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Contents
module ETL #:nodoc:
module Processor #:nodoc:
# Row processor that checks whether or not the row has already passed
# through the ETL processor, using the key fields provided as the keys
# to check.
class CheckUniqueProcessor < ETL::Processor::RowProcessor
# The keys to check
attr_accessor :keys
# Initialize the processor
# Configuration options:
# * <tt>:keys</tt>: An array of keys to check against
def initialize(control, configuration)
super
@keys = configuration[:keys]
end
# A Hash of keys that have already been processed.
def compound_key_constraints
@compound_key_constraints ||= {}
end
# Process the row. This implementation will only return a row if it
# it's key combination has not already been seen.
#
# An error will be raised if the row doesn't include the keys.
def process(row)
ensure_columns_available_in_row!(row, keys, 'for unicity check')
key = (keys.collect { |k| row[k] }).join('|')
unless compound_key_constraints[key]
compound_key_constraints[key] = 1
return row
end
end
end
end
end
Version data entries
4 entries across 4 versions & 3 rubygems