I am using MySQL2 in Ruby to query a database. What is a direct way to check whether the result of a query is empty? The code looks like:
require 'mysql2'
client = Mysql2::Client.new(:host => "localhost", :username => "root")
results = client.query("SELECT * FROM users WHERE group='githubbers'")
The Mysql2
documentation is indeed very poor. But by inspecting the type of results
you will notice that it is a Mysql2::Result
which contains 3 methods. The one that you are interested in is count
(or alias size
) which will return the number of rows of the result.
From here you can easily check if it is 0
:
(results.count == 0)
Alternatively you could open the Mysql2::Result
class and add the method empty?
yourself:
class Mysql2::Result
def empty?
(count == 0)
end
end
And then you can just do:
results.empty?
0 == results.size
will return true
if results
is empty. AFAIK there is no direct method (such as Array#empty?
) , but you could monkey patch it.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.