Getting started with Rails (4), Season 2
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The document provides instructions for adding a third model called Tag to a Rails blog project. It describes generating the Tag model and migration file, setting up relationships between the Post and Tag models using belongs_to and has_many, enabling nested attributes to save tags through posts, and building a multi-model form to submit posts and tags together.
![#accepts_nested
_attributes_for
• tags_attributes=(attributes)
• :allow_destroy => true
“_destroy” key, evaluated to true
• :reject_if => proc { |attributes|
attributes[‘name’].blank? }
• :reject_if => proc { |attrs| attrs.all? { |k,v|
v.blank?} }
ROR Lab.](https://image.slidesharecdn.com/season2-04-shared-120817184318-phpapp01/85/Getting-started-with-Rails-4-Season-2-6-320.jpg)
Getting started with Rails (4), Season 2
- 1. ROR Lab. Season 2 - The 4th Round - Getting Started with Rails (4) August 11, 2012 Hyoseong Choi ROR Lab.
- 2. A Blog Project Post ny on a m separate form nested form e to form_for to ne m an o y Comment Tag form_for fields_for ROR Lab.
- 3. Generating the 3rd Model : Tag $ rails generate model tag name:string post:references Migration file Model Class : db/migrate/xxxx_create_tag.rb : app/models/tag.rb Tag tags $ rake db:migrate belongs_to :post post_id :integer post:references ROR Lab.
- 4. Nested Attributes • save the child object through the parent object • Off, by default • switch “On”, by calling #accepts_nested_attributes_for • an attribute writer automatically defined on the parent model • :autosave option automatically enabled http://api.rubyonrails.org/classes/ActiveRecord/NestedAttributes/ClassMethods.html ROR Lab.
- 5. Building a Multi- Model Form ✔ class Post < ActiveRecord::Base attr_accessible :content, :name, :title, :tags_attributes validates :name, :presence => true validates :title, :presence => true, :length => { :minimum => 5 } has_many :comments, :dependent => :destroy has_many :tags ✔ accepts_nested_attributes_for :tags, :allow_destroy => :true, :reject_if => proc { |attrs| attrs.all? { |k, v| v.blank? } } end ✔ multi-model form or nested form or form in form ROR Lab.
- 6. #accepts_nested _attributes_for • tags_attributes=(attributes) • :allow_destroy => true “_destroy” key, evaluated to true • :reject_if => proc { |attributes| attributes[‘name’].blank? } • :reject_if => proc { |attrs| attrs.all? { |k,v| v.blank?} } ROR Lab.
- 7. build vs new • new ➞ for Class ex) post = Post.new • build ➞ for association proxy ex) comment = post.comments.build ✓ automatic setting its foreign key for the new child object with patient object id ROR Lab.
- 8. <% @post.tags.build %> <%= form_for(@post) do |post_form| %> <div class="field"> <%= post_form.label :name %><br /> <%= post_form.text_field :name %> </div> <div class="field"> <%= post_form.label :title %><br /> <%= post_form.text_field :title %> </div> <div class="field"> <%= post_form.label :content %><br /> <%= post_form.text_area :content %> </div> <h2>Tags</h2> <%= post_form.fields_for :tags do |tag_form| %> <div class="field"> <%= tag_form.label :name, 'Tag:' %> <%= tag_form.text_field :name %> </div> <% unless tag_form.object.nil? || tag_form.object.new_record? %> <div class="field"> <%= tag_form.label :_destroy, 'Remove:' %> <%= tag_form.check_box :_destroy %> </div> <% end %> <% end %> <div class="actions"> <%= post_form.submit %> </div> <% end %> ✔ app/views/posts/_form.html.erb ROR Lab.
- 9. <% @post.tags.build %> <%= form_for(@post) do |post_form| %> <div class="field"> <%= post_form.label :name %><br /> <%= post_form.text_field :name %> </div> <div class="field"> <%= post_form.label :title %><br /> <%= post_form.text_field :title %> </div> <div class="field"> <%= post_form.label :content %><br /> accets_nested_attributes_for :tags <%= post_form.text_area :content %> </div> <h2>Tags</h2> <%= post_form.fields_for :tags do |tag_form| %> <div class="field"> <%= tag_form.label :name, 'Tag:' %> <%= tag_form.text_field :name %> </div> <% unless tag_form.object.nil? || tag_form.object.new_record? %> <div class="field"> <%= tag_form.label :_destroy, 'Remove:' %> <%= tag_form.check_box :_destroy %> </div> <% end %> <% end %> <div class="actions"> <%= post_form.submit %> </div> <% end %> ✔ app/views/posts/_form.html.erb ROR Lab.
