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Contents
module ROM
class Relation
# Materializes a relation and exposes interface to access the data
#
# @api public
class Loaded
include Enumerable
# Coerce loaded relation to an array
#
# @return [Array]
#
# @api public
alias_method :to_ary, :to_a
# Source relation
#
# @return [Relation]
#
# @api private
attr_reader :source
# Materialized relation
#
# @return [Object]
#
# @api private
attr_reader :collection
# @api private
def initialize(source, collection = source.to_a)
@source = source
@collection = collection
end
# Yield relation tuples
#
# @yield [Hash]
#
# @api public
def each(&block)
return to_enum unless block
collection.each { |object| yield(object) }
end
# @api public
def new(collection)
self.class.new(source, collection)
end
# Returns a single tuple from the relation if there is one.
#
# @raise [ROM::TupleCountMismatchError] if the relation contains more than
# one tuple
#
# @api public
def one
if collection.count > 1
raise(
TupleCountMismatchError,
'The relation consists of more than one tuple'
)
else
collection.first
end
end
# Like [one], but additionally raises an error if the relation is empty.
#
# @raise [ROM::TupleCountMismatchError] if the relation does not contain
# exactly one tuple
#
# @api public
def one!
one || raise(
TupleCountMismatchError,
'The relation does not contain any tuples'
)
end
end
end
end
Version data entries
18 entries across 18 versions & 1 rubygems