问题
My model structure looks like this:
Board has_many Topics. Topic has_many Posts.
app/models/board.rb
class Board < ActiveRecord::Base
has_many :topics
end
app/models/topic.rb
class Topic < ActiveRecord::Base
belongs_to :user
belongs_to :board
has_many :posts
accepts_nested_attributes_for :posts
validates :title, presence: true, length: { maximum: 255 }
validates :user_id, presence: true
validates :board_id, presence: true
...
end
app/models/post.rb
class Post < ActiveRecord::Base
belongs_to :user
belongs_to :topic
validates :user_id, presence: true
validates :topic_id, presence: true
validates :content, length: { minimum: 8 }
end
Here is my view for creating a new Topic. the fields_for section is used to create the :content on the new Post
app/views/topics/new.html.erb
<div>
<%= form_for [@board, @topic] do |f| %>
<%= render 'shared/error_messages', object: @topic %>
<%= f.label :title %>
<%= f.text_field :title %>
<%= f.fields_for @post do |p| %>
<%= p.label :content %>
<%= p.text_area :content %>
<% end %>
<%= f.submit "Post new topic", class: "button submit" %>
<% end %>
</div>
When creating a new Topic, I want a new post with the :content from the form to also be created. Since the Post is dependent on having a Topic in order to be valid, they need to be created or rejected in tandem (if the :content or :title is invalid). I was told that accepts_nested_attributes_for would work correctly but when my code executes it only creates the Topic, not the Post.
app/controllers/topics_controller.rb
def new
@board = Board.find(params[:board_id])
@topic = @board.topics.build
@post = @topic.posts.build
end
def create
@board = Board.find(params[:board_id])
@topic = @board.topics.build(topic_params.merge({user_id: current_user.id}))
if @topic.save
flash[:success] = "Topic created"
redirect_to @topic
else
render 'new'
end
end
private
def topic_params
params.require(:topic).permit(:title, posts_attributes: [:content])
end
For the record, here is my Posts controller and routes, if it helps.
app/controllers/posts_controller.rb
def create
@topic = Topic.find(params[:topic_id])
@post = @topic.posts.build(post_params.merge({user_id: current_user.id}))
if @post.save
flash[:success] = "Post Created"
redirect_to topic_path(@topic)
else
render 'new'
end
end
private
def post_params
params.require(:post).permit(:content)
end
rake routes for Boards, Topics and Posts
topic_posts GET /topics/:topic_id/posts(.:format) posts#index
POST /topics/:topic_id/posts(.:format) posts#create
new_topic_post GET /topics/:topic_id/posts/new(.:format) posts#new
edit_post GET /posts/:id/edit(.:format) posts#edit
post GET /posts/:id(.:format) posts#show
PATCH /posts/:id(.:format) posts#update
PUT /posts/:id(.:format) posts#update
DELETE /posts/:id(.:format) posts#destroy
board_topics GET /boards/:board_id/topics(.:format) topics#index
POST /boards/:board_id/topics(.:format) topics#create
new_board_topic GET /boards/:board_id/topics/new(.:format) topics#new
edit_topic GET /topics/:id/edit(.:format) topics#edit
topic GET /topics/:id(.:format) topics#show
PATCH /topics/:id(.:format) topics#update
PUT /topics/:id(.:format) topics#update
DELETE /topics/:id(.:format) topics#destroy
boards GET /boards(.:format) boards#index
POST /boards(.:format) boards#create
new_board GET /boards/new(.:format) boards#new
edit_board GET /boards/:id/edit(.:format) boards#edit
board GET /boards/:id(.:format) boards#show
PATCH /boards/:id(.:format) boards#update
PUT /boards/:id(.:format) boards#update
DELETE /boards/:id(.:format) boards#destroy
And also the value of params at the start of topics_controller#create
{"utf8"=>"✓", "authenticity_token"=>"...", "topic"=>{"title"=>"New Title", "post"=>{"content"=>"New Content"}},"commit"=>"Post new topic", "action"=>"create", "controller"=>"topics", "board_id"=>"1"}
回答1:
Finally found the solution here
This was after I fixed the form to create the params correctly.
Basically, I needed to use :inverse_of on my models. I don't really understand what this accomplishes but it works. Here's my code
topic.rb
class Topic < ActiveRecord::Base
belongs_to :user
belongs_to :board
has_many :posts, :inverse_of => :topic
accepts_nested_attributes_for :posts
validates :title, presence: true, length: { maximum: 255 }
validates :user, presence: true
validates :board, presence: true
end
post.rb
class Post < ActiveRecord::Base
belongs_to :user
belongs_to :topic, :inverse_of => :posts
validates :user, presence: true
validates :topic, presence: true
validates :content, presence: true
end
app/views/topics/new.html.erb
<div>
<%= form_for [@board, @topic] do |f| %>
<%= render 'shared/error_messages', object: @topic %>
<%= f.label :title %>
<%= f.text_field :title %>
<%= f.fields_for :posts do |p| %>
<!-- I needed to pass in the current_user.id for the post -->
<%= p.hidden_field :user_id, :value => current_user.id %>
<%= p.label :content %>
<%= p.text_area :content %>
<% end %>
<%= f.submit "Post new topic", class: "button submit" %>
<% end %>
</div>
app/controllers/topics_controller.rb
def create
@board = Board.find(params[:board_id])
@topic = @board.topics.build(topic_params.merge({user_id: current_user.id}))
debugger
if @topic.save
flash[:success] = "Topic created"
redirect_to @topic
else
render 'new'
end
end
private
def topic_params
params.require(:topic).permit(:title, posts_attributes: [:content, :user_id])
end
来源：https://stackoverflow.com/questions/25211089/i-cant-create-model-objects-using-accepts-nested-attributes-for-it-wont-creat