RailsConf Europe 2008 - Ian White wrote resources_controller in the beginning of 2007 to DRY up RESTful controllers. In its first iteration it simplified controllers by providing CRUD actions, and loading enclosing resources.

1. Writing resources_controller
Discovering REST patterns in Rails
Ian White ian.w.white@gmail.com @ Argument from Design ardes.com

2. What I’ll cover
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3. What I’ll cover
 Example of RESTful app in vanilla Rails
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4. What I’ll cover
 Example of RESTful app in vanilla Rails
 How was that experience? Where did we have to
repeat ourselves?
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5. What I’ll cover
 Example of RESTful app in vanilla Rails
 How was that experience? Where did we have to
repeat ourselves?
 Plugins to the rescue!
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6. What I’ll cover
 Example of RESTful app in vanilla Rails
 How was that experience? Where did we have to
repeat ourselves?
 Plugins to the rescue!
 resources_controller
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7. What I’ll cover
 Example of RESTful app in vanilla Rails
 How was that experience? Where did we have to
repeat ourselves?
 Plugins to the rescue!
 resources_controller
 Benefits of abstraction
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8. What I’ll cover
 Example of RESTful app in vanilla Rails
 How was that experience? Where did we have to
repeat ourselves?
 Plugins to the rescue!
 resources_controller
 Benefits of abstraction
 Where to next?
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9. REST on Rails
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10. REST on Rails
 Lets look at what’s involved in creating a simple
RESTful app using Rails
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11. REST on Rails
 Lets look at what’s involved in creating a simple
RESTful app using Rails
 We’ll then look at adding features
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12. Video sharing app
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13. Video sharing app
 Users can contribute Videos
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14. Video sharing app
 Users can contribute Videos
 Videos can be categorised in many Categories
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15. Video sharing app
class User < ActiveRecord::Base
 has_manycan contribute Videos
Users :videos
end
 Videos can be categorised in many Categories
class Categorisation < ActiveRecord::Base
belongs_to :video
belongs_to :category
end
class Category < ActiveRecord::Base
has_many :categorisations
has_many :videos, :through => :categorisations
end
class Video
belongs_to :user
has_many :categorisations
has_many :categories, :through => :categorisations
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end

16. Video sharing app
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17. Video sharing app
 Our API?
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18. Video sharing app
 Our API?
 Lets define the URLs
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19. Video sharing app
 Our API?
 Lets define the URLs
 we want to see all videos: /videos
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20. Video sharing app
 Our API?
 Lets define the URLs
 we want to see all videos: /videos
 we want to see all categories: /categories
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21. Video sharing app
 Our API?
 Lets define the URLs
 we want to see all videos: /videos
 we want to see all categories: /categories
 we want to look at videos in the context of one of their
categories: /categories/:category_id/videos/:id
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22. Video sharing app
 Our API?
 Lets define the URLs
 we want to see all videos: /videos
 we want to see all categories: /categories
 we want to look at videos in the context of one of their
categories: /categories/:category_id/videos/:id
 WAIT! does this violate some community norm about
nesting?
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23. Video sharing app
 Our API?
 Lets define the URLs
 we want to see all videos: /videos
 we want to see all categories: /categories
 we want to look at videos in the context of one of their
categories: /categories/:category_id/videos/:id
 WAIT! does this violate some community norm about
nesting?
 No - in this case, it’s necessary, because videos can
be categorised in many categories, and because we
just want to show the video in the context of a category
that the user has selected.
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24. Video sharing app
 Our API?
 Lets define the URLs
 we want to see all videos: /videos
 we want to see all categories: /categories
 we want to look at videos in the context of one of their
categories: /categories/:category_id/videos/:id
 WAIT! does this violate some community norm about
map.resources :videos
nesting?
 No - in this case, it’s necessary, because videos can
map.resources in:categories and because we
be categorised many categories, do |category|
category.resources in the context of a category
just want to show the video :videos
that the user has selected.
end
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25. Video sharing app
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26. Video sharing app
 Because this is a community site, lets not have admin
namespaced controllers just yet
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27. Video sharing app
 Because this is a community site, lets not have admin
namespaced controllers just yet
 We want users to be able submit videos in the context
of a category, and have that categorisation
automatically applied
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28. Video sharing app
 Because this is a community site, lets not have admin
namespaced controllers just yet
 We want users to be able submit videos in the context
of a category, and have that categorisation
automatically applied
 What controllers do we need?
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29. Video sharing app
 Because this is a community site, lets not have admin
namespaced controllers just yet
class  We want users to be able submit videos in the context
VideosController < ApplicationController
of a category, and have that categorisation
# GET /videos, GET /videos.xml
automatically applied
def index
 What= Video.find(:all)
@videos
controllers do we need?
respond_to do |format|
format.html # index.html.erb
format.xml { render :xml => @videos }
end
end
# And the rest of CRUD ...
end
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30. Video sharing app
 Because this is a community site, lets not have admin
namespaced controllers just yet
class  We want users to be able submit videos in the context
VideosController < ApplicationController
of a category, and have that categorisation
# GET /videos, GET /videos.xml
automatically applied
def index
 What= Video.find(:all)
controllers do we need?
class CategoriesController < ApplicationControl
@videos
respond_to /categories, GET /categories.xml
# GET do |format|
def index
format.html # index.html.erb
@categories = Category.find(:all)
format.xml { render :xml => @videos }
end respond_to do |format|
end format.html # index.html.erb
format.xml { render :xml => @categories }
end
# And the rest of CRUD ...
end end
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# And the rest of CRUD ...

31. class CategoryVideosController < ApplicationC
Video sharing app
before_filter :load_category
# GET /categories/:category_id/videos
 Because this is a community site, lets not have admin
# GET /categories/:category_id/videos.xml
namespaced controllers just yet
def index
 We want users to be able submit videos in the context
class VideosController < ApplicationController
of a category, and=have that categorisation
@videos @category.videos.find(:all)
# GET /videos, GET /videos.xml
automatically applied do |format|
respond_to
def index format.html # index.html.erb
 What= Video.find(:all)
controllers do we need?
class CategoriesController < ApplicationControl
@videos
# GET /categories,{ GET /categories.xml
format.xml
respond_to do |format|
render :xml => @videos }
end
def index
format.html # index.html.erb
end
@categories = Category.find(:all)
format.xml { render :xml => @videos }
end respond_to do |format|
# And the rest of CRUD ...
end format.html # index.html.erb
format.xml { render :xml => @categories }
protected
end
# And the def load_category
rest of CRUD ...
end end @category = Category.find(params[:categor
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end
# And the rest of CRUD ...

