问Active Admin外键关系无方法错误

EN

class Note < ApplicationRecord
  belongs_to :content
end

class Content < ApplicationRecord
    has_many :notes
end

ActiveAdmin.register Content do
    permit_params :name, note_ids: []

show title: 'Test' do
    h3 'You have ' + pluralize(content.notes.count, 'note') + ' referencing ' + `#{content.name}`
end

ActiveRecord::Schema.define(version: 2021_05_06_140826) do

  # These are extensions that must be enabled in order to support this database
  enable_extension "plpgsql"

  create_table "active_admin_comments", force: :cascade do |t|
    t.string "namespace"
    t.text "body"
    t.string "resource_type"
    t.bigint "resource_id"
    t.string "author_type"
    t.bigint "author_id"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    t.index ["author_type", "author_id"], name: "index_active_admin_comments_on_author_type_and_author_id"
    t.index ["namespace"], name: "index_active_admin_comments_on_namespace"
    t.index ["resource_type", "resource_id"], name: "index_active_admin_comments_on_resource_type_and_resource_id"
  end

  create_table "admin_users", force: :cascade do |t|
    t.string "email", default: "", null: false
    t.string "encrypted_password", default: "", null: false
    t.string "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    t.index ["email"], name: "index_admin_users_on_email", unique: true
    t.index ["reset_password_token"], name: "index_admin_users_on_reset_password_token", unique: true
  end

  create_table "contents", force: :cascade do |t|
    t.string "name"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
  end

  create_table "notes", force: :cascade do |t|
    t.string "title"
    t.text "body"
    t.bigint "content_id", null: false
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    t.index ["content_id"], name: "index_notes_on_content_id"
  end

  add_foreign_key "notes", "contents"
end