How to fetch a random record in rails?

Question

I am trying to fetch a random record in rails, to render in my home page.

I have a post model with content and title attributes. Lets say i wanted to fetch a random post(content and title) for some reason, How can i go about it in ruby. Thanks in advance.

do you want to fetch a random post from your database, or to create random content ? — m_x, Mar 03 '13 at 10:12
Sorry if i was unclear, I want to fetch a random post not create. — , Mar 03 '13 at 15:20

score 4 · Answer 1 · answered Mar 03 '13 at 11:01

4

You might find this gem handy : Faker

It allows to generate random strings with some meaning.

For example, a name :

Faker::Name.name => “Bob Hope”

Or an e-mail

Faker::Internet.email

In addition to this gem, if you want to be able to generate mock models very easily, I recommend the gem Factory Girl

It allows you to create factories for your model, sou you can generate a model with random attributes quickly.

answered Mar 03 '13 at 11:01

Intrepidd

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Thanks for getting back to me and Sorry if i was unclear, I want to fetch a random post not create. If i am correct the faker gem creates random attributes. I am looking for fetch attributes at random to render in a view. – Mar 03 '13 at 15:22

score 1 · Answer 2 · answered Mar 03 '13 at 17:36

Posting another answer since the first one answered to an unclear question.

As @m_x said, you can use RANDOM() for SQL.

If you don't mind loading all the dataset, you can do it in ruby as well :

Post.all.sample

This will select one random record from all Posts.

score 1 · Answer 3 · answered Sep 29 '13 at 11:10

I know this is an old question, but since no answer was chosen, answering it might be helpful for other users.

I think the best way to go would be generating a random offset in Ruby and using it in your Active Record statement, like so:

Thing.limit(1).offset(rand(Thing.count)).first

This solution is also performant and portable.

score 0 · Answer 4 · edited May 23 '17 at 10:25

0

In your post controller,

def create
  @post = Post.new(params[:post])
  if you_want_some_random_title_and_content
    title_length = 80 #choose your own
    content_length = 140 #choose your own
    @post.title = (0...title_length).map{(65+rand(26)).chr}.join
    @post.content = (0...content_length).map{(65+rand(26)).chr}.join
  end

  if @post.save
    redirect_to @post
  else
    render 'new'
  end
end

Using Kent Fedric's way to generate random string

edited May 23 '17 at 10:25

Community

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answered Mar 03 '13 at 10:23

Jason Kim

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Titles and contents in the real world usually have spaces in them… – Aleksei Matiushkin Mar 03 '13 at 12:28
That may be true, but OP did not mention that. – Jason Kim Mar 03 '13 at 21:01

score 0 · Answer 5 · answered Mar 03 '13 at 17:00

0

unfortunately, there is no database-agnostic method for fetching a random record, so ActiveRecord does not implement any.

For postgresql you can use :

Post.order( 'RANDOM()' ).first

To fetch one random post.

Additionnally, i usually create a scope for this:

class Post < ActiveRecord::Base
  scope :random_order, ->{ order 'RANDOM()' }
end

so if you change your RDBMS, you just have to change the scope.

answered Mar 03 '13 at 17:00

m_x

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More along the lins of what i need. Thnaks. – Mar 03 '13 at 21:07

How to fetch a random record in rails?

5 Answers5