接着上面的母子表单

Creating a new Rails project

$ mkdir family

# create rvm gemset
$ echo "rvm use --create ruby-1.9.2@family"> family/.rvmrc

$ cd family

# install rails
$ gem install rails

# create new rails project
$ rails new.# version control
$ git init
$ git add .
$ git commit -am "new rails project"

Create two models (Parent & Child)

# Parent model
$ rails generate scaffold Parent name:string
$ git add .
$ git commit -am "rails generate scaffold Parent name:string"# Child model
$ rails generate scaffold Child name:string parent_id:integer
$ git add .
$ git commit -am "rails generate scaffold Child name:string parent_id:integer"# Create db (defaults to SQLite3)
$ rake db:migrate

# version control
$ git add db/schema.rb
$ git commit db/schema.rb -m "created database schema"

Review un-nested routes

$ rake routes
   children GET    /children(.:format)          children#index
            POST   /children(.:format)          children#create
  new_child GET    /children/new(.:format)      children#new
 edit_child GET    /children/:id/edit(.:format) children#edit
      child GET    /children/:id(.:format)      children#show
            PUT    /children/:id(.:format)      children#update
            DELETE /children/:id(.:format)      children#destroy
    parents GET    /parents(.:format)           parents#index
            POST   /parents(.:format)           parents#create
 new_parent GET    /parents/new(.:format)       parents#new
edit_parent GET    /parents/:id/edit(.:format)  parents#edit
     parent GET    /parents/:id(.:format)       parents#show
            PUT    /parents/:id(.:format)       parents#update
            DELETE /parents/:id(.:format)       parents#destroy

Adding model relationships

# file: app/models/parent.rbclassParent<ActiveRecord::Base
  attr_accessible :name
  has_many :children
end# file: app/models/child.rbclassChild<ActiveRecord::Base
  attr_accessible :name,:parent_id
  belongs_to :parent
end# version control
$ git commit app/models -m "added relationships to models"

Nesting the routes

# file: config/routes.rb-  resources :children
-  resources :parents
+  resources :parents do+    resources :children
+end# version control
$ git commit -m config/routes.rb "nested resources in routes file"

Reviewing changes to routes

$ rake routes
  parent_children GET    /parents/:parent_id/children(.:format)          children#index
                  POST   /parents/:parent_id/children(.:format)          children#create
 new_parent_child GET    /parents/:parent_id/children/new(.:format)      children#new
edit_parent_child GET    /parents/:parent_id/children/:id/edit(.:format) children#edit
     parent_child GET    /parents/:parent_id/children/:id(.:format)      children#show
                  PUT    /parents/:parent_id/children/:id(.:format)      children#update
                  DELETE /parents/:parent_id/children/:id(.:format)      children#destroy
          parents GET    /parents(.:format)                              parents#index
                  POST   /parents(.:format)                              parents#create
       new_parent GET    /parents/new(.:format)                          parents#new
      edit_parent GET    /parents/:id/edit(.:format)                     parents#edit
           parent GET    /parents/:id(.:format)                          parents#show
                  PUT    /parents/:id(.:format)                          parents#update
                  DELETE /parents/:id(.:format)                          parents#destroy

Adding test data via Rails console

$ rails c

> dad =Parent.new(:name =>'Paul')=>#<Parent id: nil, name: "Paul", created_at: nil, updated_at: nil> > dad.save
   (0.1ms)begin transaction
  SQL (20.0ms)  INSERT INTO "parents"("created_at","name","updated_at") VALUES (?,?,?)[["created_at",Fri,06Apr201216:13:17 UTC +00:00],["name","Paul"],["updated_at",Fri,06Apr201216:13:17 UTC +00:00]](2.4ms)  commit transaction
 =>true> son = dad.children.new(:name =>'Eric')=>#<Child id: nil, name: "Eric", parent_id: 1, created_at: nil, updated_at: nil> > daughter = dad.children.new(:name =>'Mara')=>#<Child id: nil, name: "Mara", parent_id: 1, created_at: nil, updated_at: nil> >exit

Adding a private controller method to load the Parent object for each method

# file: app/controllers/children_controller.rb@@-1,4+1,7@@classChildrenController<ApplicationController++  before_filter :load_parent
+# GET /children# GET /children.jsondef index
@@-80,4+83,11@@classChildrenController<ApplicationController
       format.json { head :no_content }endend++private++def load_parent
+@parent=Parent.find(params[:parent_id])+end+end

At this point, each controller and view for the Child class model needs to be adjusted (links, redirection, form, etc)

Method: children#index

# file: app/controllers/children_controller.rbdef index
-@children=Child.all
+@children=@parent.children.all

# file: app/views/children/index.html.erb-<td><%= link_to 'Show', child %></td>-<td><%= link_to 'Edit', edit_child_path(child)%></td>-<td><%= link_to 'Destroy', child, confirm:'Are you sure?', method::delete%></td>+<td><%= link_to 'Show', parent_child_path(@parent, child)%></td>+<td><%= link_to 'Edit', edit_parent_child_path(@parent, child)%></td>+<td><%= link_to 'Destroy',[@parent, child], confirm:'Are you sure?', method::delete%></td>-<%= link_to 'New Child', new_child_path %>+<%= link_to 'New Child', new_parent_child_path(@parent)%>

Method: children#new

# file: app/controllers/children_controller.rbdefnew-@child=Child.new+@child=@parent.children.new

# file: app/views/children/_form.html.erb-<%= form_for(@child)do|f|%>+<%= form_for([@parent,@child])do|f|%>

# file: app/views/children/new.html.erb-<%= link_to 'Back', children_path %>+<%= link_to 'Back', parent_children_path(@parent)%>

Method: children#create

# file: app/controllers/children_controller.rbdef create
-@child=Child.new(params[:child])+@child=@parent.children.new(params[:child])
 
     respond_to do|format|[e-mail]
-        format.html { redirect_to @child, notice:'Child was successfully created.'}+        format.html { redirect_to [@parent,@child], notice:'Child was successfully created.'}

Method: children#show

# file: app/controllers/children_controller.rbdef show
-@child=Child.find(params[:id])+@child=@parent.children.find(params[:id])

# file: app/views/children/show.html.erb-<%= link_to 'Edit', edit_child_path(@child)%>|-<%= link_to 'Back', children_path %>+<%= link_to 'Edit', edit_parent_child_path(@parent,@child)%>|+<%= link_to 'Back', parent_children_path(@parent)%>

Method: children#edit

# file: app/controllers/children_controller.rbdef edit
-@child=Child.find(params[:id])+@child=@parent.children.find(params[:id])

# file: app/views/children/edit.html.erb-<%= link_to 'Show',@child%>|-<%= link_to 'Back', children_path %>+<%= link_to 'Show', parent_child_path(@parent,@child)%>|+<%= link_to 'Back', parent_children_path(@parent)%>

Method: children#update

# file: app/controllers/children_controller.rbdef update
-@child=Child.find(params[:id])+@child=@parent.children.find(params[:id])
 
     respond_to do|format|[e-mail]_attributes(params[:child])-        format.html { redirect_to @child, notice:'Child was successfully updated.'}+        format.html { redirect_to [@parent,@child], notice:'Child was successfully updated.'}

Method: children#destroy

# file: app/controllers/children_controller.rbdef destroy
-@child=Child.find(params[:id])+@child=@parent.children.find(params[:id])@child.destroy
 
     respond_to do|format|-      format.html { redirect_to children_url }+      format.html { redirect_to parent_children_path(@parent)}

At this point, the default scaffolding's links and redirection have been updated to work with the nested routes.