Request.xhr? vs. respond_to

Rails
1

Searched around this forum, but didn’t find an answer for this question.

Can you help this newbie understand any overlap and/or difference
between request.xhr? and respond_to?

If request.xhr? is true, should I expect it wants.js below?
respond_to do |wants|
wants.html { redirect_to(person_list_url) }
wants.js
wants.xml { render :xml => @person.to_xml(:include => @company) }
end

Is it fair to say the functionality of respond_to a super set of
request.xhr?

TIA!

2

short answer: no, not equivalent

longer answer:

– request.xhr? –

check the following header in the request:

    'X-Requested-With' = 'XMLHttpRequest',

this is set automatically by the prototype library

see line 699 in version 1.5.0_rc0

– response_to –

check the ‘Accept’ header. this is set not only by prototype but also
by browser, spiders, etc.

looks something like ‘Accept’, ‘text/html, application/xml,
text/xml, /’]

check

Doug D. schrieb:

3

Thank you, Pete, for the explanation of where they come from!

To implement graceful RJS degradation, does it mean request.xhr? is
sufficient? Or need both? Is it possible that a broswer doesn’t set the
Accept header accordingly? See
http://www.ruby-forum.com/topic/65059#74833

For JS (in general) degradation, however, respond_to is the way to go?

Doug (quite ignorant about Web UI)

Pete wrote:

short answer: no, not equivalent

longer answer:

– request.xhr? –

check the following header in the request:

    'X-Requested-With' = 'XMLHttpRequest',

this is set automatically by the prototype library

see line 699 in version 1.5.0_rc0

– response_to –

check the ‘Accept’ header. this is set not only by prototype but also
by browser, spiders, etc.

looks something like ‘Accept’, ‘text/html, application/xml,
text/xml, /’]

check

Doug D. schrieb:

4

my understanding is that request.xhr? indicates the controller has
received an ajax request, while respond_to indicates that the browser
can accept specific mime types.

non?

Jodi

5

I’m not sure I can speak specifically to degradation…Alas I’m
building for a defined Intranet userbase, so I have more
predictability than the average cat.

I use request.xhr? to target particular responses to the browser - a
partial for ajax, a partial for ‘non-ajax’.

…having said that it makes a certain amount of sense that accepts
(respond_to) would is the appropriate question you want answered :
‘can the browser understand an ajax response’.

so yes, I agree - the latter seems to be the appropriate approach…

though others more experience than me may add to the argument.

good luck Adam.

Jodi

6

Yes. Thank you, Jodi!

Here is my confusion: Doesn’t this mean that if we get request.xhr?
true, RJS will be stuffed back regardless whether the browser accepts
JS? That’s because the request comes from the prototype library. But, I
see JS degradation is implemented with respond_to:
Graceful degrading AJAX show/hide - Rails - Ruby-Forum. But again, another fellow
had some trouble: AJAX request not setting Accept header - Rails - Ruby-Forum

Which one or both should be used to determine what the browser is able
to or want to handle? Perhaps, we should respect just the latter?

Jodi S. wrote:

my understanding is that request.xhr? indicates the controller has
received an ajax request, while respond_to indicates that the browser
can accept specific mime types.

non?

Jodi