URL custom validator

app/models/link.rb

@@ -1,8 +1,8 @@
 class Link < ApplicationRecord
   belongs_to :user, optional: true # Prevent ActiveRecord::RecordInvalid
 
-  validates :url, presence: true, length: { minimum: 5 }
-  validates :description, presence: true, length: { minimum: 5 }
+  validates :url, presence: true, url: true, length: { minimum: 3 }
+  validates :description, presence: true, length: { minimum: 3 }
 
   has_many :votes
 end

app/validators/url_validator.rb

@@ -0,0 +1,12 @@
+class UrlValidator < ActiveModel::EachValidator
+  def validate_each(record, attribute, value)
+    record.errors[attribute] << (options[:message] || "Must be a valid URL") unless url_valid?(value)    
+  end
+
+  # a URL may be technically well-formed but may 
+  # not actually be valid, so this checks for both.
+  def url_valid?(url)
+    url = URI.parse(url) rescue false
+    url.kind_of?(URI::HTTP) || url.kind_of?(URI::HTTPS)
+  end 
+end