Class: CounterCulture::Counter

Inherits:
Object
  • Object
show all
Defined in:
lib/counter_culture/counter.rb

Constant Summary collapse

CONFIG_OPTIONS = 
[ :column_names, :counter_cache_name, :delta_column, :foreign_key_values, :touch, :delta_magnitude, :execute_after_commit ]
ACTIVE_RECORD_VERSION = 
Gem.loaded_specs["activerecord"].version

Instance Method Summary collapse

Constructor Details

#initialize(model, relation, options) ⇒ Counter 



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# File 'lib/counter_culture/counter.rb', line 10

def initialize(model, relation, options)
  @model = model
  @relation = relation.is_a?(Enumerable) ? relation : [relation]

  @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)
  @execute_after_commit = options.fetch(:execute_after_commit, false)

  if @execute_after_commit
    begin
      require 'after_commit_action'
    rescue LoadError
      fail(LoadError.new(
        "You need to include the `after_commit_action` gem in your "\
        "gem dependencies to use the execute_after_commit option"))
    end
    model.include(AfterCommitAction)
  end
end

Instance Method Details

#attribute_changed?(obj, attr) ⇒ Boolean 



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# File 'lib/counter_culture/counter.rb', line 303

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

#change_counter_cache(obj, options) ⇒ Object

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



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# File 'lib/counter_culture/counter.rb', line 46

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
    return if delta_magnitude.zero?

    # increment or decrement?
    operator = options[:increment] ? '+' : '-'

    klass = relation_klass(relation, source: obj, was: options[:was])

    # MySQL throws an ambiguous column error if any joins are present and we don't include the
    # table name. We isolate this change to MySQL because sqlite has the opposite behavior and
    # throws an exception if the table name is present after UPDATE.
    quoted_column = WithConnection.new(klass).call do |connection|
      if connection.adapter_name == 'Mysql2'
        "#{klass.quoted_table_name}.#{connection.quote_column_name(change_counter_column)}"
      else
        "#{connection.quote_column_name(change_counter_column)}"
      end
    end

    column_type = klass.type_for_attribute(change_counter_column).type

    # we don't use Rails' update_counters because we support changing the timestamp
    updates = []

    # this will update the actual counter
    updates << if column_type == :money
      assemble_money_counter_update(klass, id_to_change, quoted_column, operator, delta_magnitude)
    else
      assemble_counter_update(klass, id_to_change, quoted_column, operator, delta_magnitude)
    end

    # and this will update the timestamp, if so desired
    if touch
      current_time = klass.send(:current_time_from_proper_timezone)
      timestamp_columns = klass.send(:timestamp_attributes_for_update_in_model)
      if touch != true
        # starting in Rails 6 this is frozen
        timestamp_columns = timestamp_columns.dup
        timestamp_columns << touch
      end
      timestamp_columns.each do |timestamp_column|
        updates << assemble_timestamp_update(
          klass,
          id_to_change,
          timestamp_column,
          -> { klass.send(:current_time_from_proper_timezone).to_formatted_s(:db) }
        )
      end
    end

    primary_key = relation_primary_key(relation, source: obj, was: options[:was])

    if foreign_key_values && id_to_change.is_a?(Enumerable) && id_to_change.count > 1 &&
        Array.wrap(primary_key).count == 1
      # To keep this feature backwards compatible, we need to accommodate a case where
      # `foreign_key_values` returns an array, but we're _not_ using composite primary
      # keys. In that case, we need to wrap the `id_to_change` in one more array to keep
      # it compatible with the `.zip` call in `primary_key_conditions`.
      id_to_change = [id_to_change]
    end

    if Thread.current[:aggregate_counter_updates]
      Thread.current[:primary_key_map][klass] ||= primary_key
    end

    if @with_papertrail
      conditions = primary_key_conditions(primary_key, id_to_change)
      instance = klass.where(conditions).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

          execute_now_or_after_commit(obj) do
            instance.paper_trail.save_with_version(validate: false)
          end
        else
          execute_now_or_after_commit(obj) do
            instance.paper_trail.touch_with_version
          end
        end
      end
    end

    unless Thread.current[:aggregate_counter_updates]
      execute_now_or_after_commit(obj) do
        conditions = primary_key_conditions(primary_key, id_to_change)
        klass.where(conditions).update_all updates.join(', ')
        # Determine if we should update the in-memory counter on the associated object.
        # When updating the old counter (was: true), we need to carefully consider two scenarios:
        # 1) The belongs_to relation changed (e.g., moving a child from parent A to parent B):
        #    In this case, obj.association now points to parent B, but we're decrementing parent A's
        #    counter. We should NOT update the in-memory counter because it would incorrectly
        #    modify parent B's cached value.
        # 2) A conditional counter's condition changed (e.g., condition: true → false):
        #    In this case, obj.association still points to the same parent, but the counter column
        #    name changed (e.g., from 'conditional_count' to nil). We SHOULD update the in-memory
        #    counter so the parent object reflects the decremented value without requiring a reload.
        # We distinguish these cases by comparing foreign keys: if the current and previous foreign
        # keys are identical, we're in scenario 2 and should update the in-memory counter.
        should_update_counter = if options[:was]
          current_fk = foreign_key_value(obj, relation, false)
          previous_fk = foreign_key_value(obj, relation, true)
          current_fk == previous_fk && current_fk.present?
        else
          true
        end

