Rails-一个视图中有2个模型（属于属于另一个模型的模型）

Question

There were several questions and answers for this, except that every time the model view used the opposite of what I need. In my case, I have 3 models that I want to display in one View. Post belongs_to Username , Username has_many Posts . The third model I have is Category has_many Posts , which displays correctly through collection select. The view is of Post model, _form.html.erb

<%= form_for(@post) do |f| %>
  <%= f.label :equipment %><br />
  <%= f.text_field :equipment %><br />
  <%= f.label 'Serial number' %><br />
  <%= f.text_field :serial_num %><br />
  <%= f.label :category %><br />
  <%= collection_select(:post, :category_id, Category.all, :id, :name, prompt: true) %>

  <%= f.fields_for :usernames do |user| %>
    <%= user.label :username %><br />
    <%= user.text_field :name %>
  <% end %>

<% end %>

That is what I want to do - to display username.name (in post I have FK username_id). The above code fields_for doesn't work, it displays nothing. All the answers on this question that I found are in the view of has_many model, while I need this in the view of belongs_to model. So, how can I access name attribute of Username model that has_many Posts in post view? (So far I can only access foreign key, which is in Post model).

post.rb

class Post < ActiveRecord::Base
  attr_accessible :category_id, :equipment, :serial_num, :username_id
  belongs_to :category
  belongs_to :username
  validates :username_id, :presence => true
end

username.rb

class Username < ActiveRecord::Base
  attr_accessible :name
  has_many :posts
  validates :name, :presence => true
end

routes.rb

resources :usernames
resources :categories
resources :posts

Please help!

Answer 1

accepts_nested_attributes_for :username  

in your post.rb

But don't you want the post to automatically be assigned to the current_user?????