I just switched from PHP to Ruby on Rails and was wondering if there was a way to detect the clients device/user agent (reading the HTTP header) in order to serve different versions of the site depending on the request it gets. In PHP I have been using Mobile Detect to do so. The general idea is to only serve files that are needed for each particular version. Thats why a client side approach is not that effective.
Is there a way to do something similar with Ruby 2.0.0 and Rails 4.0.0 ?
Maybe there is a gem to handle cases like that?
Check the request method, where you can get a ActionDispatch::Request where you have all the request parameters, including the user agent.
request.user_agent
Related
I use rack-reverse-proxy to setup my Blogger.com to a subdomain of my Ruby on Rails app: pulpoludo.com/blog
It's work, but I have an issue with the link of Blogger which returns to blog.pulpoludo.com (where my Blogger blog is host).
I would like to rewrite this link. But I don't know-how. Can you help me?
(I have found someone who does this in PHP: https://matt-stannard.blogspot.com/2013/02/blogger-in-subdirectory-of-my-domain.html
But I would like to do the same thing with Rails and a gem maybe)
Indeed, you cannot use rack-reverse-proxy because it does not allow you to change the response (you need to rewrite the page you retrieve using a regular expression replacement, as in the example you link to.
Also, you should probably avoid using rack-reverse-proxy in production, as it will keep your ruby processes busy waiting for the backend responses, that might fail or be slow. And:
It is not meant for production systems
You should instead proxy from your front HTTP acceptor (nginx or other). For nginx you can see a very thorough response, using a combination of proxy_pass and sub_filter, at https://stackoverflow.com/a/32543398/384417.
edit: If it's not possible to use nginx or another reverse proxy, you can still do it in ruby.
rack-reverse-proxy supports transformers, you can build one yourself, and register it so it's run on the response. This (closed) issue will help, it is exactly what you need: https://github.com/waterlink/rack-reverse-proxy/issues/65. The caveat (as always when changing responses) is that you have to update the Content-Length response header to match the updated size of the body.
I managed to write a ruby script which uses capybara (Capybara.current_session.driver.browser.manage.all_cookies) to read the cookie from a browser. I could not find methods to read the complete request headers of a API. Like Method, Content-Type, Accept-language, CSRF etc.
Can someone shed some lights please!
tl;dr; You shouldn't be using Capybara to write API tests
You're using the wrong tool for the job. Capybara is designed to test an application from the users perspective. Since a user doesn't really care about things like headers (just the affect they have in the browser) Capybara doesn't provide them. It's also why you had to go so far down in driver specific methods to get cookies - you really shouldn't be directly accessing those in Capybara driven tests either, just testing the behaviors the cookies control happen.
I am experimenting with websockets in my ruby on Rails server. I am trying faye-websocket as described in here.
Initial tests look promising (I am using a python client and I am able to connect to the websocket) but I have a newbie question that keeps bugging me. Including my websockets library as a middleware in ruby seems to capture ALL requests from my client that are websocket connections. In such case, how do I differentiate (and reply differently) to client calls with different routing (e.g. calls to http://myserver.com/apple and http://myserver.com/pear being both websockets)?
EDIT
I found that the env variable contains the field "REQUEST_PATH" which has the information of the routing requested by the client. I can use that variable to return the appropriate answer to each one of the different client calls. Is there any more "elegant" way to do it?
I'm having trouble figuring out how to do this using Rails, though it is probably cause I don't know the proper term for it.
I basically want to do this:
def my_action
sleep 1
# output something in the request, but keep it open
print '{"progress":15}'
sleep 3
# output something else, keep it open
print '{"progress":65}'
sleep 1
# append some more, and close the request
print '{"sucess":true}'
end
However I can't figure out how to do this. I basically want to replicate a slow internet connection.
I need to do this because I am scraping websites, which takes time, where I am 'sleeping' above.
Update
I'm reading this using iOS, so I don't want a websocket server, I think.
Maybe this is exactly what you're looking for:
Infinite streaming JSON from Rails 3.1
You probably want to do some reading around HTML5 WebSockets (there are backwards compatible hacks for older browsers) which let you push data to the client from the server.
Rails has a number of ways to implement a WebSockets server. This question gives some of the options Best Ruby on Rails WebSocket tool
If that would work on the server-side, how would you handle it on the client-side?
HTTP requests normally can just have one response (which may be chunked when using streaming, which wouldn't work in your case I think).
I guess you would either have to look into websockets or make separate requests for each step.
I would like to use the plugin em-eventsource ( https://github.com/AF83/em-eventsource ) for server-sent events in a Rails 3.1-project. My problem is, that there is only explained how to listen on events and receive messages, but not how to fire a specific event up and send the message. I would like to produce the event in an Active Record-Observer. Am I right when I think that I have to defer a operation with EventMachine to produce this event, or how can I solve this?
And yes, it has to be Ruby on Rails. If I don't get this to work with EventMachine, I would try to bypass the whole ruby-part with node.js.
Actually I worked on this library a little with the maintainer. I think you mixed the client part with the server one. em-eventsource is a client library which you can use to consume a ServerSentEvent API, it's not meant to fire SSE.
On the server side, it quite doesn't matter whether you are using Rails or any other stack (nodejs, php…) as long as the server you are running on supports streaming. The default web server shipped with Rails does not (Webrick) but there are many others which do: Thin, Puma, Goliath…
In order to fire SSE in Rails, you would have to use both a streaming-capable server among those cited, and abide by the SSE specification. It mostly falls down to, first, responding with the proper Content-type header ("text/event-stream") so that the client (browser) knows it should hang-on, and then start streaming on the socket. That latter part is the one not easily possible as of today in Rails 3 (yet not impossible!); Rails 4 actually now supports streaming in an easy way, with a clean and simple internal API, so it's definitely coming.
In the mean time, you'd either:
mess with Rack's API in Rails (using EventMachine I guess, there are some examples in the wild)
or have it smart and make use of the streaming feature provided by Sinatra, built on top of Rack (see https://gist.github.com/1476463 for an example of Sinatra app which can be mounted in a Rails one!)
or you could use an external service such as Pusher
or leverage a entirely different stack…
A good overview: http://blog.phusion.nl/2012/08/03/why-rails-4-live-streaming-is-a-big-deal/
Maybe I'm wrong, but if IIRC Rails can't support long pooling. Rails block whole server (or thread if you have more than one running inside server) for each request and can't reuse them unless whole response was send. That's why you should setup reverse proxy (like nginx) in front of Rails application if you suspect there could be many concurrent connections - to proxy slow client requests and send them to Rails when whole request is received. It's just how Rack works, there's not much you can do about this probably.