为何Rails Composer仅生成基础应用无功能？报404错误

Hey there, let's break down what's going wrong with your Rails Composer setup and get you back on track:

First, the root cause of that 404 error #

The OpenURI::HTTPError you're seeing is almost definitely because the template URL you're using is either truncated (your command cuts off at compos...) or no longer valid. Rails can't fetch the template file from a broken/missing URL, so it just falls back to creating a basic Rails app instead of applying the Composer customizations.

Step-by-step fixes to try #

1. Use the full, correct template URL #

First, make sure you're using the complete, up-to-date URL for the Rails Composer template. For the official RailsApps repo, the proper full link points to the template.rb file in the master branch. Double-check there are no typos or truncated parts in your command—here's what a valid command should look like:

rails new rails-devise-roles -m https://raw.githubusercontent.com/RailsApps/rails-composer/master/template.rb

2. Fall back to a local template file #

If the remote URL still throws a 404, you can download the template file manually and use it locally:

• Grab the template.rb file from the Rails Composer repo and save it to your working directory
• Run the rails new command pointing to your local file instead:

  rails new rails-devise-roles -m ./template.rb
  

3. Check Rails version compatibility #

Older versions of Rails Composer might not play nice with the latest Rails releases (like Rails 7+). If you're using a newer Rails version, try specifying an older, compatible version when creating your app. For example, if the template supports Rails 6.1:

rails _6.1.7_ new rails-devise-roles -m https://raw.githubusercontent.com/RailsApps/rails-composer/master/template.rb

4. Verify the template is loading properly #

When you run the correct command, you should see a series of interactive prompts asking you to select features (like adding Devise, role management, etc.). If you don't see these prompts, the template isn't being loaded at all—double-check your URL or local file path again.

A backup plan if Rails Composer isn't working #

If you keep hitting walls with Rails Composer, you can always add the features manually. For example:

• Add Devise for authentication by running bundle add devise then rails generate devise:install
• Add role management with a gem like cancancan or pundit, and set up a role column in your User model

This approach gives you more control, especially if you're working with a newer Rails version that the template doesn't support.

内容的提问来源于stack exchange，提问作者Owen