Asset Pipeline: Asset attempted to compress while creating page response & not during asset request


I am stuck in a weird situation where in my production environment, an asset is being attempted to compress while rendering a view.

I’ve all my assets put into public/assets folder via rake “assets:precompile”

production.rb has following configurations:

I’m not surprised it is re-compiling the source code at runtime. You have to be careful with javascript_include_tag when you are using the asset pipeline. When you precompile your assets, everything is put into one js file with a long, cryptic name that looks something like the following in html:

When you then insert a javascript tag, it’s going to look like the following in your html:

The browser is going to attempt to load both files. It doesn’t detect that the contents of jquery.bxslider.min.js are actually already in the first file. Because this file is located in the /app/assets/js directory, it’s going to be processed by rails through the asset compiler when the browser requests the file.

You shouldn’t reference a javascript file in a script tag if you’ve already included it in the asset pipeline unless you truly intend to load it twice.

If you have javascript you want to load independent of the asset pipeline and you don’t want it processed through the asset compiler, you should reference it in a javascript_include_tag as you have done above, but you should locate the file in the public/js directory.

Thanks for the update.

jquery.bxslider.min.js in my case is not part of application.js

I have added jquery.bxslider.min.js to pre-compile path also, so that it can be loaded independently.

Its available in public/assets folder too.

You said “I’m not surprised it is re-compiling the source code at runtime.”…I totally agree.

However that should happen when browser request that very particular asset, not while creating page response that has

in the markup.

Am I going astray here in making you understand the issue.

Let me know.

Following are the configurations in my production.rb file:

Disable live compilation of assets(Don’t fallback to assets pipeline if a precompiled asset is missed)

config.assets.compile = false

Assets pre-compilation task(rake assets:precompile) configurations

config.assets.css_compressor = :yui

config.assets.js_compressor = :yui

config.assets.compress = true

Let me know, if these configs are specified correctly.

You’re right, I didn’t fully understand the issue. The settings in your production.rb are typical production settings. However, in this case, the first setting, config.assets.compile = false has implications.

When this is set to false, the system assumes all assets have been pre-compiled. When you pre-compile, a manifest is generated that maps the “normal” file names to the cryptic filename it’s now compressed into. When html code is generated from a view, it references the manifest, and substitutes the cryptic filename.

This is the point where I’m unsure of what happens. In your case, there’s a file referenced in the assets directory that isn’t in the manifest and isn’t pre-compiled. I’m not sure what the system does because when this flag is set to false, it doesn’t even load the pipeline gems so it doesn’t have access to the compiler. I’m guessing it throws an error, but that’s a guess, which would be the error you encountered.

I’d have to test this but my guess is that you either need to pre-compile the asset, or locate it in the public directory (only) and write the tag to access the file in the public directory.

I’m not sure this is correct, but hopefully it will point you in the right direction.


Thanks for enlightenment :slight_smile:

I shall perform some ups and downs.

Will let you know, if I get any new insight



With config.assets.compile = false(live compilation disabled)

I removed entry from manifest.yml file and I got:

ActionView::Template::Error (jquery.bxslider.min.js isn’t precompiled)

which I guess it valid error message.

Had there been, config.assets.compile = true + missing mappin in manifest

and no java to support YUI gem to compress.

Not sure what would happen.