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Contents
module ETL #:nodoc:
module Processor #:nodoc:
# A row level processor that provides surrogate keys
class SurrogateKeyProcessor < ETL::Processor::RowProcessor
attr_accessor :destination
attr_accessor :table
attr_accessor :column
attr_accessor :target
# Initialize the surrogate key generator
#
# Configuration options
# * <tt>:query</tt>: If specified it contains a query to be used to
# locate the last surrogate key. If this is specified then :target
# must also be specified.
# * <tt>:target</tt>: The target connection
# * <tt>:destination</tt>: The destination column name (defaults to :id)
def initialize(control, configuration)
super
@table = configuration[:table]
@column = configuration[:column] || 'id'
@target = configuration[:target]
if configuration[:query]
raise ControlError, "Query option is no longer value, use :column and :table instead"
end
if table
@surrogate_key = ETL::Engine.connection(target).select_value("SELECT max(#{column}) FROM #{table_name}")
end
#puts "initial surrogate key: #{@surrogate_key}"
@surrogate_key = 0 if @surrogate_key.blank?
@surrogate_key = @surrogate_key.to_i
#puts "surrogate key: #{@surrogate_key}"
@destination = configuration[:destination] || :id
end
# Add a surrogate key to the row
def process(row)
if row
#puts "processing row #{row.inspect}"
@surrogate_key += 1
#puts "adding surrogate key to row: #{@surrogate_key}"
row[destination] = @surrogate_key
row
end
end
private
def table_name
ETL::Engine.table(table, ETL::Engine.connection(target))
end
end
end
end
Version data entries
23 entries across 23 versions & 9 rubygems