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Diffstat (limited to 'guides/source/caching_with_rails.md')
| -rw-r--r-- | guides/source/caching_with_rails.md | 36 |
1 files changed, 30 insertions, 6 deletions
diff --git a/guides/source/caching_with_rails.md b/guides/source/caching_with_rails.md index 6c734c1d78..fd7626250c 100644 --- a/guides/source/caching_with_rails.md +++ b/guides/source/caching_with_rails.md @@ -198,11 +198,11 @@ render "comments/comments" render 'comments/comments' render('comments/comments') -render "header" => render("comments/header") +render "header" translates to render("comments/header") -render(@topic) => render("topics/topic") -render(topics) => render("topics/topic") -render(message.topics) => render("topics/topic") +render(@topic) translates to render("topics/topic") +render(topics) translates to render("topics/topic") +render(message.topics) translates to render("topics/topic") ``` On the other hand, some calls need to be changed to make caching work properly. @@ -270,7 +270,7 @@ simply be explicit in a comment, like: Sometimes you need to cache a particular value or query result instead of caching view fragments. Rails' caching mechanism works great for storing __any__ kind of information. -The most efficient way to implement low-level caching is using the `Rails.cache.fetch` method. This method does both reading and writing to the cache. When passed only a single argument, the key is fetched and value from the cache is returned. If a block is passed, the result of the block will be cached to the given key and the result is returned. +The most efficient way to implement low-level caching is using the `Rails.cache.fetch` method. This method does both reading and writing to the cache. When passed only a single argument, the key is fetched and value from the cache is returned. If a block is passed, that block will be executed in the event of a cache miss. The return value of the block will be written to the cache under the given cache key, and that return value will be returned. In case of cache hit, the cached value will be returned without executing the block. Consider the following example. An application has a `Product` model with an instance method that looks up the product’s price on a competing website. The data returned by this method would be perfect for low-level caching: @@ -381,7 +381,7 @@ config.cache_store = :memory_store, { size: 64.megabytes } ``` If you're running multiple Ruby on Rails server processes (which is the case -if you're using mongrel_cluster or Phusion Passenger), then your Rails server +if you're using Phusion Passenger or puma clustered mode), then your Rails server process instances won't be able to share cache data with each other. This cache store is not appropriate for large application deployments. However, it can work well for small, low traffic sites with only a couple of server processes, @@ -512,6 +512,30 @@ class ProductsController < ApplicationController end ``` +Sometimes we want to cache response, for example a static page, that never gets +expired. To achieve this, we can use `http_cache_forever` helper and by doing +so browser and proxies will cache it indefinitely. + +By default cached responses will be private, cached only on the user's web +browser. To allow proxies to cache the response, set `public: true` to indicate +that they can serve the cached response to all users. + +Using this helper, `last_modified` header is set to `Time.new(2011, 1, 1).utc` +and `expires` header is set to a 100 years. + +WARNING: Use this method carefully as browser/proxy won't be able to invalidate +the cached response unless browser cache is forcefully cleared. + +```ruby +class HomeController < ApplicationController + def index + http_cache_forever(public: true) do + render + end + end +end +``` + ### Strong v/s Weak ETags Rails generates weak ETags by default. Weak ETags allow semantically equivalent |