32. map.resources :videos
class CategoryVideosController < ApplicationC
map.resourcesbefore_filter |category|
:categories do :load_category
Video sharing app
category.resources :videos, :controller => 'category_videos'
end
# GET /categories/:category_id/videos
 Because this is a community site, lets not have admin
# GET /categories/:category_id/videos.xml
namespaced controllers just yet
def index
 We want users to be able submit videos in the context
class VideosController < ApplicationController
of a category, and=have that categorisation
@videos @category.videos.find(:all)
# GET /videos, GET /videos.xml
automatically applied do |format|
respond_to
def index format.html # index.html.erb
 What= Video.find(:all)
controllers do we need?
class CategoriesController < ApplicationControl
@videos
# GET /categories,{ GET /categories.xml
format.xml
respond_to do |format|
render :xml => @videos }
end
def index
format.html # index.html.erb
end
@categories = Category.find(:all)
format.xml { render :xml => @videos }
end respond_to do |format|
# And the rest of CRUD ...
end format.html # index.html.erb
format.xml { render :xml => @categories }
protected
end
# And the def load_category
rest of CRUD ...
end end @category = Category.find(params[:categor
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end
# And the rest of CRUD ...

33. map.resources :videos
class CategoryVideosController < ApplicationC
map.resourcesbefore_filter |category|
:categories do :load_category
Video sharing app
category.resources :videos, :controller => 'category_videos'
end
# GET /categories/:category_id/videos
 Because this is a community site, lets not have admin
# GET /categories/:category_id/videos.xml
namespaced controllers just yet
def index
 We want users to be able submit videos in the context
class VideosController < ApplicationController
of a category, and=have that categorisation
@videos @category.videos.find(:all)
# GET /videos, GET /videos.xml
automatically applied do |format|
respond_to
def index format.html # index.html.erb
 What= Video.find(:all)
controllers do we need?
class CategoriesController < ApplicationControl
@videos
# GET /categories,{ GET /categories.xml
format.xml
respond_to do |format|
render :xml => @videos }
end
def index
format.html # index.html.erb
class Video < ActiveRecord::Base
attr_accessor end
@categories = Category.find(:all)
:category_for_new_record
# and a create hook to create the:xml => @videos }
format.xml { render categorisation
end end respond_to do |format|
# And the rest of CRUD ...
end format.html # index.html.erb
class Category < format.xml { render :xml => @categories }
ActiveRecord::Base
protected
has_many :videos, :through => :categorisations do
end
#def new(*args) load_category
And the defrest of CRUD ...
end @category = Category.find(params[:categor
end # pass proxy_owner through as :category_for_new_record
end ardes.com
end end
end # And the rest of CRUD ...

34. Video sharing app
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35. Video sharing app
 What views do we need?
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36. Video sharing app
 What views do we need?
 CRUD stuff
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37. Video sharing app
 What views do we need?
 CRUD stuff
 What about videos vs category_videos?
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38. Video sharing app
 What views do we need?
 CRUD stuff
 What about videos vs category_videos?
 Can use partials to factor out common stuff - but
there’s a cruical difference throughout
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39. Video sharing app
 What views do we need?
 CRUD stuff
 What about videos vs category_videos?
 Can use partials to factor out common stuff - but
there’s a cruical difference throughout
 In videos we want links and forms to new_video,
video
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40. Video sharing app
 What views do we need?
 CRUD stuff
 What about videos vs category_videos?
 Can use partials to factor out common stuff - but
there’s a cruical difference throughout
 In videos we want links and forms to new_video,
video
 In category_videos we want links to
new_category_video, and category_video.
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41. Video sharing app
 What views do we need?
 CRUD stuff
 What about videos vs category_videos?
 Can use partials to factor out common stuff - but
there’s a cruical difference throughout
 In videos we want links and forms to new_video,
video
 In category_videos we want links to
new_category_video, and category_video.
 We could use polymorphic_url, but we still need to
give it different arguments. (just the same as for the
controllers)
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42. Video sharing app
views/categories/index.html.erb
 What views do we need?
views/categories/show.html.erb
 CRUD stuff
views/categories/edit.html.erb
views/categories/new.html.erb
 What about videos vs category_videos?
 Can use partials to factor out common stuff - but
there’s a cruical difference throughout
 In videos we want links and forms to new_video,
video
 In category_videos we want links to
new_category_video, and category_video.
 We could use polymorphic_url, but we still need to
give it different arguments. (just the same as for the
controllers)
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43. Video sharing app
views/categories/index.html.erb
 What views do we need?
views/categories/show.html.erb
 CRUD stuff
views/categories/edit.html.erb
views/categories/new.html.erb
 What about videos vs category_videos?
 Can use partials to factor out common stuff - but
views/videos/index.html.erbthroughout
there’s a cruical difference
views/videos/show.html.erb forms to new_video,
 In videos we want links and
views/videos/edit.html.erb
video
views/videos/new.html.erb want links to
 In category_videos we
new_category_video, and category_video.
 We could use polymorphic_url, but we still need to
give it different arguments. (just the same as for the
controllers)
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44. Video sharing app
views/categories/index.html.erb
 What views do we need?
views/categories/show.html.erb
 CRUD stuff
views/categories/edit.html.erb
views/categories/new.html.erb
 What about videos vs category_videos?
 Can use partials to factor out common stuff - but
views/videos/index.html.erbthroughout
there’s a cruical difference
views/videos/show.html.erb forms to new_video,
 In videos we want links and
views/videos/edit.html.erb
video
views/videos/new.html.erb want links to
 In category_videos we
new_category_video, and category_video.
views/category_videos/index.html.erb still need to
 We could use polymorphic_url, but we
views/category_videos/show.html.erb
give it different arguments. (just the same as for the
controllers)
views/category_videos/edit.html.erb
views/category_videos/new.html.erb
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45. Video sharing app
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46. Video sharing app
 With vanilla Rails, it’s not too bad
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47. Video sharing app
 With vanilla Rails, it’s not too bad
 4 models, 3 controllers, 12 views, 3 lines of
routes
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48. Video sharing app
 With vanilla Rails, it’s not too bad
 4 models, 3 controllers, 12 views, 3 lines of
routes
 But, it doesn’t feel very DRY, does it?
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49. Video sharing app
 With vanilla Rails, it’s not too bad
 4 models, 3 controllers, 12 views, 3 lines of
routes
 But, it doesn’t feel very DRY, does it?
 Let’s see what happens if we want to add some
features
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50. Video sharing app: new feature
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51. Video sharing app: new feature
 We want to be able browse videos in the context
of the user that submitted them (similar to the
way we can browse by category)
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52. Video sharing app: new feature
 We want to be able browse videos in the context
of the user that submitted them (similar to the
way we can browse by category)
 (Lets assume we’ve added a UsersController
and views for browsing users themselves)
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53. map.resources :videos
map.resources :categories do |category|
category.resources :videos, :controller => 'category_videos'
end Video sharing app: new feature
map.resources :users do |user|
user.resources :videos, :controller => 'user_videos'
end  We want to be able browse videos in the context
of the user that submitted them (similar to the
way we can browse by category)
 (Lets assume we’ve added a UsersController
and views for browsing users themselves)
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54. map.resources :videos
map.resources :categories do |category|
category.resources :videos, :controller => 'category_videos'
end class UserVideosControllerapp: new feature
Video sharing < ApplicationController
before_filter :load_user
map.resources :users do |user|
user.resources :videos, :controller => 'user_videos'
# GET /users/:user_id/videos
end  We want /users/:user_id/videos.xml the context
# GET to be able browse videos in
of the user that submitted them (similar to the
def index
way we can browse by category)
@videos = @user.videos.find(:all)
 (Letsrespond_to do |format| UsersController
assume we’ve added a
and views for browsing users themselves)
format.html # index.html.erb
format.xml { render :xml => @videos }
end
end
# And the rest of CRUD ...
protected
def load_user
@user = User.find(params[:user_id])
end ardes.com
end

