to use arel features directly we should provide a way
using the Active Record API without exposing the arel implementation.
LookupContext is eagerly loaded, and FallbackFileSystemResolver is
referenced at the class level. Just require the resolver from the
eagerly loaded class rather than jumping through autoload hoops
Updated association_basics.md to include how to write migrations for self joins
Update association_basics.md
Corrected the update
Update association_basics.md
Typo fix
Changed :employee to :manager
