self.update_counters(id, counters) — ActiveRecord::Base

self.update_counters(id, counters)

A generic “counter updater” implementation, intended primarily to be used by increment_counter and decrement_counter, but which may also be useful on its own. It simply does a direct SQL update for the record with the given ID, altering the given hash of counters by the amount given by the corresponding value:

Parameters

id - The id of the object you wish to update a counter on.
counters - An Array of Hashes containing the names of the fields to update as keys and the amount to update the field by as values.

Examples

# For the Post with id of 5, decrement the comment_count by 1, and
# increment the action_count by 1
Post.update_counters 5, :comment_count => -1, :action_count => 1
# Executes the following SQL:
# UPDATE posts
#    SET comment_count = comment_count - 1,
#        action_count = action_count + 1
#  WHERE id = 5

Parameters

id req
counters req

Source

# File activerecord/lib/active_record/base.rb, line 903
      def update_counters(id, counters)
        updates = counters.inject([]) { |list, (counter_name, increment)|
          sign = increment < 0 ? "-" : "+"
          list << "#{connection.quote_column_name(counter_name)} = COALESCE(#{connection.quote_column_name(counter_name)}, 0) #{sign} #{increment.abs}"
        }.join(", ")
        update_all(updates, "#{connection.quote_column_name(primary_key)} = #{quote_value(id)}")
      end

Defined in activerecord/lib/active_record/base.rb line 903 · View on GitHub · Improve this page · Find usages on GitHub

Defined in ActiveRecord::Base

Signature

Parameters

Examples

Parameters