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Diffstat (limited to 'activerecord/lib/active_record/integration.rb')
| -rw-r--r-- | activerecord/lib/active_record/integration.rb | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/integration.rb b/activerecord/lib/active_record/integration.rb new file mode 100644 index 0000000000..90fb10a1f1 --- /dev/null +++ b/activerecord/lib/active_record/integration.rb @@ -0,0 +1,204 @@ +# frozen_string_literal: true + +require "active_support/core_ext/string/filters" + +module ActiveRecord + module Integration + extend ActiveSupport::Concern + + included do + ## + # :singleton-method: + # Indicates the format used to generate the timestamp in the cache key, if + # versioning is off. Accepts any of the symbols in <tt>Time::DATE_FORMATS</tt>. + # + # This is +:usec+, by default. + class_attribute :cache_timestamp_format, instance_writer: false, default: :usec + + ## + # :singleton-method: + # Indicates whether to use a stable #cache_key method that is accompanied + # by a changing version in the #cache_version method. + # + # This is +true+, by default on Rails 5.2 and above. + class_attribute :cache_versioning, instance_writer: false, default: false + end + + # 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 + # <tt>resources :users</tt> 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" + 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 + + # 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 + # Product.find(5).cache_key # => "products/5-20071224150000" (updated_at available) + 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(<<-MSG.squish) + Specifying a timestamp name for #cache_key has been deprecated in favor of + the explicit #cache_version method that can be overwritten. + MSG + + 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 + + # 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). + def cache_version + return unless cache_versioning + + if has_attribute?("updated_at") + timestamp = updated_at_before_type_cast + if can_use_fast_cache_version?(timestamp) + raw_timestamp_to_cache_version(timestamp) + elsif timestamp = updated_at + timestamp.utc.to_s(cache_timestamp_format) + end + else + if self.class.has_attribute?("updated_at") + raise ActiveModel::MissingAttributeError, "missing attribute: updated_at" + end + end + end + + # Returns a cache key along with the version. + def cache_key_with_version + if version = cache_version + "#{cache_key}-#{version}" + else + cache_key + end + end + + module ClassMethods + # Defines your model's +to_param+ method to generate "pretty" URLs + # using +method_name+, which can be any attribute or method that + # responds to +to_s+. + # + # class User < ActiveRecord::Base + # to_param :name + # end + # + # user = User.find_by(name: 'Fancy Pants') + # user.id # => 123 + # user_path(user) # => "/users/123-fancy-pants" + # + # Values longer than 20 characters will be truncated. The value + # is truncated word by word. + # + # user = User.find_by(name: 'David Heinemeier Hansson') + # user.id # => 125 + # user_path(user) # => "/users/125-david-heinemeier" + # + # Because the generated param begins with the record's +id+, it is + # suitable for passing to +find+. In a controller, for example: + # + # params[:id] # => "123-fancy-pants" + # User.find(params[:id]).id # => 123 + def to_param(method_name = nil) + if method_name.nil? + super() + else + define_method :to_param do + if (default = super()) && + (result = send(method_name).to_s).present? && + (param = result.squish.parameterize.truncate(20, separator: /-/, omission: "")).present? + "#{default}-#{param}" + else + default + end + end + end + end + end + + private + # Detects if the value before type cast + # can be used to generate a cache_version. + # + # The fast cache version only works with a + # string value directly from the database. + # + # We also must check if the timestamp format has been changed + # or if the timezone is not set to UTC then + # we cannot apply our transformations correctly. + def can_use_fast_cache_version?(timestamp) + timestamp.is_a?(String) && + cache_timestamp_format == :usec && + default_timezone == :utc && + !updated_at_came_from_user? + end + + # Converts a raw database string to `:usec` + # format. + # + # Example: + # + # timestamp = "2018-10-15 20:02:15.266505" + # raw_timestamp_to_cache_version(timestamp) + # # => "20181015200215266505" + # + # Postgres truncates trailing zeros, + # https://github.com/postgres/postgres/commit/3e1beda2cde3495f41290e1ece5d544525810214 + # to account for this we pad the output with zeros + def raw_timestamp_to_cache_version(timestamp) + key = timestamp.delete("- :.") + if key.length < 20 + key.ljust(20, "0") + else + key + end + end + end +end |