Module: Statistics::HasStats

Defined in:
lib/statistics.rb

Overview

This extension provides the ability to define statistics for reporting purposes

Instance Method Summary collapse

Instance Method Details

#define_calculated_statistic(name, &block) ⇒ Object

Defines a statistic using a block that has access to all other defined statistics

EXAMPLE: class MockModel < ActiveRecord::Base

define_statistic "Basic Count", :count => :all
define_statistic "Basic Sum", :sum => :all, :column_name => 'amount'
define_calculated_statistic "Total Profit"
  defined_stats('Basic Sum') * defined_stats('Basic Count')
end



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# File 'lib/statistics.rb', line 105

def define_calculated_statistic(name, &block)
  method_name = name.to_s.gsub(" ", "").underscore + "_stat"

  @statistics ||= {}
  @statistics[name] = method_name

  (class<<self; self; end).instance_eval do
    define_method(method_name) do |filters|
      @filters = filters
      yield
    end
  end
end

#define_statistic(name, options) ⇒ Object

OPTIONS:

  • average, count, sum, maximum, minimum - Only one of these keys is passed, which one depends on the type of operation. The value is an array of named scopes to scope the operation by (:all should be used if no scopes are to be applied)

  • column_name - The SQL column to perform the operation on (default: id)

  • filter_on - A hash with keys that represent filters. The with values in the has are rules on how to generate the query for the correspond filter.

  • cached_for - A duration for how long to cache this specific statistic

    Additional options can also be passed in that would normally be passed to an ActiveRecord calculate call, like conditions, joins, etc

EXAMPLE:

class MockModel < ActiveRecord::Base

  named_scope :my_scope, :conditions => 'value > 5'

  define_statistic "Basic Count", :count => :all
  define_statistic "Basic Sum", :sum => :all, :column_name => 'amount'
  define_statistic "Chained Scope Count", :count => [:all, :my_scope]
  define_statistic "Default Filter", :count => :all
  define_statistic "Custom Filter", :count => :all, :filter_on => { :channel => 'channel = ?', :start_date => 'DATE(created_at) > ?' }
  define_statistic "Cached", :count => :all, :filter_on => { :channel => 'channel = ?', :blah => 'blah = ?' }, :cache_for => 1.second
end



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# File 'lib/statistics.rb', line 45

def define_statistic(name, options)
  method_name = name.to_s.gsub(" ", "").underscore + "_stat"

  @statistics ||= {}
  @filter_all_on ||= ActiveRecord::Base.instance_eval { @filter_all_on }
  @statistics[name] = method_name

  options = { :column_name => :id }.merge(options)

  calculation = options.keys.find {|opt| Statistics::supported_calculations.include?(opt)}
  calculation ||= :count

  # We must use the metaclass here to metaprogrammatically define a class method
  (class<<self; self; end).instance_eval do
    define_method(method_name) do |filters|
      # check the cache before running a query for the stat
      cached_val = Rails.cache.read("#{self.name}#{method_name}#{filters}") if options[:cache_for]
      return cached_val unless cached_val.nil?

      scoped_options = Marshal.load(Marshal.dump(options))

      filters.each do |key, value|
        unless value.nil?
          sql = ((@filter_all_on || {}).merge(scoped_options[:filter_on] || {}))[key].gsub("?", "'#{value}'")
          sql = sql.gsub("%t", "#{table_name}")
          sql_frag = send(:sanitize_sql_for_conditions, sql)
          case
            when sql_frag.nil? then nil
            when scoped_options[:conditions].nil? then scoped_options[:conditions] = sql_frag
            when scoped_options[:conditions].is_a?(Array) then scoped_options[:conditions][0].concat(" AND #{sql_frag}")
            when scoped_options[:conditions].is_a?(String) then scoped_options[:conditions].concat(" AND #{sql_frag}")
          end
        end
      end if filters.is_a?(Hash)

      base = self
      # chain named scopes
      scopes = Array(scoped_options[calculation])
      scopes.each do |scope|
        base = base.send(scope)
      end if scopes != [:all]
      stat_value = base.send(calculation, scoped_options[:column_name], sql_options(scoped_options))

      # cache stat value
      Rails.cache.write("#{self.name}#{method_name}#{filters}", stat_value, :expires_in => options[:cache_for]) if options[:cache_for]

      stat_value
    end
  end
end

#filter_all_stats_on(name, cond) ⇒ Object

to keep things DRY anything that all statistics need to be filterable by can be defined seperatly using this method

EXAMPLE:

class MockModel < ActiveRecord::Base

define_statistic "Basic Count", :count => :all
define_statistic "Basic Sum", :sum => :all, :column_name => 'amount'

filter_all_stats_on(:user_id, "user_id = ?")

end



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# File 'lib/statistics.rb', line 158

def filter_all_stats_on(name, cond)
  @filter_all_on ||= {}
  @filter_all_on[name] = cond
end

#get_stat(stat_name, filters = {}) ⇒ Object

returns a single statistic based on the stat_name paramater passed in and similarly to the statistics method, it also can take filters.

EXAMPLE: MockModel.get_stat(‘Basic Count’) MockModel.get_stat(‘Basic Count’, :user_type => ‘registered’, :user_status => ‘active’)



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# File 'lib/statistics.rb', line 143

def get_stat(stat_name, filters = {})
  send(@statistics[stat_name], filters) if @statistics[stat_name]
end

#statistics(filters = {}, except = nil) ⇒ Object

Calculates all the statistics defined for this AR class and returns a hash with the values. There is an optional parameter that is a hash of all values you want to filter by.

EXAMPLE: MockModel.statistics MockModel.statistics(:user_type => ‘registered’, :user_status => ‘active’)



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# File 'lib/statistics.rb', line 130

def statistics(filters = {}, except = nil)
  (@statistics || {}).inject({}) do |stats_hash, stat|
    stats_hash[stat.first] = send(stat.last, filters) if stat.last != except
    stats_hash
  end
end

#statistics_keys ⇒ Object

returns an array containing the names/keys of all defined statistics



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# File 'lib/statistics.rb', line 120

def statistics_keys
  @statistics.keys
end