Mongoid - Rails - Could not find generator 'mongoid:config'

Question

I am new to Rails and am trying to install mongoid. I have followed the exact steps mentioned in the MongoDB documentation, ie:

• gem install rails -v '~> 7'
• rails new myapp --skip-active-record
• cd myapp
• then added gem 'mongoid' to my Gemfile
• and then bundle install

but I am getting the following error:

Could not find generator 'mongoid:config'.

Here is my Gemfile:

source "https://rubygems.org"

ruby "3.1.4"

# Bundle edge Rails instead: gem "rails", github: "rails/rails", branch: "main"
gem "rails", "~> 7.1.1"

# The original asset pipeline for Rails [https://github.com/rails/sprockets-rails]
gem "sprockets-rails"

# Use the Puma web server [https://github.com/puma/puma]
gem "puma", ">= 5.0"

# Add support for mongo
gem 'mongoid'

# Use JavaScript with ESM import maps [https://github.com/rails/importmap-rails]
gem "importmap-rails"

# Hotwire's SPA-like page accelerator [https://turbo.hotwired.dev]
gem "turbo-rails"

# Hotwire's modest JavaScript framework [https://stimulus.hotwired.dev]
gem "stimulus-rails"

# Build JSON APIs with ease [https://github.com/rails/jbuilder]
gem "jbuilder"

# Use Redis adapter to run Action Cable in production
# gem "redis", ">= 4.0.1"

# Use Kredis to get higher-level data types in Redis [https://github.com/rails/kredis]
# gem "kredis"

# Use Active Model has_secure_password [https://guides.rubyonrails.org/active_model_basics.html#securepassword]
# gem "bcrypt", "~> 3.1.7"

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem "tzinfo-data", platforms: %i[ windows jruby ]

# Reduces boot times through caching; required in config/boot.rb
gem "bootsnap", require: false

group :development, :test do
  # See https://guides.rubyonrails.org/debugging_rails_applications.html#debugging-with-the-debug-gem
  gem "debug", platforms: %i[ mri windows ]
end

group :development do
  # Use console on exceptions pages [https://github.com/rails/web-console]
  gem "web-console"

  # Add speed badges [https://github.com/MiniProfiler/rack-mini-profiler]
  # gem "rack-mini-profiler"

  # Speed up commands on slow machines / big apps [https://github.com/rails/spring]
  # gem "spring"

  gem "error_highlight", ">= 0.4.0", platforms: [:ruby]
end

group :test do
  # Use system testing [https://guides.rubyonrails.org/testing.html#system-testing]
  gem "capybara"
  gem "selenium-webdriver"
end

Any idea how to solve this?

Thanks,

Answer 1

Being new to Rails I have been slightly misled by the Mongo docs that indicate that the version 9.0 is available.

The current version of mongoid (8.1.2) only support Rails 7.0.x, and not yet 7.1.

I downgraded Rails to 7.0.8 and restarted the process from scratch.

Things are now working ✅