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Instance Public methods
cache_key(*timestamp_names)

Returns a stable cache key that can be used to identify this record.

Product.new.cache_key     # => "products/new"
Product.find(5).cache_key # => "products/5"

If ActiveRecord::Base.cache_versioning is turned off, as it was in Rails 5.1 and earlier, the cache key will also include a version.

Product.cache_versioning = false
Person.find(5).cache_key  # => "people/5-20071224150000" (updated_at available)
# File activerecord/lib/active_record/integration.rb, line 64
    def cache_key(*timestamp_names)
      if new_record?
        "#{model_name.cache_key}/new"
      else
        if cache_version && timestamp_names.none?
          "#{model_name.cache_key}/#{id}"
        else
          timestamp = if timestamp_names.any?
            ActiveSupport::Deprecation.warn("              Specifying a timestamp name for #cache_key has been deprecated in favor of
              the explicit #cache_version method that can be overwritten.
".squish)

            max_updated_column_timestamp(timestamp_names)
          else
            max_updated_column_timestamp
          end

          if timestamp
            timestamp = timestamp.utc.to_s(cache_timestamp_format)
            "#{model_name.cache_key}/#{id}-#{timestamp}"
          else
            "#{model_name.cache_key}/#{id}"
          end
        end
      end
    end
cache_key_with_version()

Returns a cache key along with the version.

# File activerecord/lib/active_record/integration.rb, line 105
def cache_key_with_version
  if version = cache_version
    "#{cache_key}-#{version}"
  else
    cache_key
  end
end
cache_version()

Returns a cache version that can be used together with the cache key to form a recyclable caching scheme. By default, the updated_at column is used for the #cache_version, but this method can be overwritten to return something else.

Note, this method will return nil if ActiveRecord::Base.cache_versioning is set to false (which it is by default until Rails 6.0).

# File activerecord/lib/active_record/integration.rb, line 98
def cache_version
  if cache_versioning && timestamp = try(:updated_at)
    timestamp.utc.to_s(:usec)
  end
end
to_param()

Returns a String, which Action Pack uses for constructing a URL to this object. The default implementation returns this record's id as a String, or nil if this record's unsaved.

For example, suppose that you have a User model, and that you have a resources :users route. Normally, user_path will construct a path with the user object's 'id' in it:

user = User.find_by(name: 'Phusion')
user_path(user)  # => "/users/1"

You can override to_param in your model to make user_path construct a path using the user's name instead of the user's id:

class User < ActiveRecord::Base
  def to_param  # overridden
    name
  end
end

user = User.find_by(name: 'Phusion')
user_path(user)  # => "/users/Phusion"
# File activerecord/lib/active_record/integration.rb, line 49
def to_param
  # We can't use alias_method here, because method 'id' optimizes itself on the fly.
  id && id.to_s # Be sure to stringify the id for routes
end