55. map.resources :videos
map.resources :categories do |category|
category.resources :videos, :controller => 'category_videos'
end class UserVideosControllerapp: new feature
Video sharing < ApplicationController
before_filter :load_user
map.resources :users do |user|
user.resources :videos, :controller => 'user_videos'
# GET /users/:user_id/videos
end  We want /users/:user_id/videos.xml the context
# GET to be able browse videos in
of the user that submitted them (similar to the
def index
way we can browse by category)
@videos = @user.videos.find(:all)
 (Letsrespond_to do |format| UsersController
assume we’ve added a
and views for browsing users themselves)
format.html # index.html.erb
format.xml { render :xml => @videos }
end
end
# And the rest of CRUD ...
views/user_videos/index.html.erb
protected
views/user_videos/show.html.erb
def load_user
views/user_videos/edit.html.erb
@user = User.find(params[:user_id])
views/user_videos/new.html.erb
end ardes.com
end

56. Video sharing app: new feature
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57. Video sharing app: new feature
 Another controller, and 4 more views, not bad
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58. Video sharing app: new feature
 Another controller, and 4 more views, not bad
 But our videos controllers all look very similar
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59. Video sharing app: new feature
 Another controller, and 4 more views, not bad
 But our videos controllers all look very similar
 How about a superclass abstraction?
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60. Video sharing app: new feature
 Another controller, and 4 more views, not bad
 But our videos controllers all look very similar
 How about a superclass abstraction?
 Problem: the action methods don’t look very easy
to abstract
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61. # VideosController (simplified)
def destroy
@video = Video.find(params[:id])
Video sharing app:
@video.destroy new feature
redirect_to videos_path
end
 Another controller, and 4 more views, not bad
 But our videos controllers all look very similar
 How about a superclass abstraction?
 Problem: the action methods don’t look very easy
to abstract
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62. # VideosController (simplified)
def destroy
@video = Video.find(params[:id])
Video sharing app:
@video.destroy new feature
redirect_to videos_path
end
 Another controller, and 4 more views, not bad
# CategoryVideosController
def destroy videos controllers all look very similar
But our
@video = @category.videos.find(params[:id])
 How about a superclass abstraction?
@video.destroy action methods don’t look very easy
 Problem: the
redirect_to category_videos_path(@category)
to abstract
end
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63. # VideosController (simplified)
def destroy
@video = Video.find(params[:id])
Video sharing app:
@video.destroy new feature
redirect_to videos_path
end
 Another controller, and 4 more views, not bad
# CategoryVideosController
def destroy videos controllers all look very similar
But our
@video = @category.videos.find(params[:id])
 How about a superclass abstraction?
@video.destroy action methods don’t look very easy
 Problem: the
redirect_to category_videos_path(@category)
to abstract
end
# UserVideosController
def destroy
@video = @user.videos.find(params[:id])
@video.destroy
redirect_to user_videos_path(@user)
end
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64. Video sharing app: new feature
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65. Video sharing app: new feature
 Users should be able to comment on videos,
users, and categories
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66. Video sharing app: new feature
 Users should be able to comment on videos,
users, and categories
 This looks like a job for :polymorphic
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67. Video sharing app: new feature
class User < ActiveRecord::Base
has_many :comments, :as => :commentable
 Users should be able to comment on
end
videos,
users, and categories
 Video < ActiveRecord::Base
class This looks like a job for :polymorphic
has_many :comments, :as => :commentable
end
class Category < ActiveRecord::Base
has_many :comments, :as => :commentable
end
class Comment
belongs_to :commentable, :polymorphic => true
end
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68. Video sharing app: new feature
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69. Video sharing app: new feature
 Now, one controller - or three controllers
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70. Video sharing app: new feature
 Now, one controller - or three controllers
 If we have one controller we face these problems
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71. Video sharing app: new feature
 Now, one controller - or three controllers
 If we have one controller we face these problems
- how to load up the comment?
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72. Video sharing app: new feature
 Now, one controller - or three controllers
 If we have one controller we face these problems
- how to load up the comment?
- how to redirect to the commentable?
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73. Video sharing app: new feature
 Now, one controller - or three controllers
 If we have one controller we face these problems
- how to load up the comment?
- how to redirect to the commentable?
 So lets try three controllers
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74. map.resources :videos do |video|
video.resources :comments, :controller => 'video_comments'
end
map.resources :categories do sharing app: new feature
Video |category|
category.resources :videos, :controller => 'category_videos'
category.resources :comments, :controller => 'category_comments'
end
 Now, one controller - or three controllers
map.resources :users do |user|
 If we have one controller we face these problems
user.resources :videos, :controller => 'user_videos'
- how to load up :controller =>
user.resources :comments, the comment? 'user_comments'
end
- how to redirect to the commentable?
 So lets try three controllers
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75. map.resources :videos do |video|
video.resources :comments, :controller => 'video_comments'
end
map.resources :categories do sharing app: new feature
Video |category|
category.resources :videos, :controller => 'category_videos'
category.resources :comments, :controller => 'category_comments'
end
class UserCommentsController < ApplicationController
 Now, one controller - or three controllers
before_filter :load_user
map.resources :users do |user|

