如何在 Ruby on Rails 上列出内存缓存存储中的键？
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How can I list the keys in the in-memory cache store on Ruby on Rails?
提问by Nerian
I am using Rails 3.
我正在使用 Rails 3。
How can I list the keys in the in-memory cache store on Ruby on Rails?
如何在 Ruby on Rails 上列出内存缓存存储中的键？
采纳答案by Jordan Running
ActiveSupport::Cache::MemoryStoredoesn't provide a way to access the store's keys directly (and neither does its parent class ActiveSupport::Cache::Store).
ActiveSupport::Cache::MemoryStore不提供直接访问存储键的方法（其父类ActiveSupport::Cache::Store也不提供）。
Internally MemoryStore keeps everything in a Hash called @data, however, so you could monkey-patch or subclass it to get the keys, e.g.:
@data但是，在内部 MemoryStore 将所有内容保存在名为 的 Hash中，因此您可以对它进行猴子补丁或子类化以获取密钥，例如：
class InspectableMemoryStore < ActiveSupport::Cache::MemoryStore
def keys
@data.keys
end
end
ActionController::Base.cache_store = InspectableMemoryStore.new
Rails.cache.keys # => [ "foo", ... ]
This comes with the usual caveat, however: MemoryStore's internal implementation may change at any time and @datamay disappear or be changed to something that doesn't respond_to? :keys. A smarter implementation might be to override the writeand deletemethods (since, as part of the public API, they're unlikely to change unexpectedly) to keep your own list of keys, e.g.:
然而，这带有通常的警告：MemoryStore 的内部实现可能随时更改，并且@data可能会消失或更改为不存在的内容respond_to? :keys。更聪明的实现可能是覆盖write和delete方法（因为作为公共 API 的一部分，它们不太可能意外更改）以保留您自己的密钥列表，例如：
class InspectableMemoryStore < ActiveSupport::Cache::MemoryStore
def write *args
super
@inspectable_keys[ args[0] ] = true
end
def delete *args
super
@inspectable_keys.delete args[0]
end
def keys
@inspectable_keys.keys
end
end
This is a very naive implementation, and of course keeping the keys in an additional structure takes up some memory, but you get the gist.
这是一个非常幼稚的实现，当然，将键保存在一个额外的结构中会占用一些内存，但你明白了要点。
回答by Micha? Dulat
Rails.cache.instance_variable_get(:@data).keys
回答by Maragues
If you don't need to access the keys dynamically, an easier approach is locating the directory where the cache is stored. A file is created for each entry.
如果您不需要动态访问密钥，更简单的方法是定位存储缓存的目录。为每个条目创建一个文件。
In my case this was at "APP_ROOT/tmp/cache", but you can easily locate it by going to rails console and typing
在我的情况下，这是在“APP_ROOT/tmp/cache”，但您可以通过转到 rails 控制台并键入轻松找到它
1.8.7 :030 > Rails.cache.clear
=> ["path_to_rails_app/tmp/cache/6D5"]
回答by TorvaldsDB
Fetch all keys:
获取所有密钥：
Rails.cache.data.keys
Read the specific key
读取特定键
Rails.cache.read("cache_key")
Delete one key from keys:
从键中删除一个键：
Rails.cache.delete("cache_key")
Flush out the keys
冲出钥匙
Rails.cache.clear