        if should_update_counter
          assign_to_associated_object(obj, relation, change_counter_column, operator, delta_magnitude)
        end
      end
    end
  end
end

#counter_cache_name_for(obj) ⇒ Object

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



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# File 'lib/counter_culture/counter.rb', line 196

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

#counter_delta_magnitude_for(obj) ⇒ Object

Gets the delta magnitude of the counter cache for a specific object

obj: object to calculate the counter cache name for



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# File 'lib/counter_culture/counter.rb', line 184

def counter_delta_magnitude_for(obj)
  if delta_magnitude.is_a?(Proc)
    delta_magnitude.call(obj)
  else
    delta_magnitude
  end
end

#execute_now_or_after_commit(obj, &block) ⇒ Object 



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# File 'lib/counter_culture/counter.rb', line 383

def execute_now_or_after_commit(obj, &block)
  execute_after_commit = @execute_after_commit.is_a?(Proc) ? @execute_after_commit.call : @execute_after_commit

  if execute_after_commit
    obj.execute_after_commit(&block)
  else
    block.call
  end
end

#first_level_relation_changed?(instance) ⇒ Boolean 



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# File 'lib/counter_culture/counter.rb', line 295

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

#first_level_relation_foreign_key ⇒ Object

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



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# File 'lib/counter_culture/counter.rb', line 356

def first_level_relation_foreign_key
  first_relation = relation.first if relation.is_a?(Enumerable)
  relation_reflect(first_relation).foreign_key
end

#first_level_relation_foreign_type ⇒ Object 



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# File 'lib/counter_culture/counter.rb', line 361

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

#foreign_key_value(obj, relation, was = false) ⇒ Object

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



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# File 'lib/counter_culture/counter.rb', line 219

def foreign_key_value(obj, relation, was = false)
  original_relation = relation
  relation = relation.is_a?(Enumerable) ? relation.dup : [relation]

  value = 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
      primary_key = relation_primary_key(first, source: obj, was: was)
      conditions = primary_key_conditions(primary_key, foreign_key_value)
      klass.where(conditions).first
    end
  else
    obj
  end
  while !value.nil? && relation.size > 0
    value = value.send(relation.shift)
  end

  primary_key = relation_primary_key(original_relation, source: obj, was: was)
  Array.wrap(primary_key).map { |pk| value.try(pk&.to_sym) }.compact.presence
end

#full_primary_key(klass) ⇒ Object

the string to pass to order() in order to sort by primary key



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# File 'lib/counter_culture/counter.rb', line 208

def full_primary_key(klass)
  Array.wrap(klass.quoted_primary_key).map { |pk| "#{klass.quoted_table_name}.#{pk}" }.join(', ')
end

#polymorphic? ⇒ Boolean 



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# File 'lib/counter_culture/counter.rb', line 311

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

#previous_model(obj) ⇒ Object 



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# File 'lib/counter_culture/counter.rb', line 367

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|
    next unless obj.has_attribute?(key.to_s)

    old_value = ACTIVE_RECORD_VERSION >= Gem::Version.new("5.1.0") ? value.first : value
    # We set old values straight to AR @attributes variable to avoid
    # write_attribute callbacks from other gems (e.g. ArTransactionChanges)
    prev.instance_variable_get(:@attributes).write_from_user(key, old_value)
  end

  prev
end

#relation_foreign_key(relation) ⇒ Object

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



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# File 'lib/counter_culture/counter.rb', line 323

def relation_foreign_key(relation)
  relation_reflect(relation).foreign_key
end

#relation_klass(relation, source: nil, was: false) ⇒ Object

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



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# File 'lib/counter_culture/counter.rb', line 277

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

#relation_primary_key(relation, source: nil, was: false) ⇒ Object

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: 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



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# File 'lib/counter_culture/counter.rb', line 336

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 reflect.options[:primary_key] if reflect.options.key?(:primary_key)
    return relation_klass(relation, source: source, was: was).try(:primary_key)
  end

  reflect.association_primary_key(klass)
end

#relation_reflect(relation) ⇒ Object

gets the reflect object on the given relation

relation: a symbol or array of symbols; specifies the relation

that has the counter cache column



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# File 'lib/counter_culture/counter.rb', line 247

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