Rails应用程序中的AssociationTypeMismatch (Object expected，got )

Question

我得到了一个AssociationTypeMismatch错误，我不知道我在哪里出错。我对Rails很陌生，所以我猜我犯了一些愚蠢的错误。我检查了我的语法并将其与AssociationTypeMismatch Error on Ruby on Rails app进行了比较

..。但我似乎还是抓不到这个错误。

这是我的模特

class User < ActiveRecord::Base
  attr_accessible :email, :full_name, :password, :password_confirmation, :preference
  has_secure_password

  validates_uniqueness_of :email
  validates_presence_of :full_name

  has_one :preference, :dependent => :destroy

  accepts_nested_attributes_for :preference
end

class Preference < ActiveRecord::Base
  attr_accessible :background_fill, :background_position, :layout

  belongs_to :user
end

这是我的控制器：

def new
  @user = User.new
  @user.build_preference
end

def create
  @user = User.new(params[:user])
  if @user.save
    session[:user_id] = @user.id
    redirect_to root_url, notice: "Thanks for signing up!"
  else
    render "new"
  end
end

以下是我的看法：

<%= form_for @user do |f| %>
  <% if @user.errors.any? %>
  <div class="error_messages">
    <h2>There's an error!</h2>
    <ul>
      <% @user.errors.full_message.each do |message| %>
        <li><%= message %></li>
      <% end %>
    </ul>
  </div>
  <% end %>
  <%= f.label :full_name %>
  <%= f.text_field :full_name, :class => "target", :placeholder => "Your full name", :maxlength => "55", :autofocus => "autofocus" %>
  <%= f.label :email %>
  <%= f.email_field :email, :class => "target", :placeholder => "example@gmail.com", :maxlength => "55" %>
  <%= f.label :password %>
  <%= f.password_field :password, :class => "target", :placeholder => "Enter a password", :maxlength => "55" %>
  <%= f.label :password_confirmation, "Confirmation" %>
  <%= f.password_field :password_confirmation, :class => "target", :placeholder => "Enter your password again", :maxlength => "55" %>
  <%= f.fields_for :preference do |builder| %>
    <%= builder.hidden_field :layout, value: params[:layout] %>
    <%= builder.hidden_field :background_fill, value: params[:background_fill] %>
    <%= builder.hidden_field :background_position, value: params[:background_position] %>
  <% end %>
  <%= f.submit "Create an Account", :class => "button cta" %>
<% end %>

和我的参数

{"utf8"=>"✓",
"authenticity_token"=>"[redacted]=",
"user"=>{"full_name"=>"test",
"email"=>"test@example.com",
"password"=>"[FILTERED]",
"password_confirmation"=>"[FILTERED]",
"preference"=>{"layout"=>"layout-3",
"background_fill"=>"restaurant-2",
"background_position"=>"position-center"}},
"commit"=>"Create an Account"}

编辑：，我得到的错误是Preference(#70124732528700) expected, got ActiveSupport::HashWithIndifferentAccess(#70124687315200)。我的理解是，@user.build_preference和accepts_nested_attributes_for :preference只会独立工作。

是否需要按照以下方式创建一个def preferences_attributes=？for

更新，好的，我想我会更近一点。在rails控制台中穿插时，我想我需要在UserController中创建UserController，然后才能传递哈希。由于我不确定build_preference到底做了什么，所以我还没有任何运气。

我尝试过将@user.preference = Preference.new添加到构建首选项，并将f.field_for :preference更改为f.field_for @user.preference，但仍然会出现相同的错误。

更新2对于任何其他被困在这个问题上的人来说，答案是将f.field_for :preference更改为f.field_for :preference_attributes。请参阅下面zetetic的评论。

Answer 1

它是：

attr_accessible :preference_attributes

以你的形式：

<%= f.fields_for :preference_attributes do |builder| %>
...

Answer 2

试试看。

在User模型中，尝试将:preference_attributes添加到attr_accessible行。

class User < ActiveRecord::Base
  attr_accessible :email, :full_name, :password, :password_confirmation, :preference_attributes
  .. # rest of your code goes here
end