def index If we have one controller we face these problems
user.resources :videos, :controller => 'user_videos'
@comments = @user.comments.find(:all)
- how to load up :controller =>
user.resources :comments, the comment? 'user_comments'
respond_to do |format|
format.html # index.html.erb
end
- how to redirect to the commentable?
format.xml { render :xml => @comments }
end
end
 So lets try three controllers
# And the rest of CRUD ...
protected
def load_user
@user = User.find(params[:user_id])
end
end
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76. map.resources :videos do |video|
video.resources :comments, :controller => 'video_comments'
end
map.resources :categories do sharing app: new feature
Video |category|
category.resources :videos, :controller => 'category_videos'
category.resources :comments, :controller => 'category_comments'
end
class UserCommentsController < ApplicationController
 Now, one controller - or three controllers
before_filter :load_user
map.resources :users do |user| ApplicationController

def index If we have one controller we face these problems
class CategoryCommentsController <
user.resources :videos, :controller => 'user_videos'
before_filter :load_category
@comments = @user.comments.find(:all)
- how to load up :controller =>
user.resources :comments, the comment? 'user_comments'
respond_to do |format|
def index
format.html # index.html.erb
end
- how |format|
end respond_to doto redirect to the commentable?
@comments = @category.comments.find(:all)
format.xml { render :xml => @comments }
end
 format.html{try three controllers}
So lets #render :xml => @comments
format.xml
index.html.erb
# And end rest of CRUD ...
the
end
protected
def # And the rest of CRUD ...
load_user
@user = User.find(params[:user_id])
protected
end
end def load_category
@category = Category.find(params[:category_id])
end
end
ardes.com

77. map.resources :videos do |video|
video.resources :comments, :controller => 'video_comments'
end
map.resources :categories do sharing app: new feature
Video |category|
category.resources :videos, :controller => 'category_videos'
category.resources :comments, :controller => 'category_comments'
end
class UserCommentsController < ApplicationController
 Now, one controller - or three controllers
before_filter :load_user
map.resources :users do |user| ApplicationController

def index If we have one controller we face these problems
class CategoryCommentsController <
user.resources :videos, :controller => 'user_videos'
before_filter :load_category
@comments = @user.comments.find(:all)
- VideoCommentsController < ApplicationController
user.resources :comments, the comment? 'user_comments'
class how to load up :controller =>
respond_to do |format|
def index
format.html # index.html.erb
end before_filter :load_video
- how |format|
end respond_to doto redirect to the commentable?
@comments = @category.comments.find(:all)
format.xml { render :xml => @comments }
def index
format.html # index.html.erb
end
 format.xml {try@video.comments.find(:all)
So lets =render :xmlcontrollers}
@comments three => @comments
the respond_to do |format|
# And end rest of CRUD ...
end format.html # index.html.erb
protected format.xml { render :xml => @comments }
end
def # And the rest of CRUD ...
load_user
end
@user = User.find(params[:user_id])
protected
end
end # And the rest of CRUD ...
def load_category
@category = Category.find(params[:category_id])
endprotected
end def load_video
@video = Video.find(params[:video_id])
end
end ardes.com

78. map.resources :videos do |video|
video.resources :comments, :controller => 'video_comments'
end
map.resources :categories do sharing app: new feature
Video |category| views/user_comments/index.html.erb
category.resources :videos, :controller => 'category_videos'
views/user_comments/show.html.erb
category.resources :comments, :controller => 'category_comments'
views/user_comments/edit.html.erb
end
class UserCommentsController < ApplicationController
views/user_comments/new.html.erb
 Now, one controller - or three controllers
before_filter :load_user
map.resources :users do |user| ApplicationController

def index If we have one controller we face these problems
class CategoryCommentsController <
user.resources :videos, :controller => 'user_videos'
before_filter :load_category
@comments = @user.comments.find(:all)
- VideoCommentsController < ApplicationController
user.resources :comments, the comment? 'user_comments'
class how to load up :controller =>
respond_to do |format|
def index
format.html # index.html.erb
end before_filter :load_video
- how |format|
end respond_to doto redirect to the commentable?
@comments = @category.comments.find(:all)
format.xml { render :xml => @comments }
def index
format.html # index.html.erb
end
 format.xml {try@video.comments.find(:all)
So lets =render :xmlcontrollers}
@comments three => @comments
the respond_to do |format|
# And end rest of CRUD ...
end format.html # index.html.erb
protected format.xml { render :xml => @comments }
end
def # And the rest of CRUD ...
load_user
end
@user = User.find(params[:user_id])
protected
end
end # And the rest of CRUD ...
def load_category
@category = Category.find(params[:category_id])
endprotected
end def load_video
@video = Video.find(params[:video_id])
end
end ardes.com

