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

#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
                        delta_attr_name = options[:was] ? "#{delta_column}_was" : delta_column
                        obj.send(delta_attr_name) || 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)
      klass.where(relation_primary_key(relation) => 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_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 176

def first_level_relation_foreign_key
  first_relation = relation.first if relation.is_a?(Enumerable)
  relation_reflect(first_relation).foreign_key
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 = obj.send("#{relation_foreign_key(first)}_was")
    klass = relation_klass(first)
    value = klass.where("#{klass.table_name}.#{relation_primary_key(first)} = ?", foreign_key_value).first if foreign_key_value
  else
    value = obj
  end
  while !value.nil? && relation.size > 0
    value = value.send(relation.shift)
  end
  return value.try(relation_primary_key(first_relation).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

#previous_model(obj) ⇒ Object 



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# File 'lib/counter_culture/counter.rb', line 181

def previous_model(obj)
  prev = obj.dup

  obj.changed_attributes.each do |key, value|
    prev.send("#{key}=", 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 158

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

#relation_klass(relation) ⇒ Object

gets the class 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 150

def relation_klass(relation)
  relation_reflect(relation).klass
end

#relation_primary_key(relation) ⇒ 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



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# File 'lib/counter_culture/counter.rb', line 166

def relation_primary_key(relation)
  relation_reflect(relation).association_primary_key
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 131

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?
    klass = reflect.klass
  end

  return reflect
end