Webpacker can't find application

问题

I'm creating a new rails application according to "Getting Started with Rails". The application starts normally in step 4.1. But when i create my first controller, i have a webpack error.

I'm new in webpack, i have red all documentation, but i don't understand what is wrong or missing...

Windows 10 1903
ruby 2.6
rails 6.0.0
nodeJS 12.11.0

rails webpacker:install
   identical  config/webpacker.yml
Copying webpack core config
       exist  config/webpack
   identical  config/webpack/development.js
   identical  config/webpack/environment.js
   identical  config/webpack/production.js
   identical  config/webpack/test.js
Copying postcss.config.js to app root directory
   identical  postcss.config.js
Copying babel.config.js to app root directory
   identical  babel.config.js
Copying .browserslistrc to app root directory
   identical  .browserslistrc
The JavaScript app source directory already exists
       apply  C:/Ruby26-x64/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/install/binstubs.rb
  Copying binstubs
       exist    bin
   identical    bin/webpack
   identical    bin/webpack-dev-server
      append  .gitignore
Installing all JavaScript dependencies [4.0.7]
         run  yarn add @rails/webpacker from "."
yarn add v1.17.3
[1/4] Resolving packages...
[2/4] Fetching packages...
info fsevents@1.2.9: The platform "win32" is incompatible with this module.
info "fsevents@1.2.9" is an optional dependency and failed compatibility check. Excluding it from installation.
[3/4] Linking dependencies...
warning " > webpack-dev-server@3.8.2" has unmet peer dependency "webpack@^4.0.0".
warning "webpack-dev-server > webpack-dev-middleware@3.7.2" has unmet peer dependency "webpack@^4.0.0".
[4/4] Building fresh packages...
success Saved 1 new dependency.
info Direct dependencies
└─ @rails/webpacker@4.0.7
info All dependencies
└─ @rails/webpacker@4.0.7
Done in 4.48s.
Installing dev server for live reloading
         run  yarn add --dev webpack-dev-server from "."
yarn add v1.17.3
[1/4] Resolving packages...
[2/4] Fetching packages...
info fsevents@1.2.9: The platform "win32" is incompatible with this module.
info "fsevents@1.2.9" is an optional dependency and failed compatibility check. Excluding it from installation.
[3/4] Linking dependencies...
warning "webpack-dev-server > webpack-dev-middleware@3.7.2" has unmet peer dependency "webpack@^4.0.0".
warning " > webpack-dev-server@3.8.2" has unmet peer dependency "webpack@^4.0.0".
[4/4] Building fresh packages...
success Saved 1 new dependency.
info Direct dependencies
└─ webpack-dev-server@3.8.2
info All dependencies
└─ webpack-dev-server@3.8.2
Done in 4.92s.
Webpacker successfully installed �🎉🍰🍰

Webpacker::Manifest::MissingEntryError in Welcome#index

Showing C:/Users/[...]/site_test/app/views/layouts/application.html.erb where line #9 raised:

Webpacker can't find application in C:/Users/[...]/site_test/public/packs/manifest.json. Possible causes:
1. You want to set webpacker.yml value of compile to true for your environment
   unless you are using the `webpack -w` or the webpack-dev-server.
2. webpack has not yet re-run to reflect updates.
3. You have misconfigured Webpacker's config/webpacker.yml file.
4. Your webpack configuration is not creating a manifest.
Your manifest contains:
{
}

Extracted source (around line #9):

7
8      <%= stylesheet_link_tag 'application', media: 'all', 'data-turbolinks-track': 'reload' %>
9      <%= javascript_pack_tag 'application', 'data-turbolinks-track': 'reload' %>
10 </head>
11 <body>
12

回答1:

This error seems to be the key.

Your manifest contains:
{
}

Try simply running the yarn command in your project directory. That should result in a manifest.json file being created - among other things.

If that doesn't work, I found this issue on github from which I am verbatim reciting the following commands that may help you. This will reset all built assets and node_modules.

rm -rf node_modules
rails assets:clobber
yarn
rails assets:precompile

Check out that link for more information.

回答2:

run the command

rails webpacker:install

This solved the problem for me.

回答3:

I got this error message on a Rails 5.2 app where I added Webpacker per the instructions in its README.

After trying some other things, I tried starting webpacker-dev-server (even though it shouldn't be necessary) just to see if that would show a more helpful error. And it did:

$ ./bin/webpack-dev-server
warning package.json: No license field
Another program is running on port 3035. Set a new port in  for dev_server

I then switched to another project I had running, which also uses Webpacker, and turned off its webpack-dev-server (just ctrl+c:ed the running server). Now when I reload a page in this new project, I no longer get the error. Even without me running webpack-dev-server manually.

You can change this port in config/webpacker.yml, in the dev_server: section. Don't forget to also update it in config/initializers/content_security_policy.rb if necessary.

回答4:

I got this same error - fix for me: I had a NODE_ENV environment variable set in my .zshrc file that was causing the Webpack build to use the wrong environment config, unsetting that environment variable fixed it for me (unset NODE_ENV)

回答5:

Thanks for your help. Unfortunately nothing works.

rails assets:clobber return "error Couldn't find an integrity file" immediatly after deleting node_modules folder. (Works after yarn install --check-files).

and rails assets:precompile return "C:/Ruby26-x64/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/webpack_runner.rb:23:in `exec': No such file or directory - C:\Users[...]\site_test\node_modules.bin/webpack (Errno::ENOENT)"

but i found what was wrong: the location in my computer! probably a name problem ...

来源：https://stackoverflow.com/questions/58270161/webpacker-cant-find-application

标签

ruby-on-rails

Webpack

ruby-on-rails-6