instance method
cache_key
Ruby on Rails 5.2.8.1
Since v5.2.8.1Signature
cache_key(timestamp_column = :updated_at)Returns a cache key that can be used to identify the records fetched by this query. The cache key is built with a fingerprint of the sql query, the number of records matched by the query and a timestamp of the last updated record. When a new record comes to match the query, or any of the existing records is updated or deleted, the cache key changes.
Product.where("name like ?", "%Cosmic Encounter%").cache_key
# => "products/query-1850ab3d302391b85b8693e941286659-1-20150714212553907087000"
If the collection is loaded, the method will iterate through the records to generate the timestamp, otherwise it will trigger one SQL query like:
SELECT COUNT(*), MAX("products"."updated_at") FROM "products" WHERE (name like '%Cosmic Encounter%')You can also pass a custom timestamp column to fetch the timestamp of the last updated record.
Product.where("name like ?", "%Game%").cache_key(:last_reviewed_at)
You can customize the strategy to generate the key on a per model basis overriding ActiveRecord::Base#collection_cache_key.
Parameters
-
timestamp_columnopt = :updated_at
Source
# File activerecord/lib/active_record/relation.rb, line 265
def cache_key(timestamp_column = :updated_at)
@cache_keys ||= {}
@cache_keys[timestamp_column] ||= @klass.collection_cache_key(self, timestamp_column)
end
Defined in activerecord/lib/active_record/relation.rb line 265
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Defined in ActiveRecord::Relation