79. map.resources :videos do |video|
video.resources :comments, :controller => 'video_comments'
end
map.resources :categories do sharing app: new feature
Video |category| views/user_comments/index.html.erb
category.resources :videos, :controller => 'category_videos'
views/user_comments/show.html.erb
category.resources :comments, :controller => 'category_comments'
views/user_comments/edit.html.erb
end
class UserCommentsController < ApplicationController
views/user_comments/new.html.erb
 Now, one controller - or three controllers
before_filter :load_user
map.resources :users do |user| views/category_comments/index.html.erb

def index If we have one controller we face these problems
class CategoryCommentsController < ApplicationController
user.resources :videos, :controller => 'user_videos'
before_filter :load_category views/category_comments/show.html.erb
@comments = @user.comments.find(:all)
- VideoCommentsController < ApplicationController
user.resources :comments, the comment? 'user_comments'
class how to load up :controller =>
respond_to do |format|
def index
format.html # index.html.erb
views/category_comments/edit.html.erb
end before_filter :load_video views/category_comments/new.html.erb
- how |format|
end respond_to doto redirect to the commentable?
@comments = @category.comments.find(:all)
format.xml { render :xml => @comments }
def index
format.html # index.html.erb
end
 format.xml {try@video.comments.find(:all)
So lets =render :xmlcontrollers}
@comments three => @comments
the respond_to do |format|
# And end rest of CRUD ...
end format.html # index.html.erb
protected format.xml { render :xml => @comments }
end
def # And the rest of CRUD ...
load_user
end
@user = User.find(params[:user_id])
protected
end
end # And the rest of CRUD ...
def load_category
@category = Category.find(params[:category_id])
endprotected
end def load_video
@video = Video.find(params[:video_id])
end
end ardes.com

80. map.resources :videos do |video|
video.resources :comments, :controller => 'video_comments'
end
map.resources :categories do sharing app: new feature
Video |category| views/user_comments/index.html.erb
category.resources :videos, :controller => 'category_videos'
views/user_comments/show.html.erb
category.resources :comments, :controller => 'category_comments'
views/user_comments/edit.html.erb
end
class UserCommentsController < ApplicationController
views/user_comments/new.html.erb
 Now, one controller - or three controllers
before_filter :load_user
map.resources :users do |user| views/category_comments/index.html.erb

def index If we have one controller we face these problems
class CategoryCommentsController < ApplicationController
user.resources :videos, :controller => 'user_videos'
before_filter :load_category views/category_comments/show.html.erb
@comments = @user.comments.find(:all)
- VideoCommentsController < ApplicationController
user.resources :comments, the comment? 'user_comments'
class how to load up :controller =>
respond_to do |format|
def index
format.html # index.html.erb
views/category_comments/edit.html.erb
end before_filter :load_video views/category_comments/new.html.erb
- how |format|
end respond_to doto redirect to the commentable?
@comments = @category.comments.find(:all)
format.xml { render :xml => @comments }
def index
format.html # index.html.erb
end
 format.xml {try@video.comments.find(:all)
So lets =render :xmlcontrollers}
@comments three => @comments
views/video_comments/index.html.erb
the respond_to do |format|
# And end rest of CRUD ...
views/video_comments/show.html.erb
end format.html # index.html.erbviews/video_comments/edit.html.erb
protected format.xml { render :xml => views/video_comments/new.html.erb
@comments }
end
def # And the rest of CRUD ...
load_user
end
@user = User.find(params[:user_id])
protected
end
end # And the rest of CRUD ...
def load_category
@category = Category.find(params[:category_id])
endprotected
end def load_video
@video = Video.find(params[:video_id])
end
end ardes.com

81. Video sharing app: new feature
ardes.com

82. Video sharing app: new feature
 Damn, we forgot about commenting on videos
within the user and category contexts. (Let’s just
pretend that the customer, naively thinks that this
is something easy and obvious to do).
ardes.com

83. Video sharing app: new feature
 Damn, we forgot about commenting on videos
within the user and category contexts. (Let’s just
pretend that the customer, naively thinks that this
is something easy and obvious to do).
 Faced with the prospect of creating a bunch more
controllers and views, people start becoming
religious about Never nesting more than two
resources deep
ardes.com

84. Video sharing app: new feature
 Damn, we forgot about commenting on videos
within the user and category contexts. (Let’s just
pretend that the customer, naively thinks that this
is something easy and obvious to do).
 Faced with the prospect of creating a bunch more
controllers and views, people start becoming
religious about Never nesting more than two
resources deep
 But, the reasons we might want to do that haven’t
gone away, so we need to resort to some other
tricks, or just legislate against them
ardes.com

85. Video sharing app: rc’d
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86. Video sharing app: rc’d
 For the curious, this is what our app (without
comments - will come back to that later) would
look like when using resources_controller
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87. class UsersController < ApplicationController
Video sharing app: rc’d
resources_controller_for :users
end
 For the curious, this is what our app (without
comments - will come back to that later) would
look like when using resources_controller
class VideosController < ApplicationController
resources_controller_for :videos
end
class CategoriesController < ApplicationController
resources_controller_for :categories
end
ardes.com

88. Where is the logic?
class VideosController < ApplicationController
resources_controller_for :videos
end
ardes.com

89. Where is the logic?
class VideosController < ApplicationController
resources_controller_for :videos
end
# the controller resource logic is in routes.rb!
map.resources :videos
map.resources :categories do |category|
category.resources :videos
end
map.resources :users do |user|
user.resources :videos
end
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90. back to Rails w/o rc
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91. back to Rails w/o rc
 Seems like we have to do a lot of almost repeating
ourselves
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92. back to Rails w/o rc
 Seems like we have to do a lot of almost repeating
ourselves
- in actions
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93. back to Rails w/o rc
 Seems like we have to do a lot of almost repeating
ourselves
- in actions
- redirecting
ardes.com

94. back to Rails w/o rc
 Seems like we have to do a lot of almost repeating
ourselves
- in actions
- redirecting
- when loading enclosing resources
ardes.com

95. back to Rails w/o rc
 Seems like we have to do a lot of almost repeating
ourselves
- in actions
- redirecting
- when loading enclosing resources
- in views
ardes.com

96. back to Rails w/o rc
 Seems like we have to do a lot of almost repeating
ourselves
- in actions
- redirecting
- when loading enclosing resources
- in views
 It seems like the reverse of the way it should be (start
with fewer classes and views, branch when behaviour
requires it)
ardes.com

