how does rails expire assets?

Question

In application.rb, there is the following:

# Version of your assets, change this if you want to expire all your assets
config.assets.version = '1.0'

I've incremented this to 1.1, but when I reloaded my page live, the old js was still loaded. I looked at the source, expecting to find a GET version parameter appended to the js and css files, but there was no such thing.

<link href="/assets/application.css" media="all" rel="stylesheet" type="text/css" />
<script src="/assets/application.js" type="text/javascript"></script>

What forces the browser to clear its cache?

Answer 1

The version number is only taken into account when creating the md5 fingerprints for your assets.

http://guides.rubyonrails.org/asset_pipeline.html#what-is-fingerprinting-and-why-should-i-care-questionmark

Answer 2

Set:

config.assets.digest = true 

in production.rb. Then when you precompile your stylesheets using:

rake assets:precompile

you'll see the fingerprint has been added to the actual filename, like this:

styles-5b4f282be3720d5b1e40d9e343dfc60a.css

This fingerprint is changed whenever the stylesheet (or other asset) is edited. The changed filename forces the browser to clear it's cache.

Answer 3

You have to be using the asset pipeline. Then include the assets with either asset_path, javascript_include_tag etc. Your get doesn't have the Md5 fingerprint, so either your asset pipeline is not enabled, or you aren't linking to your js correctly.