Page caching is a Rails mechanism which allows the request for a generated page to be fulfilled by the webserver (i.e. apache or nginx), without ever having to go through the Rails stack at all. Obviously, this is super-fast. Unfortunately, it can't be applied to every situation (such as pages that need authentication) and since the webserver is literally just serving a file from the filesystem, cache expiration is an issue that needs to be dealt with.
Page caching is a Rails mechanism which allows the request for a generated page to be fulfilled by the webserver (i.e. Apache or nginx), without ever having to go through the Rails stack at all. Obviously, this is super-fast. Unfortunately, it can't be applied to every situation (such as pages that need authentication) and since the webserver is literally just serving a file from the filesystem, cache expiration is an issue that needs to be dealt with.
So, how do you enable this super-fast cache behavior?. Simple, let's say you have a controller called +ProductsController+ and an +index+ action that lists all the products.
To enable page caching, you need to use the +caches_page+ method.
<ruby>
class ProductsController < ActionController
...
...
@@ -35,11 +35,10 @@ class ProductsController < ActionController
def index
@products = Products.all
end
end
</ruby>
The first time anyone requests +/products+, Rails will generate a file called +products.html+ and the webserver will then look for that file before it passes the next request for +/products+ to your Rails application.
Let's say you have a controller called +ProductsController+ and an +index+ action that lists all the products. The first time anyone requests +/products+, Rails will generate a file called +products.html+ and the webserver will then look for that file before it passes the next request for +/products+ to your Rails application.
By default, the page cache directory is set to +Rails.public_path+ (which is usually set to the +public+ folder) and this can be configured by changing the configuration setting +config.action_controller.page_cache_directory+. Changing the default from +public+ helps avoid naming conflicts, since you may want to put other static html in +public+, but changing this will require web server reconfiguration to let the web server know where to serve the cached files from.
...
...
@@ -104,7 +103,7 @@ INFO: Action caching runs in an after filter. Thus, invalid requests won't gener
h4. Fragment Caching
Life would be perfect if we could get away with caching the entire contents of a page or action and serving it out to the world. Unfortunately, dynamic web applications usually build pages with a variety of components and not all of which have the same caching characteristics. In order to address such a dynamically created page where different parts of the page need to be cached and expired differently Rails provides a mechanism called Fragment Caching.
Life would be perfect if we could get away with caching the entire contents of a page or action and serving it out to the world. Unfortunately, dynamic web applications usually build pages with a variety of components not all of which have the same caching characteristics. In order to address such a dynamically created page where different parts of the page need to be cached and expired differently, Rails provides a mechanism called Fragment Caching.
Fragment Caching allows a fragment of view logic to be wrapped in a cache block and served out of the cache store when the next request comes in.
