instance method
update_counters
Ruby on Rails 4.1.16
Since v4.0.13Signature
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 or an Array of ids. -
counters- A Hash 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 = COALESCE(comment_count, 0) - 1, # action_count = COALESCE(action_count, 0) + 1 # WHERE id = 5 # For the Posts with id of 10 and 15, increment the comment_count by 1 Post.update_counters [10, 15], comment_count: 1 # Executes the following SQL: # UPDATE posts # SET comment_count = COALESCE(comment_count, 0) + 1 # WHERE id IN (10, 15)
Parameters
-
idreq -
countersreq
Source
# File activerecord/lib/active_record/counter_cache.rb, line 72
def update_counters(id, counters)
updates = counters.map do |counter_name, value|
operator = value < 0 ? '-' : '+'
quoted_column = connection.quote_column_name(counter_name)
"#{quoted_column} = COALESCE(#{quoted_column}, 0) #{operator} #{value.abs}"
end
unscoped.where(primary_key => id).update_all updates.join(', ')
end
Defined in activerecord/lib/active_record/counter_cache.rb line 72
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Defined in ActiveRecord::CounterCache::ClassMethods