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counter.rb
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counter.rb
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module CounterCulture
class Counter
CONFIG_OPTIONS = [ :column_names, :counter_cache_name, :delta_column, :foreign_key_values, :touch, :delta_magnitude]
ACTIVE_RECORD_VERSION = Gem.loaded_specs["activerecord"].version
attr_reader :model, :relation, *CONFIG_OPTIONS
def initialize(model, relation, options)
@model = model
@relation = relation.is_a?(Enumerable) ? relation : [relation]
if options.fetch(:execute_after_commit, false)
fail("execute_after_commit was removed; updates now run within the transaction")
end
@counter_cache_name = options.fetch(:column_name, "#{model.name.demodulize.tableize}_count")
@column_names = options[:column_names]
@delta_column = options[:delta_column]
@foreign_key_values = options[:foreign_key_values]
@touch = options.fetch(:touch, false)
@delta_magnitude = options[:delta_magnitude] || 1
@with_papertrail = options.fetch(:with_papertrail, false)
end
# increments or decrements a counter cache
#
# options:
# :increment => true to increment, false to decrement
# :relation => which relation to increment the count on,
# :counter_cache_name => the column name of the counter cache
# :counter_column => overrides :counter_cache_name
# :delta_column => override the default count delta (1) with the value of this column in the counted record
# :was => whether to get the current value or the old value of the
# first part of the relation
# :with_papertrail => update the column via Papertrail touch_with_version method
def change_counter_cache(obj, options)
change_counter_column = options.fetch(:counter_column) { counter_cache_name_for(obj) }
# default to the current foreign key value
id_to_change = foreign_key_value(obj, relation, options[:was])
# allow overwriting of foreign key value by the caller
id_to_change = foreign_key_values.call(id_to_change) if foreign_key_values
if id_to_change && change_counter_column
delta_magnitude = if delta_column
(options[:was] ? attribute_was(obj, delta_column) : obj.public_send(delta_column)) || 0
else
counter_delta_magnitude_for(obj)
end
# increment or decrement?
operator = options[:increment] ? '+' : '-'
# we don't use Rails' update_counters because we support changing the timestamp
quoted_column = model.connection.quote_column_name(change_counter_column)
updates = []
# this updates the actual counter
updates << "#{quoted_column} = COALESCE(#{quoted_column}, 0) #{operator} #{delta_magnitude}"
# and here we update the timestamp, if so desired
if touch
current_time = obj.send(:current_time_from_proper_timezone)
timestamp_columns = obj.send(:timestamp_attributes_for_update_in_model)
timestamp_columns << touch if touch != true
timestamp_columns.each do |timestamp_column|
updates << "#{timestamp_column} = '#{current_time.to_formatted_s(:db)}'"
end
end
klass = relation_klass(relation, source: obj, was: options[:was])
primary_key = relation_primary_key(relation, source: obj, was: options[:was])
if @with_papertrail
instance = klass.where(primary_key => id_to_change).first
if instance
if instance.paper_trail.respond_to?(:save_with_version)
# touch_with_version is deprecated starting in PaperTrail 9.0.0
current_time = obj.send(:current_time_from_proper_timezone)
timestamp_columns = obj.send(:timestamp_attributes_for_update_in_model)
timestamp_columns.each do |timestamp_column|
instance.send("#{timestamp_column}=", current_time)
end
instance.paper_trail.save_with_version(validate: false)
else
instance.paper_trail.touch_with_version
end
end
end
klass.where(primary_key => id_to_change).update_all updates.join(', ')
end
end
# Gets the delta magnitude of the counter cache for a specific object
#
# obj: object to calculate the counter cache name for
def counter_delta_magnitude_for(obj)
if delta_magnitude.is_a?(Proc)
delta_magnitude.call(obj)
else
delta_magnitude
end
end
# Gets the name of the counter cache for a specific object
#
# obj: object to calculate the counter cache name for
# cache_name_finder: object used to calculate the cache name
def counter_cache_name_for(obj)
# figure out what the column name is
if counter_cache_name.is_a?(Proc)
# dynamic column name -- call the Proc
counter_cache_name.call(obj)
else
# static column name
counter_cache_name
end
end
# the string to pass to order() in order to sort by primary key
def full_primary_key(klass)
"#{klass.quoted_table_name}.#{klass.quoted_primary_key}"
end
# gets the value of the foreign key on the given relation
#
# relation: a symbol or array of symbols; specifies the relation
# that has the counter cache column
# was: whether to get the current or past value from ActiveRecord;
# pass true to get the past value, false or nothing to get the
# current value
def foreign_key_value(obj, relation, was = false)
relation = relation.is_a?(Enumerable) ? relation.dup : [relation]
first_relation = relation.first
if was
first = relation.shift
foreign_key_value = attribute_was(obj, relation_foreign_key(first))
klass = relation_klass(first, source: obj, was: was)
if foreign_key_value
value = klass.where(
"#{klass.table_name}.#{relation_primary_key(first, source: obj, was: was)} = ?",
foreign_key_value).first
end
else
value = obj
end
while !value.nil? && relation.size > 0
value = value.send(relation.shift)
end
return value.try(relation_primary_key(first_relation, source: obj, was: was).try(:to_sym))
end
# gets the reflect object on the given relation
#
# relation: a symbol or array of symbols; specifies the relation
# that has the counter cache column
def relation_reflect(relation)
relation = relation.is_a?(Enumerable) ? relation.dup : [relation]
# go from one relation to the next until we hit the last reflect object
klass = model
while relation.size > 0
cur_relation = relation.shift
reflect = klass.reflect_on_association(cur_relation)
raise "No relation #{cur_relation} on #{klass.name}" if reflect.nil?
