如何在Rails 4.2.6应用中使用通配符预编译资产？

Hey there, let’s work through this asset precompilation issue you’re hitting. I’ve run into similar headaches with Rails 4.x’s asset pipeline, so here’s a breakdown of what’s going wrong and how to fix it:

Why Your Current Setup Isn’t Working #

First, let’s unpack the two problems:

• The ['*.js', '*.css'] wildcard only matches files directly in the root of app/assets/stylesheets/ and app/assets/javascripts/—it doesn’t recursively look into your module subdirectories.
• The Sass::SyntaxError is almost certainly because your wildcard is picking up partial files (those starting with an underscore, like _base.scss). Partials are meant to be @imported into other stylesheets, not compiled on their own. They often depend on variables/mixins from other files that aren’t loaded when you compile them standalone.

Solution 1: Use Recursive Wildcards (and Exclude Partials) #

If you want to stick with wildcards, you need to target files in subdirectories explicitly and avoid partials. Update your config/initializers/assets.rb like this:

# Keep default precompile rules, then add our recursive matches
config.assets.precompile += [
  # Match all non-partial JS/CSS in root and 1-level subdirs
  '*.js', '*.css',
  '*/*.js', '*/*.css',
  # Add more levels if you have nested subdirs (e.g., */*/*.js)
]

# OR, a more dynamic approach to cover all nested subdirs (avoids hardcoding levels)
config.assets.precompile += Dir[Rails.root.join('app/assets/stylesheets/**/[^_]*.css')]
config.assets.precompile += Dir[Rails.root.join('app/assets/javascripts/**/[^_]*.js')]

The [^_]* pattern ensures we only pick files that don’t start with an underscore (so no partials). Using += instead of = is critical here—it preserves Rails’ default precompile rules for fonts, SVGs, etc., which you’d lose if you overwrite the array entirely.

Solution 2: Use Manifest Files (Recommended) #

The cleaner, more Rails-idiomatic approach is to use manifest files for each module. This aligns with how the asset pipeline is designed and avoids partial-related errors:

1. Create a manifest for each module:
   For example, if you have an admin subdirectory in stylesheets, make app/assets/stylesheets/admin_manifest.css with:

   // Import all partials in the admin module
   @import "admin/base";
   @import "admin/dashboard";
   @import "admin/users";
   

   Do the same for JS: app/assets/javascripts/admin_manifest.js with //= require admin/* (or explicit requires if you prefer).

2. Precompile only the manifests:
   Update config/initializers/assets.rb to target these top-level manifest files:

   config.assets.precompile += [
     'admin_manifest.css', 'admin_manifest.js',
     'frontend_manifest.css', 'frontend_manifest.js'
     # Add other module manifests here
   ]
   

This way, you’re only compiling the files that are meant to be standalone, and partials are properly imported where they belong—no more Sass syntax errors.

Quick Troubleshooting Tip #

If you still get Sass errors, double-check that none of the files you’re precompiling are partials. Run this command to see exactly which files Rails is trying to precompile:

RAILS_ENV=production rake assets:precompile --trace

The trace will show you the specific file causing the error, so you can adjust your precompile rules accordingly.

内容的提问来源于stack exchange，提问作者Steven Aguilar