Class: Linkage::ScoreSets::Database

Inherits:
Linkage::ScoreSet show all
Includes:
Helpers::Database
Defined in:
lib/linkage/score_sets/database.rb

Overview

ScoreSets::Database is an implementation of Linkage::ScoreSet for saving scores in a relational database.

Scores are saved in a database table with the following columns:

  • comparator_id (integer)
  • id_1 (string)
  • id_2 (string)
  • score (float)

You can setup a database connection in a few different ways. By default, a SQLite database with the filename of scores.db will be created in the current working directory. If you want something different, you can either specify a Sequel-style URI, provide connection options for Sequel.connect, or you can just specify a Sequel::Database object to use.

There are a couple of non-Sequel connection options:

  • :filename - specify filename to use for a SQLite database
  • :dir - specify the parent directory for a SQLite database

In addition to connection options, there are behavioral options you can set. By default, the table name used is called scores, but you change that by setting the :table_name option in the second options hash. If the table already exists, an ExistsError will be raised unless you set the :overwrite option to a truthy value in the second options hash.

Constant Summary collapse

DEFAULT_OPTIONS = 
{
  :filename => 'scores.db'
}

Instance Method Summary collapse

Methods included from Helpers::Database

#database_connection

Methods inherited from Linkage::ScoreSet

klass_for, register

Constructor Details

#initialize(connection_options = {}, options = {}) ⇒ Database

Returns a new instance of Database.



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# File 'lib/linkage/score_sets/database.rb', line 44

def initialize(connection_options = {}, options = {})
  @database = database_connection(connection_options, DEFAULT_OPTIONS)
  @table_name = options[:table_name] || :scores
  @overwrite = options[:overwrite]
end

Instance Method Details

#add_score(comparator_id, id_1, id_2, score) ⇒ Object 



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# File 'lib/linkage/score_sets/database.rb', line 82

def add_score(comparator_id, id_1, id_2, score)
  raise "not in write mode" if @mode != :write

  @dataset.insert({
    :comparator_id => comparator_id,
    :id_1 => id_1,
    :id_2 => id_2,
    :score => score
  })
end

#close ⇒ Object 



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# File 'lib/linkage/score_sets/database.rb', line 108

def close
  @mode = nil
end

#each_pair {|current_pair| ... } ⇒ Object

Yields:

  • (current_pair) 


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# File 'lib/linkage/score_sets/database.rb', line 93

def each_pair
  raise "not in read mode" if @mode != :read

  current_pair = nil
  @dataset.order(:id_1, :id_2, :comparator_id).each do |row|
    if current_pair.nil? || current_pair[0] != row[:id_1] || current_pair[1] != row[:id_2]
      yield(*current_pair) unless current_pair.nil?
      current_pair = [row[:id_1], row[:id_2], {}]
    end
    scores = current_pair[2]
    scores[row[:comparator_id]] = row[:score]
  end
  yield(*current_pair) unless current_pair.nil?
end

#open_for_reading ⇒ Object 



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# File 'lib/linkage/score_sets/database.rb', line 50

def open_for_reading
  raise "already open for writing, try closing first" if @mode == :write
  return if @mode == :read

  if !@database.table_exists?(@table_name)
    raise MissingError, "#{@table_name} table does not exist"
  end

  @dataset = @database[@table_name]
  @mode = :read
end

#open_for_writing ⇒ Object 



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# File 'lib/linkage/score_sets/database.rb', line 62

def open_for_writing
  raise "already open for reading, try closing first" if @mode == :read
  return if @mode == :write

  if @overwrite
    @database.drop_table?(@table_name)
  elsif @database.table_exists?(@table_name)
    raise ExistsError, "#{@table_name} table exists and not in overwrite mode"
  end

  @database.create_table(@table_name) do
    Integer :comparator_id
    String :id_1
    String :id_2
    Float :score
  end
  @dataset = @database[@table_name]
  @mode = :write
end