Add a random string while updating attribute

Question

I am looking for a method that can generate a random string in the starting of the email field while updating the record.

def update
  @user = User.find_by_id(4)
  @user.email = #method to update email with random string
end

So if I have the email record abc@gmail.com and I want to update it like this:

dssaakj123_abc@gmail.com

How it can be done in rails?

Have you check this [Question: How best to generate a random string in Ruby](http://stackoverflow.com/questions/88311/how-best-to-generate-a-random-string-in-ruby)? — Gagan Gami, Dec 02 '15 at 10:34
Do you intend to prepend the email with the random string *once* or on *every* update? — davegson, Dec 02 '15 at 10:44
I'll just warn you that the current solutions will all lead to emails updated on every update call. Resulting in `foo1_foo2_foo3_.._foo100_champ@gmail.com`. I this really what you want? — davegson, Dec 02 '15 at 11:14

Yury Lebedev · Accepted Answer · 2015-12-02T12:40:33.320

4

You can use the SecureRandom library:

@user.email = "#{SecureRandom.hex(10)}_#{user.email}"

edited Dec 02 '15 at 12:40

answered Dec 02 '15 at 10:22

Yury Lebedev

3,985
19
26

how can i get a random string only in digits ? – user4965201 Dec 02 '15 at 10:51
Use `'%011d' % rand(1e10)` instead of `SecureRandom.hex(10)`. To change the number of digits in the string change the number after `e` here: `1e10` – Yury Lebedev Dec 02 '15 at 10:53
SecureRandom is part of [the standard lib](http://ruby-doc.org/stdlib-2.2.0/libdoc/securerandom/rdoc/SecureRandom.html), no ActiveSupport needed. – steenslag Dec 02 '15 at 12:37

Dusht · Answer 2 · 2015-12-02T10:35:17.127

2

Why not use SecureRandom?

require 'securerandom'
random_string = SecureRandom.hex # provide argument to limit the no. of characters

# outputs: 5b5cd0da3121fc53b4bc84d0c8af2e81 (i.e. 32 chars of 0..9, a..f)

For appending before email, you can do something like

@user.email = "#{SecureRandom.hex(5))_#{@user.email}" # 5 is no. of characters

Hope it helps!

edited Dec 02 '15 at 10:35

answered Dec 02 '15 at 10:29

Dusht

4,712
3
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just a small thing: i think the author if the question wanted to prepend a random string to the email address, not replace the whole string before `@` completely – Yury Lebedev Dec 02 '15 at 10:33
@YuryLebedev Yes it might be the case. But he didn't mentioned. It might be the case, he wants to replace before `@`. Author needs to confirm on this.:( – Dusht Dec 02 '15 at 10:35
Yes, you are right. He mentioned at the starting, that he wants to `generate a random string in the starting of the email`. – Dusht Dec 02 '15 at 10:38

score 1 · Answer 3 · answered Dec 02 '15 at 10:21

1

(1..8).map{|i| ('a'..'z').to_a[rand(26)]}.join

8 is the number of characters you want to generate randomly.

answered Dec 02 '15 at 10:21

Vrushali Pawar

3,753
1
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Dipak Gupta · Answer 4 · 2015-12-02T10:44:03.920

-1

create an action in your application controller like this :

private 
  def generate_random_string
    SecureRandom.urlsafe_base64(nil, false)
  end

And use it like this in any controller you want:

def update
  @user = User.find_by_id(4)
  @user.email = generate_random_string + @user.email
end

edited Dec 02 '15 at 10:44

answered Dec 02 '15 at 10:25

Dipak Gupta

7,321
1
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32

2

Adding this method to `before_update` will prepend to the current email_adress on each update. Resulting in `foo1_foo2_foo3_dipak@gmail.com`. I doubt this is useful or required. You should use `before_create` instead. – davegson Dec 02 '15 at 10:27
`before_action` is a method for controllers, it has nothing to do with models – Yury Lebedev Dec 02 '15 at 10:28
Yes it will, But I thought they need same functionality. – Dipak Gupta Dec 02 '15 at 10:28
@YuryLebedev, the answer states: "before_update *in your model*" – davegson Dec 02 '15 at 10:29
Thanks @TheCha͢mp fixed typo. – Dipak Gupta Dec 02 '15 at 10:30
what if i want a method in the application_helper and create a method there and use it in the controller , this is because i am using this method in different model as well – user4965201 Dec 02 '15 at 10:31
You need to add it in every model, If you want to save it in db. Where you want to do this ? – Dipak Gupta Dec 02 '15 at 10:32
Yes @TheCha͢mp It will add on each update. and question is for same. – Dipak Gupta Dec 02 '15 at 10:33
@Dipak in the controller i want to call the method and pass the email as the arguement – user4965201 Dec 02 '15 at 10:34
Yes, the question states that, but I assume he did not think of that behavior... you should correct thinking errors as well, or assure he really wants this useless functionality. – davegson Dec 02 '15 at 10:34
So you can add action in application controller and then call that action in any controller where you want. Updating answer – Dipak Gupta Dec 02 '15 at 10:36

score -1 · Answer 5 · answered Dec 02 '15 at 10:56

I hope this will help you.

def update
  @user = User.find_by_id(4)
  @user.email = "#{generate_random_string(8)}_#{@user.email}"
  ## You can pass any length to generate_random_string method, in this I have passed 8.
end

private

def generate_random_string(length)
  options = { :length => length.to_i, :chars => ('a'..'z').to_a + ('A'..'Z').to_a + ('0'..'9').to_a }
  Array.new(options[:length]) { options[:chars].to_a[rand(options[:chars].to_a.size)] }.join
end

how does this add to the existing answers in any way? – davegson Dec 02 '15 at 11:12 — davegson, Dec 02 '15 at 11:12

Add a random string while updating attribute

5 Answers5