我在使用实际模型时遇到问题，尝试创建用户时出现以下错误：

app/models/user.rb:1:in `<top (required)>': uninitialized constant ApplicationRecord (NameError)

我在models/application_record.rb中有以下文件
这看起来像：

class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true
end

当我将用户类改为从activerecord:：base继承时，我得到了相同的错误，除了activerecord。
my application.rb：

class Application < Rails::Application

    config.load_defaults 6.1

    config.generators.system_tests = nil
  end

我使用的是rails 6.1。
我的档案：

ruby '2.6.3'
gem 'activerecord'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails', branch: 'main'

gem 'rails', '~> 6.1.4'

# Use sqlite3 as the database for Active Record

gem 'sqlite3', '~> 1.4'

# Use Puma as the app server

gem 'puma', '~> 5.0'

# Use SCSS for stylesheets

gem 'sass-rails', '>= 6'

# Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker

gem 'webpacker', '~> 5.0'

# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks

gem 'turbolinks', '~> 5'

# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder

gem 'jbuilder', '~> 2.7'

# Use Redis adapter to run Action Cable in production

# gem 'redis', '~> 4.0'

# Use Active Model has_secure_password

# gem 'bcrypt', '~> 3.1.7'

# Use Active Storage variant

# gem 'image_processing', '~> 1.2'

# Reduces boot times through caching; required in config/boot.rb

gem 'bootsnap', '>= 1.4.4', require: false

group :development, :test do
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
end

group :development do
  # Access an interactive console on exception pages or by calling 'console' anywhere in the code.
  gem 'web-console', '>= 4.1.0'
  # Display performance information such as SQL time and flame graphs for each request in your browser.
  # Can be configured to work on production as well see: https://github.com/MiniProfiler/rack-mini-profiler/blob/master/README.md
  gem 'rack-mini-profiler', '~> 2.0'
  gem 'listen', '~> 3.3'
  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
  gem 'spring'
end

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem

gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

发生了什么事？我没有拼写错误，模型是user.rb，我不知道发生了什么。
我找到的所有建议