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 ]

Instance Method Summary collapse

Constructor Details

#initialize(model, relation, options) ⇒ Counter

Returns a new instance of Counter.



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# File 'lib/counter_culture/counter.rb', line 7

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

  @counter_cache_name = options.fetch(:column_name, "#{model.name.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
  @execute_after_commit = options.fetch(:execute_after_commit, false)
end

Instance Method Details

#attribute_changed?(obj, attr) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/counter_culture/counter.rb', line 191

def attribute_changed?(obj, attr)
  if Rails.version >= "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
:execute_after_commit => execute the column update outside of the transaction to avoid deadlocks



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# File 'lib/counter_culture/counter.rb', line 31

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
    execute_change_counter_cache(obj, options) do
      # 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])
      klass.where(primary_key => id_to_change).update_all updates.join(', ')
    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 87

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 75

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

#first_level_relation_changed?(instance) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/counter_culture/counter.rb', line 183

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 241

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 246

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 110

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

#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 99

def full_primary_key(klass)
  "#{klass.quoted_table_name}.#{klass.quoted_primary_key}"
end

#polymorphic? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/counter_culture/counter.rb', line 199

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 252

def previous_model(obj)
  prev = obj.dup

  changes_method = Rails.version >= "5.1.0" ? :saved_changes : :changed_attributes
  obj.public_send(changes_method).each do |key, value|
    old_value = Rails.version >= "5.1.0" ? value.first : value
    prev.public_send("#{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 211

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 165

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 224

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

#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 135

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