Skip to main content

JSON caching with Rails

So the other day, I needed to cache an action which was basically a proxy action to return JSON.

Basically, 3rd party company X has an XML API for it's deals. Ideally we would use JavaScript to pull the feed, but unfortunately, the feed is using XML which means we need to use the server to pull this "deal" and then reformat it in JSON for our site to use.

To render the JSON we were using a render call


render offer.to_json


It can get expensive to pull this deal over the wire every time, so we looked into using caches action and set it to expire in 5 minutes (because that is how often the deal feed updates).


caches_action :index, :expires_in => 5.minutes


(Oh, also we need to turn caching on in dev to see this happening)


config.action_controller.perform_caching = true


While this worked fine for the first call, I noticed that in the subsequent calls, the application type was being set to 'text/html' instead of 'application/json'. This was causing the AJAX call to fail. I then noticed that the AJAX call was calling the action directly instead of using the .json suffix.

i.e.
/offers/1234

instead of

/offers.json/1234

So it appeared that because I was not using the suffix, the cache was forcing the application/type header to text/html.

In any case, after a quick update to the JavaScript call, the caching worked fine.

Comments

unsymbol said…
How did you change the js to fix this? I'm having a similar issue but with serving js for ajax requests.
Anonymous said…
Where the url used to point to "/offers" I updated it to point to "/offers.json" instead.
Anonymous said…
Hey thanks for the great info... i was looking for same...
Anonymous said…
Hey thanks for great info..

Popular posts from this blog

Freezing Gems

What is a gem and why would you want to freeze it? In Ruby, there are times when you want to access pieces of functionality that other people of written (3rd party libraries) and you normally have 2 options. You can install a plug in or install a gem. Normally the method you use is determined by which ever is made available by the author. Gems are installed on the host machine and are pretty handy when you want to run things in the command line or else across lots of projects, but their downside is that if you use a gem in a Rails project there is no automatic publishing mechanism when you deploy your site. You will need to log onto the remote host machine and install the gem manually. Plugins are specific to Rails and are similar to gems in that they are also 3rd party libraries. However they are associated with your Rails project as opposed to your machine so they will get posted to the server on a regular deploy. Freezing a gem is the process of transforming a gem into a plug in. Es

Elixir - destructuring, function overloading and pattern matching

Why am I covering 3 Elixir topics at once? Well, perhaps it is to show you how the three are used together. Individually, any of these 3 are interesting, but combined, they provide you with a means of essentially getting rid of conditionals and spaghetti logic. Consider the following function. def greet_beatle(person) do case person.first_name do "John" -> "Hello John." "Paul" -> "Good day Paul." "George" -> "Georgie boy, how you doing?" "Ringo" -> "What a drummer!" _-> "You are not a Beatle, #{person.first_name}" end end Yeah, it basically works, but there is a big old case statement in there. If you wanted to do something more as well depending on the person, you could easily end up with some spaghetti logic. Let's see how we can simplify this a little. def greet_beatle(%{first_name: first_name}) do case first_name d

Responsive Web Design

I wanted to go over Responsive Web Design using CSS. In the old days of web development, we had to code to common screen sizes (i.e. 800 X 600, 1024 X 768) and we patiently waited for people to upgrade their computers to have a decent amount of screen real estate so we could design things the way we really wanted. We also took on semi stretchy web layouts etc to expand and contract appropriately. Then about 2 or 3 years ago, Apple released this little device called an iPhone with a 320 X 480 resolution which took the world by storm and suddenly a lot of people were viewing your website on a tiny screen again... Anyways, as it can be difficult to design a site which looks good on 320 X 480 AND 1680 X 1050, we need to come up with some kind of solution. One way is to sniff the client and then use an appropriate stylesheet, but then you are mixing CSS with either JavaScript or server side programming and also potentially maintaining a list of appropriate clients and stylesheets. Also, you