97. Plugins to the rescue!
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98. Plugins to the rescue!
 resources_controller
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99. Plugins to the rescue!
 resources_controller
 others
- make_resourceful
- resource_this
- resource_controller
- and more...
ardes.com

100. Plugins to the rescue!
 resources_controller
 others
- make_resourceful
- resource_this
- resource_controller
- and more...
 They all come with a set of actions that cover CRUD,
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101. Plugins to the rescue!
 resources_controller
 others
- make_resourceful
- resource_this
- resource_controller
- and more...
 They all come with a set of actions that cover CRUD,
 they all wrap up the pattern of loading enclosing
resources in some fashion
ardes.com

102. resources_controller: Goals
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103. resources_controller: Goals
NOT scaffolding - but it can be used for that
ardes.com

104. resources_controller: Goals
NOT scaffolding - but it can be used for that
stop repeating all of those actions
ardes.com

105. resources_controller: Goals
NOT scaffolding - but it can be used for that
stop repeating all of those actions
loading enclosing resources
ardes.com

106. resources_controller: Goals
NOT scaffolding - but it can be used for that
stop repeating all of those actions
loading enclosing resources
make referring to related resource URLs easy
ardes.com

107. resources_controller: Goals
NOT scaffolding - but it can be used for that
stop repeating all of those actions
loading enclosing resources
make referring to related resource URLs easy
principle of least surprise
ardes.com

108. resources_controller: Goals
NOT scaffolding - but it can be used for that
stop repeating all of those actions
loading enclosing resources
make referring to related resource URLs easy
principle of least surprise
Not a black box - RC internals should be able
to be used for solving other problems
ardes.com

109. Scaffolding vs abstraction
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110. Scaffolding vs abstraction
 Both are appropriate solutions for different problems
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111. Scaffolding vs abstraction
 Both are appropriate solutions for different problems
 In my view, many of the patterns that we’ve seen in
RESTful controllers warrant abstraction
ardes.com

112. Scaffolding vs abstraction
 Both are appropriate solutions for different problems
 In my view, many of the patterns that we’ve seen in
RESTful controllers warrant abstraction
 They enable some nice features in rc
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113. Scaffolding vs abstraction
 Both are appropriate solutions for different problems
 In my view, many of the patterns that we’ve seen in
RESTful controllers warrant abstraction
 They enable some nice features in rc
 They enable some nice solutions to REST
oriented problems
ardes.com

114. Scaffolding vs abstraction
 Both are appropriate solutions for different problems
 In my view, many of the patterns that we’ve seen in
RESTful controllers warrant abstraction
 They enable some nice features in rc
 They enable some nice solutions to REST
oriented problems
 Analogy: has_many and belongs_to, are not
implemented as sql scaffolds, but they could be.
Why is abstraction more appropriate here?
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115. Scaffolding vs abstraction
 Both are appropriate solutions for different problems
 In my view, many of the patterns that we’ve seen in
RESTful controllers warrant abstraction
 They enable some nice features in rc
 They enable some nice solutions to REST
oriented problems
 Analogy: has_many and belongs_to, are not
implemented as sql scaffolds, but they could be.
Why is abstraction more appropriate here?
 The problem is clearly defined
ardes.com

116. Scaffolding vs abstraction
 Both are appropriate solutions for different problems
 In my view, many of the patterns that we’ve seen in
RESTful controllers warrant abstraction
 They enable some nice features in rc
 They enable some nice solutions to REST
oriented problems
 Analogy: has_many and belongs_to, are not
implemented as sql scaffolds, but they could be.
Why is abstraction more appropriate here?
 The problem is clearly defined
 Abstraction enables cool stuff (like association
proxies)
ardes.com

117. resources_controller: abstraction
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118. resources_controller: abstraction
What’s the problem?
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119. resources_controller: abstraction
What’s the problem?
The model name is tightly coupled
with controller actions and views
ardes.com

120. resources_controller: abstraction
What’s the problem?
The model name is tightly coupled
with controller actions and views
so are the named routes
ardes.com

121. resources_controller: abstraction
What’s the problem?
The model name is tightly coupled
with controller actions and views
so are the named routes
and so is the resource service
ardes.com

122. class ForumsController < class UsersController <
ApplicationController ApplicationController
# GET /forums # GET /users
def index def index
@forums = Forum.find(:all) @users = User.find(:all)
end end
# GET /forums/1 # GET /users/1
def show def show
@forum = Forum.find(params[:id]) @user = User.find(params[:id])
end end
# DELETE /forums/1 # DELETE /users/1
def destroy def destroy
@forum = Forum.find(params[:id]) @user = User.find(params[:id])
@forum.destroy @user.destroy
redirect_to forums_path redirect_to users_path
end end

123. class ForumsController < class UsersController <
ApplicationController ApplicationController
# GET /forums # GET /users
def index def index
@forums = Forum.find(:all) @users = User.find(:all)
end end
# GET /forums/1 # GET /users/1
def show def show
@forum = Forum.find(params[:id]) @user = User.find(params[:id])
end end
# DELETE /forums/1 # DELETE /users/1
def destroy def destroy
@forum = Forum.find(params[:id]) @user = User.find(params[:id])
@forum.destroy @user.destroy
redirect_to forums_path redirect_to users_path
end end

124. class ForumsController < class UsersController <
ApplicationController ApplicationController
# GET /forums # GET /users
def index def index
@forums = Forum.find(:all) @users = User.find(:all)
end end
# GET /forums/1 # GET /users/1
def show def show
@forum = Forum.find(params[:id]) @user = User.find(params[:id])
end end
# DELETE /forums/1 # DELETE /users/1
def destroy def destroy
@forum = Forum.find(params[:id]) @user = User.find(params[:id])
@forum.destroy @user.destroy
redirect_to forums_path redirect_to users_path
end end

125. class ForumsController < class UsersController <
ApplicationController ApplicationController
# GET /forums # GET /users
def index def index
@forums = Forum.find(:all) @users = User.find(:all)
end end
# GET /forums/1 # GET /users/1
def show def show
@forum = Forum.find(params[:id]) @user = User.find(params[:id])
end end
# DELETE /forums/1 # DELETE /users/1
def destroy def destroy
@forum = Forum.find(params[:id]) @user = User.find(params[:id])
@forum.destroy @user.destroy
redirect_to forums_path redirect_to users_path
end end