if relation.size > 0
# not necessary to do this at the last link because we won't use
# klass again. not calling this avoids the following causing an
# exception in the now-supported one-level polymorphic counter cache
klass = reflect.klass
end
end
return reflect
end
# gets the class of the given relation
#
# relation: a symbol or array of symbols; specifies the relation
# that has the counter cache column
# source [optional]: the source object,
# only needed for polymorphic associations,
# probably only works with a single relation (symbol, or array of 1 symbol)
# was: boolean
# we're actually looking for the old value -- only can change for polymorphic relations
def relation_klass(relation, source: nil, was: false)
reflect = relation_reflect(relation)
if reflect.options.key?(:polymorphic)
raise "Can't work out relation's class without being passed object (relation: #{relation}, reflect: #{reflect})" if source.nil?
raise "Can't work out polymorhpic relation's class with multiple relations yet" unless (relation.is_a?(Symbol) || relation.length == 1)
# this is the column that stores the polymorphic type, aka the class name
type_column = reflect.foreign_type.to_sym
# so now turn that into the class that we're looking for here
if was
attribute_was(source, type_column).try(:constantize)
else
source.public_send(type_column).try(:constantize)
end
else
reflect.klass
end
end
def first_level_relation_changed?(instance)
return true if attribute_changed?(instance, first_level_relation_foreign_key)
if polymorphic?
return true if attribute_changed?(instance, first_level_relation_foreign_type)
end
false
end
def attribute_changed?(obj, attr)
if ACTIVE_RECORD_VERSION >= Gem::Version.new("5.1.0")
obj.saved_changes[attr].present?
else
obj.send(:attribute_changed?, attr)
end
end
def polymorphic?
is_polymorphic = relation_reflect(relation).options.key?(:polymorphic)
if is_polymorphic && !(relation.is_a?(Symbol) || relation.length == 1)
raise "Polymorphic associations only supported with one level"
end
return is_polymorphic
end
# gets the foreign key name of the given relation
#
# relation: a symbol or array of symbols; specifies the relation
# that has the counter cache column
def relation_foreign_key(relation)
relation_reflect(relation).foreign_key
end
# gets the primary key name of the given relation
#
# relation: a symbol or array of symbols; specifies the relation
# that has the counter cache column
# source[optional]: the model instance that the relationship is linked from,
# only needed for polymorphic associations,
# probably only works with a single relation (symbol, or array of 1 symbol)
# was: boolean
# we're actually looking for the old value -- only can change for polymorphic relations
def relation_primary_key(relation, source: nil, was: false)
reflect = relation_reflect(relation)
klass = nil
if reflect.options.key?(:polymorphic)
raise "can't handle multiple keys with polymorphic associations" unless (relation.is_a?(Symbol) || relation.length == 1)
raise "must specify source for polymorphic associations..." unless source
return relation_klass(relation, source: source, was: was).try(:primary_key)
end
reflect.association_primary_key(klass)
end
# gets the foreign key name of the relation. will look at the first
# level only -- i.e., if passed an array will consider only its
# first element
#
# relation: a symbol or array of symbols; specifies the relation
# that has the counter cache column
def first_level_relation_foreign_key
first_relation = relation.first if relation.is_a?(Enumerable)
relation_reflect(first_relation).foreign_key
end
def first_level_relation_foreign_type
return nil unless polymorphic?
first_relation = relation.first if relation.is_a?(Enumerable)
relation_reflect(first_relation).foreign_type
end
def previous_model(obj)
prev = obj.dup
changes_method = ACTIVE_RECORD_VERSION >= Gem::Version.new("5.1.0") ? :saved_changes : :changed_attributes
obj.public_send(changes_method).each do |key, value|
old_value = ACTIVE_RECORD_VERSION >= Gem::Version.new("5.1.0") ? value.first : value
prev.public_send("#{key}=", old_value)
end
prev
end
private
def attribute_was(obj, attr)
changes_method =
if ACTIVE_RECORD_VERSION >= Gem::Version.new("5.1.0")
"_before_last_save"
else
"_was"
end
obj.public_send("#{attr}#{changes_method}")
end
end
end