Re: Rails Default ETag Generation

[Frederick Cheung]

On Tuesday, October 2, 2012 9:50:39 PM UTC+1, jcoleman wrote:

How does Rails generate ETags by default? I've got config.action_controller.perform_caching set to true in production so that I can use page-level caching in a few specific places, but it seems that Rails is automatically setting ETags on *all* responses even though I'm not using fresh_when or the stale? helpers in any of my actions. How is Rails deciding to do this and how do I disable it without killing page caching?

The Rack::Etag middleware  does this, using an MD5 of the response body as the actual etag. I would have thought that removing Rack::ETag from the middleware stack would hobble this.

Fred

[jcoleman]

Is there a way to disable certain middleware based on the route? Part of my application is an API that shouldn't really ever be sending 304's while I'm fine with the web application doing that. It seems like removing Rack::ConditionalGet should eliminate the setting of the 304 when the ETags match, but I don't see a way in the documentation to remove middleware non-globally.

[Frederick Cheung]

On Wednesday, October 3, 2012 2:11:33 PM UTC+1, jcoleman wrote:

Is there a way to disable certain middleware based on the route? Part of my application is an API that shouldn't really ever be sending 304's while I'm fine with the web application doing that. It seems like removing Rack::ConditionalGet should eliminate the setting of the 304 when the ETags match, but I don't see a way in the documentation to remove middleware non-globally.

I don't think so, at least not without splitting out your api into an engine which would then (IIRC - engines aren't something I've really used) have its own middleware stack.

It should however be relatively easy to write your own middleware  which, depending on the path, either calls through to the next item in the stack or invokes the Rack::Etag stuff and then replace the Rack::Etag middleware with that

Fred

[jcoleman]

I ended up inserting my own middleware before Rack::Cache (which was actually causing the issue--I'd even tried removing Rack::ConditonalGet and the issue was still happening) that removes the If-None-Matches and If-Modified-Since headers on the matching requests.

Thanks for the help!