126. de-couple the name: resource
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127. de-couple the name: resource
def destroy
self.resource = find_resource
resource.destroy
#
end
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128. de-couple the name: resource
def destroy
self.resource = find_resource
resource.destroy
#
end
this will, e.g. set @forum to Forums.find(params[:id])
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129. de-couple the name: resource
def destroy
self.resource = find_resource
resource.destroy
#
end
this will, e.g. set @forum to Forums.find(params[:id])
we can refer to whatever the current resource is with resource
ardes.com

130. de-couple named routes:
resource(s)_path
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131. de-couple named routes:
resource(s)_path
def destroy
self.resource = find_resource
resource.destroy
redirect_to resources_path
end
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132. de-couple named routes:
resource(s)_path
def destroy
self.resource = find_resource
resource.destroy
redirect_to resources_path
end
all named routes are supported, e.g.
formatted_resource_tags_url(‘js’)
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133. de-couple named routes:
resource(s)_path
def destroy
self.resource = find_resource
resource.destroy
redirect_to resources_path
end
all named routes are supported, e.g.
formatted_resource_tags_url(‘js’)
think of this as named routes
relativised to the current resource
ardes.com

134. de-couple class or association:
resource_service
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135. de-couple class or association:
resource_service
def find_resource(id = params[:id])
resource_service.find id
end
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136. de-couple class or association:
resource_service
def find_resource(id = params[:id])
resource_service.find id
end
resource_service is an ActiveRecord class,
or an association proxy
ardes.com

137. de-couple class or association:
resource_service
def find_resource(id = params[:id])
resource_service.find id
end
resource_service is an ActiveRecord class,
or an association proxy
(it’s actually a bit more than that - but think of it that way)
ardes.com

138. resource_service
def find_resources
resource_service.find :all
end
def find_resource(id = params[:id])
resource_service.find id
end
def new_resource(attributes = params[resource_name])
resource_service.new attributes
end
ardes.com

139. resource_service
def find_resources
resource_service.find :all, :order => params[:order]
end
def find_resource(id = params[:id])
resource_service.find id
end
def new_resource(attributes = params[resource_name])
resource_service.new attributes
end
ardes.com

140. load enclosing resources
it’s easy, but repetitive.
you need to do it, for url/model integrity
ardes.com

141. load enclosing resources
it’s easy, but repetitive.
you need to do it, for url/model integrity
the information is already expressed
in routes.rb (most of the time)
ardes.com

142. load enclosing resources
it’s easy, but repetitive.
you need to do it, for url/model integrity
the information is already expressed
in routes.rb (most of the time)
resources_controller thinks that one controller
for multiple routes is a fine idea
ardes.com

143. ardes.com

144. /users/2/forums/3
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145. @user = User.find(2)
/users/2/forums/3
@forum = @user.forums.find(3)
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146. @user = User.find(2)
/users/2/forums/3
@forum = @user.forums.find(3)
/users/2/forums/3/tags
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147. @user = User.find(2)
/users/2/forums/3
@forum = @user.forums.find(3)
/users/2/forums/3/tags
@user = User.find(2)
@forum = @user.forums.find(3)
@tags = @forum.tags.find(:all)
ardes.com

148. @user = User.find(2)
/users/2/forums/3
@forum = @user.forums.find(3)
/users/2/forums/3/tags
@user = User.find(2)
@forum = @user.forums.find(3)
@tags = @forum.tags.find(:all)
/users/2/image/comments
ardes.com

149. @user = User.find(2)
/users/2/forums/3
@forum = @user.forums.find(3)
/users/2/forums/3/tags
@user = User.find(2)
@forum = @user.forums.find(3)
@tags = @forum.tags.find(:all)
/users/2/image/comments
@user = User.find(2)
@image = @user.image
@comments = @image.comments.find(:all)
ardes.com

150. resource specification
ardes.com

151. resource specification
routing does the work of extracting
logical reosurces from the url
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152. resource specification
routing does the work of extracting
logical reosurces from the url
and then THROWS IT AWAY
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153. resource specification
routing does the work of extracting
logical reosurces from the url
and then THROWS IT AWAY
in the mean time: RC re-recognizes the route,
and parses it according to the specification
ardes.com

154. principle of least surprise
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155. principle of least surprise
class UserForumsController < ApplicationController
resources_controller_for :forums, :in => :user
def mark_as_boring
@forum = @user.forums.find(params[:id])
@forum.boringed_by!(@user)
redirect_to user_forums_path(@user)
end
end
ardes.com

156. principle of least surprise
class UserForumsController < ApplicationController
resources_controller_for :forums, :in => :user
def mark_as_boring
@forum = @user.forums.find(params[:id])
@forum.boringed_by!(@user)
redirect_to user_forums_path(@user)
end
end
<%= @forum.title %>
<%= @user.name %>
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157. principle of least surprise
class UserForumsController < ApplicationController
resources_controller_for :forums, :in => :user
def mark_as_boring
@forum = @user.forums.find(params[:id])
@forum.boringed_by!(@user)
redirect_to user_forums_path(@user)
end
end
<%= @forum.title %>
<%= @user.name %>
<%= link_to @forum.name, polymorphic_url [@user, @forum] %>
ardes.com

158. Back to our video app
 What if we want to add comments on videos, users,
categories - and also have them in user_videos and
category_videos?
ardes.com

159. class UsersController < ApplicationController
resources_controller_for :users
end
Back to our video app
class VideosController < ApplicationController
 What if we want to add comments on videos, users,
resources_controller_for :videos
end categories - and also have them in user_videos and
category_videos?
class CategoriesController < ApplicationController
resources_controller_for :categories
end
class CommentsController < ApplicationController
resources_controller_for :comments
nested_in :commentable, :polymorphic => true
end
ardes.com

