def foreign_keys(table_name)
fk_info = select_all %Q{
SELECT t2.relname AS to_table, a1.attname AS column, a2.attname AS primary_key, c.conname AS name, c.confdeltype AS dependency
FROM pg_constraint c
JOIN pg_class t1 ON c.conrelid = t1.oid
JOIN pg_class t2 ON c.confrelid = t2.oid
JOIN pg_attribute a1 ON a1.attnum = c.conkey[1] AND a1.attrelid = t1.oid
JOIN pg_attribute a2 ON a2.attnum = c.confkey[1] AND a2.attrelid = t2.oid
JOIN pg_namespace t3 ON c.connamespace = t3.oid
WHERE c.contype = 'f'
AND t1.relname = '#{table_name}'
AND t3.nspname = ANY (current_schemas(false))
ORDER BY c.conname
}
fk_info.map do |row|
options = {:column => row['column'], :name => row['name'], :primary_key => row['primary_key']}
options[:dependent] = case row['dependency']
when 'c' then :delete
when 'n' then :nullify
when 'r' then :restrict
end
ForeignKeyDefinition.new(table_name, row['to_table'], options)
end
end