Class: Silver::Search

Inherits:
Object
  • Object
show all
Defined in:
lib/silver/search.rb

Overview

Searches an indexed database. What else would it do?

Instance Method Summary collapse

Constructor Details

#initialize(query, key, redis_options = {}, number = 30, offset = 0) ⇒ Search

Takes a query and a redis key from a previous indexing. There is an optional offset that can be used to paginate. It defaults to returning 30 results.

Example, query picture captions for “Barack Obama”:

search = Silver::Search.new("barack obama","picturecaption")



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# File 'lib/silver/search.rb', line 15

def initialize(query,key,redis_options={},number=30,offset=0)
    @query = query
    @key = key
    @number = number
    @offset = offset
    @r = Redis.new(redis_options)
    @r.select 12
end

Instance Method Details

#find_matching_phones(phones) ⇒ Object

Takes an array of metaphones and returns the matching keys in the index. Since we are using double metaphone, it unions the results for the two possible metaphones.i



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# File 'lib/silver/search.rb', line 56

def find_matching_phones(phones)
    phones.map! do |phone|
        if phone
            "#{@key}:#{phone}"
        else
            nil
        end
    end
    phones = @r.zunionstore "temp", phones.compact
    phones = @r.zrevrange "temp", 0, -1
    phones
end

#morph_words ⇒ Object

Takes the instance’s query, splits it into words, metaphones each word and returns the array of metaphoned words.



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# File 'lib/silver/search.rb', line 47

def morph_words
    words = @query.split(/[^a-zA-Z0-9]/)
    morphed_words = words.map{|word| [word,Text::Metaphone.double_metaphone(word)]}
    morphed_words
end

#perform(&accessor) ⇒ Object

Send a query to be metaphoned, finds the matching ids for the query and then returns the results. Finally it only returns entries that are shared by both words.

Takes a block that takes an id and then queries the database for that row. Again, Silver can be used for services that “row” is a bad metaphor like REST apis. However, it is easy to write.

Ex:

search.perform{|id| Picture.get(id) }



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# File 'lib/silver/search.rb', line 34

def perform(&accessor)
    morphed_words = morph_words
    morphed_words.map! do |word|
        phones = word[1]
        phones = self.find_matching_phones(phones)
        phones
    end
    results = morphed_words.reduce{|memo,obj| memo & obj}.slice(@offset,@number)
    results.map{|result| accessor.call(result)}
end