search_term.rb
2.43 KB
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class SearchTerm < ActiveRecord::Base
validates_presence_of :term, :context
validates_uniqueness_of :term, :scope => [:context_id, :context_type, :asset]
belongs_to :context, :polymorphic => true
has_many :occurrences, :class_name => 'SearchTermOccurrence'
attr_accessible :term, :context, :asset
def self.calculate_scores
os = occurrences_scores
find_each { |search_term| search_term.calculate_score(os) }
end
def self.find_or_create(term, context, asset='all')
context.search_terms.where(:term => term, :asset => asset).first || context.search_terms.create!(:term => term, :asset=> asset)
end
# Fast way of getting the occurrences score for each search_term. Ugly but fast!
#
# Each occurrence of a search_term has a score that is smaller the older the
# occurrence happened. We subtract the amount of time between now and the
# moment it happened from the total time any occurrence is valid to happen. E.g.:
# The expiration time is 100 days and an occurrence happened 3 days ago.
# Therefore the score is 97. Them we sum every score to get the total score
# for a search term.
def self.occurrences_scores
ActiveSupport::OrderedHash[*ActiveRecord::Base.connection.execute(
joins(:occurrences).
select("search_terms.id, sum(#{SearchTermOccurrence::EXPIRATION_TIME.to_i} - extract(epoch from (now() - search_term_occurrences.created_at))) as value").
where("search_term_occurrences.created_at > ?", DateTime.now - SearchTermOccurrence::EXPIRATION_TIME).
group("search_terms.id").
order('value DESC').
to_sql
).map {|result| [result['id'].to_i, result['value'].to_i]}.flatten]
end
def calculate_occurrence(occurrences_scores)
max_score = occurrences_scores.first[1]
(occurrences_scores[id]/max_score.to_f)*100
end
def calculate_relevance(valid_occurrences)
indexed = valid_occurrences.last.indexed.to_f
return 0 if indexed == 0
total = valid_occurrences.last.total.to_f
(1 - indexed/total)*100
end
def calculate_score(occurrences_scores)
valid_occurrences = occurrences.valid
if valid_occurrences.present?
# These scores vary from 1~100
self.occurrence_score = calculate_occurrence(occurrences_scores)
self.relevance_score = calculate_relevance(valid_occurrences)
else
self.occurrence_score = 0
self.relevance_score = 0
end
self.score = (occurrence_score * relevance_score)/100.0
self.save!
end
end