160. map.resources :videos, :has_many => :comments
map.resources :categories ApplicationController
class UsersController < do |category|
category.resources :videos,:users
resources_controller_for :has_many => :comments
end
end
map.resources our video<app
Back to :users do |user|
class VideosController ApplicationController
user.resources want to add :has_many on videos, users,
 What if we :videos, comments => :comments
resources_controller_for :videos
endend categories - and also have them in user_videos and
category_videos?
class CategoriesController < ApplicationController
resources_controller_for :categories
end
class CommentsController < ApplicationController
resources_controller_for :comments
nested_in :commentable, :polymorphic => true
end
ardes.com

161. map.resources :videos, :has_many => :comments
map.resources :categories ApplicationController
class UsersController < do |category|
category.resources :videos,:users
resources_controller_for :has_many => :comments
end
end
map.resources our video<app
Back to :users do |user|
class VideosController ApplicationController
user.resources want to add :has_many on videos, users,
 What if we :videos, comments => :comments
resources_controller_for :videos
endend categories - and also have them in user_videos and
category_videos?
With RC
class CategoriesController < ApplicationController
resources_controller_for :categories
You start with fewer controllers and views
end
You make more when you have too much behaviour crammed into them
class CommentsController < ApplicationController
resources_controller_for :comments
nested_in :commentable, :polymorphic => true
end
ardes.com

162. Common patterns, rc’d
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163. Common patterns, rc’d
 account pattern
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164. Common patterns, rc’d
 account pattern
 ordering a collection
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165. Common patterns, rc’d
 account pattern
 ordering a collection
 join models
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166. account pattern
 Account pattern
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167. account pattern
map.resource :account do |account|
 Account pattern account.resources :images
account.resources :posts
end
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168. account pattern
map.resource :account do |account|
 Account pattern account.resources :images
account.resources :posts
end
class AccountController < ApplicationController
resources_controller_for :account, :class => User, :singleton => true do
current_user
end
end
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169. account pattern
map.resource :account do |account|
 Account pattern account.resources :images
account.resources :posts
end
class AccountController < ApplicationController
resources_controller_for :account, :class => User, :singleton => true do
current_user
end
end
# You don't need to make an AccountImages, or AccountPosts controller!
class ApplicationController < ActionController::Base
map_enclosing_resource :account, :class => User, :singleton => true do
current_user
end
# or you can put the above in each controller which has :account in its
# enclosing resources, or in a mixin
end ardes.com

170. ordering a collection
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171. ordering a collection
map.resources :users do |user|
users.resources :things, :collection => {:order => :put}
end
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172. ordering a collection
map.resources :users do |user|
users.resources :things, :collection => {:order => :put}
end
class Thing < ActiveRecord::Base
acts_as_list
def self.order_by_ids(ids)
transaction do
ids.each_index do |i|
Thing.update_attribute! :position => i+1
end
end
end
end ardes.com

173. ordering a collection
map.resources :users do |user|
users.resources :things, :collection => {:order => :put}
end
def order
resource_service.order_by_ids[quot;#{resource_name}_orderquot;]
end
class Thing < ActiveRecord::Base
acts_as_list
def self.order_by_ids(ids)
transaction do
ids.each_index do |i|
Thing.update_attribute! :position => i+1
end
end
end
end ardes.com

174. Join model controllers
class ModeratorshipsController < Applica...
resources_controller_for :moderatorships,
:actions => nil
def create # ...
def destroy # ...
end

175. class ModeratorshipsController < Applica...
resources_controller_for :moderatorships,
:actions => nil
def create
self.resource = new_resource
if resource.save
flash[:notice] = “#{resource_name} created”
else
flash[:error] = ‘oops’
end
redirect_to enclosing_resource_path
end
def destroy # ...

176. class ModeratorshipsController < Applica...
resources_controller_for :moderatorships,
:actions => nil
def create # ...
end
def destroy
self.resource = find_resource
resource.destroy
flash[:notice] = “#{resource_name} destroyed”
redirect_to enclosing_resource_path
end

177. test controller plugins
garlic do
repo 'rails', :url => 'git://github.com/rails/rails'
repo 'rspec', :url => 'git://github.com/ianwhite/rspec'
repo 'rspec-rails', :url => 'git://github.com/ianwhite/rspec-rails'
repo 'resources_controller', :path => '.'
target 'edge', :branch => 'master'
target '2.0-stable', :branch => 'origin/2-0-stable'
target '2.1-stable', :branch => 'origin/2-1-stable'
target '2.1.0', :tag => 'v2.1.0'
all_targets do
prepare do
plugin 'resources_controller', :clone => true
plugin 'rspec'
plugin('rspec-rails') { sh quot;script/generate rspec -fquot; }
end
run do
cd ‘vendor/plugins/resources_controller’ do
sh quot;rake spec:rcov:verifyquot;
end ardes.com
end
end

179. RC summary
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180. RC summary
 makes RESTful controllers and views easier
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181. RC summary
 makes RESTful controllers and views easier
- Start with fewer controllers/views - make more when
required
ardes.com

182. RC summary
 makes RESTful controllers and views easier
- Start with fewer controllers/views - make more when
required
 sightings
ardes.com

183. RC summary
 makes RESTful controllers and views easier
- Start with fewer controllers/views - make more when
required
 sightings
- rc just got forked by revolutionhealth on github
ardes.com

184. RC summary
 makes RESTful controllers and views easier
- Start with fewer controllers/views - make more when
required
 sightings
- rc just got forked by revolutionhealth on github
- Lots of production apps
ardes.com

185. RC summary
 makes RESTful controllers and views easier
- Start with fewer controllers/views - make more when
required
 sightings
- rc just got forked by revolutionhealth on github
- Lots of production apps
 well speced
ardes.com

186. What next?
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187. What next?
 abstract idea of resource, passed by routing to
controller on the request (you were invoked with this
resource)
ardes.com

188. What next?
 abstract idea of resource, passed by routing to
controller on the request (you were invoked with this
resource)
 refactoring?
ardes.com

189. What next?
 abstract idea of resource, passed by routing to
controller on the request (you were invoked with this
resource)
 refactoring?
 core-list talk about loading resources in controllers
ardes.com

190. Writing resources_controller
Discovering REST patterns in Rails
Ian White
github.com/ianwhite
blog.ardes.com/ian
Argument from Design ardes.com
Sheffield, UK