Class | ActiveSupport::Cache::Store
In: | lib/active_support/cache.rb
Parent: | Object

An abstract cache store class. There are multiple cache store implementations, each having its own additional features. See the classes under the ActiveSupport::Cache module, e.g. ActiveSupport::Cache::MemCacheStore. MemCacheStore is currently the most popular cache store for large production websites.

ActiveSupport::Cache::Store is meant for caching strings. Some cache store implementations, like MemoryStore, are able to cache arbitrary Ruby objects, but don‘t count on every cache store to be able to do that.

      cache = ActiveSupport::Cache::MemoryStore.new

      cache.read("city")   # => nil
      cache.write("city", "Duckburgh")
      cache.read("city")   # => "Duckburgh"

### Methods

decrement delete delete_matched exist? fetch increment read silence! write

### Public Instance methods

decrement(key, amount = 1)
delete(key, options = nil)
delete_matched(matcher, options = nil)
exist?(key, options = nil)
fetch(key, options = {}) {|| ...}

Fetches data from the cache, using the given key. If there is data in the cache with the given key, then that data is returned.

If there is no such data in the cache (a cache miss occurred), then then nil will be returned. However, if a block has been passed, then that block will be run 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.

      cache.write("today", "Monday")
      cache.fetch("today")  # => "Monday"

      cache.fetch("city")   # => nil
      cache.fetch("city") do
        "Duckburgh"
      end
      cache.fetch("city")   # => "Duckburgh"

You may also specify additional options via the `options` argument. Setting `:force => true` will force a cache miss:

      cache.write("today", "Monday")
      cache.fetch("today", :force => true)  # => nil

Other options will be handled by the specific cache store implementation. Internally, fetch calls read, and calls write on a cache miss. `options` will be passed to the read and write calls.

For example, MemCacheStore‘s write method supports the +:expires_in+ option, which tells the memcached server to automatically expire the cache item after a certain period. We can use this option with fetch too:

      cache = ActiveSupport::Cache::MemCacheStore.new
      cache.fetch("foo", :force => true, :expires_in => 5.seconds) do
        "bar"
      end
      cache.fetch("foo")  # => "bar"
      sleep(6)
      cache.fetch("foo")  # => nil

increment(key, amount = 1)
read(key, options = nil)

Fetches data from the cache, using the given key. If there is data in the cache with the given key, then that data is returned. Otherwise, nil is returned.

You may also specify additional options via the `options` argument. The specific cache store implementation will decide what to do with `options`.

silence!()
write(key, value, options = nil)

Writes the given value to the cache, with the given key.

You may also specify additional options via the `options` argument. The specific cache store implementation will decide what to do with `options`.

For example, MemCacheStore supports the +:expires_in+ option, which tells the memcached server to automatically expire the cache item after a certain period:

      cache = ActiveSupport::Cache::MemCacheStore.new
      cache.write("foo", "bar", :expires_in => 5.seconds)
      cache.read("foo")  # => "bar"
      sleep(6)
      cache.read("foo")  # => nil

[Validate]