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Contents
module Neo4j
module Core
module Index
# A Utility class that can be used to make it easier to create unique entities. It uses {Neo4j::Core::Index::Indexer#put_if_absent}.
#
# @see Indexer#put_if_absent
#
# @example
# index = index_for_type(:exact)
# Neo4j::Core::Index::UniqueFactory.new(:email, index) { |k,v| Neo4j::Node.new(k => v) }.get_or_create(:email, 'foo@gmail.com')
#
class UniqueFactory
# @param [Symbol] key only one key is possible
# @param [Java::Neo4j] index the lucene index (see #index_for_type)
# @yield a proc for initialize each created entity
def initialize(key, index, &entity_creator_block)
@key = key
@index = index
@entity_creator_block = entity_creator_block || Proc.new{|k,v| Neo4j::Node.new(key.to_s => v)}
end
# Get the indexed entity, creating it (exactly once) if no indexed entity exists.
# There must be an index on the key
# @param [Symbol] key the key to find the entity under in the index.
# @param [String, Fixnum, Float] value the value the key is mapped to for the entity in the index.
# @param [Hash] props optional properties that the entity will have if created
# @yield optional, make it possible to initialize the created node in a block
def get_or_create(key, value, props=nil, &init_block)
tx = Neo4j::Transaction.new
result = @index.get(key.to_s, value).get_single
return result if result
created = @entity_creator_block.call(key,value)
result = @index.put_if_absent(created._java_entity, key.to_s, value)
if result.nil?
props.each_pair{|k,v| created[k.to_s] = v} if props
init_block.call(result) if init_block
result = created
else
created.del
end
tx.success
result
ensure
tx.finish
end
end
end
end
end
Version data entries
11 entries across 11 versions & 1 rubygems