Check whether a string contains numbers - ruby-on-rails

Question

I have input values like:
string = "devid"
string = "devid123"
string = "devid.123.devid"
I need to sort strings that contain .(number)., for example "devid.123.devid". How can I separate only strings that consist of .(numbers). like .123.? Help me find a solution.
In a controller, I have:
#person = Person.new
personname = params['personname']
if personname.match("/\d+/")
#person.person_name = personname
#person.save()
result = 'true'
end
When I execute this code, I get "devid123" and "devid.123.devid".

Answer 1

If its certain that the format of the valid personname is always
<string>.<number>.<string>
You can try using :[regex, index] method for strings in ruby.
https://ruby-doc.org/core-2.6.1/String.html#method-i-5B-5D
So if
personname = "devid.123.devid"
s[/(.*)(\.\d+\.)(.*)/, 2] = ".123."
There are three different groups in the regex (.*)(\.\d+\.)(.*).
Matches anything
Matches a .<number>.
Matches anything
So based on this regex, the second group should provide you .<number>. which, I hope, is what you need.
Tested with Ruby 2.4.1

Answer 2

If I understand this correctly you only want a string where the digits are preceded by .. If so you need to modify your regex to be /\.\d+/
#person = Person.new
personname=params['personname']
if personname.match("/\.\d+/")
#person.person_name = personname
#person.save
result = 'true'
end
But this sounds like logic you should be handling in the model, since this is tagged as rails and not plain old ruby
controller
class PersonController
def create
if #person = Person.create(params)
result = 'true'
else
result = 'false'
end
# whatever you doing with result
end
end
person.rb
class Person < ApplicationRecord
validates :personname, format: { with: /\.\d+\./, message: 'must include digits' }
end
You can play with the regex # rubular