Method: Axiom::Relation#one

Defined in:

lib/axiom/relation.rb

#one ⇒ Tuple

Return a tuple if the relation contains exactly one tuple

Examples:

tuple = relation.one

Returns:

• (Tuple)

Raises:

• (NoTuplesError) —

  raised if no tuples are returned

• (ManyTuplesError) —

  raised if more than one tuple is returned

# File 'lib/axiom/relation.rb', line 129

def one
  tuples = to_a
  assert_exactly_one_tuple(tuples.size)
  tuples.first
end