# Unexpected behavior with respond\_to

**URL:** <https://www.ruby-forum.com/t/unexpected-behavior-with-respond-to/192429>\
**Category:** Rails\
**Created:** [July 30, 2010, 8:23am UTC](https://www.ruby-forum.com/t/unexpected-behavior-with-respond-to/192429 "2010-07-30T08:23:11Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Erik\_Hetzner](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/4491bb/32.png) [@Erik\_Hetzner](https://www.ruby-forum.com/u/Erik_Hetzner)\
**Post date:** [July 30, 2010, 8:23am UTC](https://www.ruby-forum.com/t/unexpected-behavior-with-respond-to/192429/1 "2010-07-30T08:23:11Z")

</div>

Hi all,

I am encountering some unexpected behavior in the Rails 3.0.0.rc which  
I think may be incorrect.

In my controller, I have the following:

class FeedsController \< ApplicationController  
def recent  
respond\_to do |format|  
format.atom  
end  
end  
end

Likewise, I have a view (feeds/recent.atom.builder):

xml.tag!(‘feed’, :xmlns =\> “[Atom Syndication Format namespace](http://www.w3.org/2005/Atom)”) do  
xml.text!(“…”)  
end

and I have a route:

match(‘feeds/recent’ =\> ‘feeds#recent’)

If I try to fetch this with no Accept header, I get a 406 error:

$ curl -i [http://localhost:3000/feeds/recent](http://localhost:3000/feeds/recent) -H “Accept:”  
HTTP/1.1 406 Not Acceptable  
[…]

This is probably not correct, since RFC 2616 (sec 14.1) reads:

| If no Accept header field is present, then it is assumed that the  
| client accepts all media types.

Moving on.

If I try to fetch this with an “Accept: _/_” header or “Accept:  
application/atom+xml”, it works as expected. Likewise all works well  
if I use an “Accept: _/_, text/html” header

However, if I change the order of the formats, to “Accept: text/html,  
_/_”, I get a 406:

$ curl -i [http://localhost:3000/feeds/recent](http://localhost:3000/feeds/recent) -H “Accept: text/html,  
_/_”  
HTTP/1.1 406 Not Acceptable  
[…]

But a “text/html, _/_” Accept header should be equivalent to a “_/_,  
text/html” header, since order does not matter. (This is a contrived,  
but similar Accept headers are used by Firefox, with q values.)

Getting further into the bowels of RFC 2616, an “Accept:  
application/\*” header gives me a 406, when it should be acceptable,  
because I have a response of type “application/atom+xml”.

One final thing. I add a format.any entry to the controller (I am not  
entirely sure the meaning of this):

def recent  
respond\_to do |format|  
format.atom  
format.any  
end  
end

And now I get a 200 with “Accept: _/_” and “Accept:  
application/atom+xml”, but template errors with any other Accept  
header including a “_/_”.

Does anybody have any thoughts about this? It does not seem to me that  
Rails is not doing the right thing here.

best, Erik Hetzner

---

<div class="post-metadata">

**Author:** ![Erik\_Hetzner](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/4491bb/32.png) [@Erik\_Hetzner](https://www.ruby-forum.com/u/Erik_Hetzner)\
**Post date:** [September 6, 2010, 4:39pm UTC](https://www.ruby-forum.com/t/unexpected-behavior-with-respond-to/192429/2 "2010-09-06T16:39:57Z")

</div>

I have similar issues with some js.rjs files after upgrading an app to  
rails  
3. Some respond\_to blocks keep working fine as before and I get JS  
returned,  
some keep trying to return HTML and thus spit out the 406 error. I  
haven’t  
found any good reason in my code to justify this kind of behavior, even  
after i tried reducing the affected js.rjs files to a simple  
straightforward  
single line of code: I still get them returned as html with error 406. I  
even tried to enforce javascript headers by putting: format.js {render  
:content\_type =\> ‘text/javascript’} in the respond\_to block, but that  
didn’t  
change it.  
Really stuck on this issue. In 2.3.8 the code worked perfectly fine.