Reproduce Sequel's validates_min_length validation - ruby

Question

I'm hoping to reproduce Sequel's validates_min_length errors for a Bcrypt-encrypted password. I can't use the validation as it will test the password hash, rather than the un-encrypted text.
I'm having difficulty getting the password= method to produce the desired errors.
Un-encrypted-password logic
require 'sequel'
DB = Sequel.sqlite
DB.create_table(:users) do
primary_key :id
String :name, null: false, unique: true
String :password, null: false
end
class User < Sequel::Model
plugin :validation_helpers
def validate
super
validates_presence [:name,:password]
validates_unique [:name]
validates_min_length 8, :password
end
end
IRB:
irb(main):001:0> u=User.new(name: 'foobar', password: 'Pa55w0rd')
=> #<User #values={:name=>"foobar", :password=>"Pa55w0rd"}>
irb(main):002:0> u.valid?
=> true
irb(main):003:0> u.password=nil
=> nil
irb(main):004:0> u
=> #<User #values={:name=>"foobar", :password=>nil}>
irb(main):005:0> u.valid?
=> false
irb(main):007:0> u.errors
=> {:password=>["is not present", "is shorter than 8 characters"]}
irb(main):008:0> u.password='foo'
=> "foo"
irb(main):009:0> u
=> #<User #values={:name=>"foobar", :password=>"foo"}>
irb(main):010:0> u.valid?
=> false
irb(main):011:0> u.errors
=> {:password=>["is shorter than 8 characters"]}
Encrypted-password logic
require 'sequel'
require 'bcrypt'
DB = Sequel.sqlite
DB.create_table(:users) do
primary_key :id
String :name, null: false, unique: true
String :password_hash, null: false
end
class User < Sequel::Model
plugin :validation_helpers
include BCrypt
def validate
super
validates_presence [:name,:password]
validates_unique [:name]
end
def password
# check for :password_hash existence to ensure that validates_presence :password works correctly
#password ||= Password.new(password_hash) if password_hash
end
def password=(new_password)
# add validation errors
errors.add(:password, 'is shorter than 8 characters') if new_password==nil || new_password.length < 8
if new_password == nil
#password = nil
else
#password = Password.create(new_password)
end
self.password_hash = #password
end
end
IRB:
irb(main):001:0> u=User.new(name: 'foobar', password: 'Pa55w0rd')
=> #<User #values={:name=>"foobar", :password_hash=>"$2a$10$K3UALPYz/bb5bdrGmbq22eRM31A6rU3kqkbzcU4.6J5APQVSqxQo6"}>
irb(main):002:0> u.valid?
=> true
irb(main):003:0> u.password=nil
=> nil
irb(main):004:0> u
=> #<User #values={:name=>"foobar", :password_hash=>nil}>
irb(main):005:0> u.valid?
=> false
irb(main):006:0> u.errors
=> {:password=>["is not present"]}
irb(main):007:0> u.password='foo'
=> "foo"
irb(main):009:0> u
=> #<User #values={:name=>"foobar", :password_hash=>"$2a$10$lA6fsKXSvl5cd.Zl53qEqOzxk1LPehvGujWaXwcf1//IUc82CmowC"}>
irb(main):008:0> u.valid?
=> true
Both invalid passwords (nil,'foo') are missing the is shorter than 8 characters error.
What am I missing?
Versions:
$ sequel --version
sequel 5.7.1

Answer 1

#password is not actually shorter than 8 characters. BCrypt::Password is a subclass of string, and it will have the same length as the password hash. You would have to set #password in password= if you wanted to use a validation to ensure the size of the password.

Answer 2

I am not 100% sure on functionality but this should work for you.
def validate
super
validates_presence [:name,:password]
validates_unique [:name]
validates_min_length 8, :password
end
def password=(new_password)
return unless #password = new_password and #password.to_s.length >= 8
self.password_hash = Password.create(password)
end
I added the actual length validation to validate so that valid? will return false. Additionally I cleaned up the password= method a bit.
So now password= has a guard clause that simply returns if the password is invalid as defined by "less than 8 characters".
Otherwise we create a new password_hash via Password.create and assign it to #password_hash.
Please note: There is a functional change between my proposed code and yours which is that #password_hash is not overwritten when the "new_password" is invalid. This seemed counter intuitive to me that an invalid password could overwrite an existing and valid password_hash thus my change in implementation.
All that being said your best bet is actually to go with this
class User < Sequel::Model
plugin :validation_helpers
include BCrypt
attr_accessor :password
def validate
super
validates_presence [:name,:password]
validates_unique [:name]
validates_min_length 8, :password
end
def before_save
self.password_hash = Password.create(password)
end
end
This avoids all the manipulation and will only create a password_hash (which is all you actually need) if the model passes validation checks

Answer 3

This works as desired:
require 'sequel'
require 'bcrypt'
DB = Sequel.sqlite
DB.create_table(:users) do
primary_key :id
String :name, null: false, unique: true
String :password_hash, null: false
end
class User < Sequel::Model
plugin :validation_helpers
include BCrypt
def validate
super
validates_presence [:name,:password]
validates_unique [:name]
errors.add(:password, 'is shorter than 8 characters') if #password==nil || #password.length < 8
end
def password
Password.new(password_hash) if password_hash
end
def password=(new_password)
# uncomment to prevent bad passwords from changing a good password; probably needs to include a non-terminating error message
# return if new_password==nil || new_password.length < 8
# store clear-text password for validation
#password = new_password
#modify password hash accordingly
self.password_hash = if new_password then Password.create(new_password) else nil end
end
end