- 10. <% @post.tags.build %> <%= form_for(@post) do |post_form| %> <div class="field"> <%= post_form.label :name %><br /> <%= post_form.text_field :name %> </div> <div class="field"> <%= post_form.label :title %><br /> <%= post_form.text_field :title %> </div> <div class="field"> <%= post_form.label :content %><br /> accets_nested_attributes_for :tags <%= post_form.text_area :content %> </div> tags_attributes <h2>Tags</h2> <%= post_form.fields_for :tags do |tag_form| %> <div class="field"> <%= tag_form.label :name, 'Tag:' %> <%= tag_form.text_field :name %> </div> <% unless tag_form.object.nil? || tag_form.object.new_record? %> <div class="field"> <%= tag_form.label :_destroy, 'Remove:' %> <%= tag_form.check_box :_destroy %> </div> <% end %> <% end %> <div class="actions"> <%= post_form.submit %> </div> <% end %> ✔ app/views/posts/_form.html.erb ROR Lab.
- 11. <% @post.tags.build %> <%= form_for(@post) do |post_form| %> <% if @post.errors.any? %> <div id="errorExplanation"> <h2><%= pluralize(@post.errors.count, "error") %> prohibited this post from being saved:</h2> <ul> <% @post.errors.full_messages.each do |msg| %> <li><%= msg %></li> <% end %> </ul> <%= form.fields_for :tags do |tag_form| %> </div> <div class="field"> <% end %> <%= tag_form.label :name, 'Tag:' %> <%= tag_form.text_field :name %> <div class="field"> </div> <%= post_form.label :name %><br /> <% unless tag_form.object.nil? || tag_form.object.new_record? %> <%= post_form.text_field :name %> <div class="field"> </div> <%= tag_form.label :_destroy, 'Remove:' %> <div class="field"> <%= tag_form.check_box :_destroy %> <%= post_form.label :title %><br /> </div> <%= post_form.text_field :title %> <% end %> </div> <% end %> <div class="field"> ✔ app/views/tags/_form.html.erb <%= post_form.label :content %><br /> <%= post_form.text_area :content %> </div> <h2>Tags</h2> <%= render :partial => 'tags/form', :locals => {:form => post_form} %> <div class="actions"> <%= post_form.submit %> </div> <% end %> ✔ app/views/posts/_form.html.erb ROR Lab.
- 12. <p id="notice"><%= notice %></p> <p> <b>Name:</b> <%= @post.name %> </p> <p> module PostsHelper <b>Title:</b> def join_tags(post) <%= @post.title %> post.tags.map { |t| t.name }.join(", ") </p> end end <p> <b>Content:</b> ✔ app/helpers/posts_helper.rb <%= @post.content %> </p> <p> <p> <b>Tags:</b> <b>Tags:</b> <%= @post.tags.map { |t| t.name }.join(", ") %> <%= join_tags(@post) %> </p> </p> <h2>Comments</h2> <%= render @post.comments %> <h2>Add a comment:</h2> <%= render "comments/form" %> <%= link_to 'Edit Post', edit_post_path(@post) %> | <%= link_to 'Back to Posts', posts_path %> | ✔ app/views/posts/show.html.erb ROR Lab.
- 13. <p id="notice"><%= notice %></p> <p> <b>Name:</b> <%= @post.name %> </p> <p> module PostsHelper <b>Title:</b> def join_tags(post) <%= @post.title %> post.tags.map { |t| t.name }.join(", ") </p> end end <p> <b>Content:</b> ✔ app/helpers/posts_helper.rb <%= @post.content %> </p> <p> <p> <b>Tags:</b> <b>Tags:</b> <%= join_tags(@post) %> <%= join_tags(@post) %> </p> </p> <h2>Comments</h2> <%= render @post.comments %> <h2>Add a comment:</h2> <%= render "comments/form" %> <%= link_to 'Edit Post', edit_post_path(@post) %> | <%= link_to 'Back to Posts', posts_path %> | ✔ app/views/posts/show.html.erb ROR Lab.
- 14. Live Demo Creating a project ~ 3rd model, Tag ROR Lab.
- 15. 감사합니다.