Rails 4.2自联接模型-Create方法返回错误

Question

I have a simple self-join model for an Account. An Account can have a single parent and/or multiple child Accounts.

Here is the class:

class Account < ActiveRecord::Base
  has_many :children, class_name: "Account", foreign_key: "parent_id"
  belongs_to :parent, class_name: "Account"
end

and the migration:

class CreateAccounts < ActiveRecord::Migration
  def change
    create_table :accounts do |t|
      t.references :parent, index: true
      t.string :name
      t.string :category
      t.timestamps null: false
    end
  end
end

When the create method is invoked on the controller, I get the following error:

Account(#70188397277860) expected, got String(#70188381177720)

and it references the first line of the create method in the controller:

def create
  @account = Account.new(account_params)

  respond_to do |format|
    if @account.save
      format.html { redirect_to @account, notice: 'Account was successfully created.' }
      format.json { render :show, status: :created, location: @account }
    else
      format.html { render :new }
      format.json { render json: @account.errors, status: :unprocessable_entity }
    end
  end
end

Since the Account model is self-referential, it seems like Rails expects an Account as an argument for constructing an Account.

The Rails ActiveRecord Guide has a limited example which I believe I have followed closely, but I cannot figure out where I am going wrong.

I have tried various permutations foreign key types and what-not with no luck. Any pointers are appreciated.

EDIT:

Here is the form, generated by the scaffold command, that gathers the information for creating a new account. As suggested by @SteveTurczyn in the comments, the form is collecting a string for the parent field instead of an id.

<%= form_for(@account) do |f| %>
  <% if @account.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@account.errors.count, "error") %> prohibited this account from being saved\
:</h2>

      <ul>
      <% @account.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :parent %><br>
    <%= f.text_field :parent %>
  </div>
  <div class="field">
    <%= f.label :name %><br>
    <%= f.text_field :name %>
  </div>
  <div class="field">
    <%= f.label :category %><br>
    <%= f.text_field :category %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

EDIT2:

Changing the parent field from text_field to number_field has no effect on the result.

The parameters passed to the create method are the same:

{"utf8"=>"✓",
"authenticity_token"=>"pq0sp162cA7Bmn7uw67F7gOvUVLj/S+xcasVibqysiF68vheVkATsf4pwKgPqH5nawjc0BnIj3qoot8JyIeVmg==",
 "account"=>{"parent"=>"0",
 "name"=>"Foo",
 "category"=>"Bar"},
 "commit"=>"Create Account"}

I'm a little confused about how this is supposed to work.

Answer 1

You're submitting the ID of a parent from the form, but your association expects parent to actually be an Account object, not the ID of one.

Change the form to submit parent_id instead of parent .