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Contents
module ETL #:nodoc:
module Transform #:nodoc:
# Transform which walks up the hierarchy tree to find a value of the current level's value
# is nil.
#
# TODO: Let the resolver be implemented in a class so different resolution methods are
# possible.
class HierarchyLookupTransform < ETL::Transform::Transform
# The name of the field to use for the parent ID
attr_accessor :parent_id_field
# The target connection name
attr_accessor :target
# Initialize the transform
#
# Configuration options:
# * <tt>:target</tt>: The target connection name (required)
# * <tt>:parent_id_field</tt>: The name of the field to use for the parent ID (defaults to :parent_id)
def initialize(control, name, configuration={})
super
@parent_id_field = configuration[:parent_id_field] || :parent_id
@target = configuration[:target]
end
# Transform the value.
def transform(name, value, row)
if parent_id = row[parent_id_field]
# TODO: should use more than just the first source out of the control
parent_id, value = lookup(name,
control.sources.first.configuration[:table], parent_id, parent_id_field)
until value || parent_id.nil?
# TODO: should use more than just the first source out of the control
parent_id, value = lookup(name,
control.sources.first.configuration[:table], parent_id, parent_id_field)
end
end
value
end
# Lookup the parent value.
def lookup(field, table, parent_id, parent_id_field)
q = "SELECT #{parent_id_field}, #{field} FROM #{table} WHERE id = #{parent_id}"
row = ETL::Engine.connection(target).select_one(q)
return row[parent_id_field.to_s], row[field.to_s]
end
end
end
end
Version data entries
23 entries across 23 versions & 9 rubygems