Rails: Generate Unique Random Number for populating a CSS class String How To?

问题

So let's say we have a rails view with this code:

<h1>Users who have the <%= @title.name %> Title</h1>
<ul>
  <% @title.users.each do |user| %>
    <li><%= user.username %> <div class="rw-ui-container rw-urid-X"></div></li>
  <% end %>
</ul>

And what we want to do is to automatically print this line:

<div class="rw-ui-container rw-urid-X"></div>

Right aside each username the loop throws at us BUT we want X to be a different unique random number each time...

How can this be accomplished?

回答1:

May be this solution can help you: 1. You can use user_id as first part of the random X to ensure that another user doesn't have it 2. Second part is time in UTC format to set X different each time 3. Third part is just a standart random func. You haven't use it if you want.

<h1>Users who have the <%= @title.name %> Title</h1>
<ul>
  <% @title.users.each do |user| %>
    <li><%= user.username %> <div class="rw-ui-container rw-urid-<%= "#{user_id}#{Time.now.utc.to_i}#{rand(100000)}".to_i %>"></div></li>
  <% end %>
</ul>

回答2:

css_arr = ["rw-ui-container rw-urid-1","rw-ui-container rw-urid-2","rw-ui-container rw-urid-3"]

<div class="<%= css_arr.sample %>"></div>

回答3:

Well You could easily add a new field to user table call uuid or give it any name that you like and assign a unique id using the gem called uuid

This help ensure that you have uniqueness in X section and also on refresh the value wont change as you mention in one of your comment

so here how your X code would look like

<% @title.users.each do |user| %>
    <li><%= user.username %> <div class="rw-ui-container rw-urid-<%=user.uuid %>"></div></li>
  <% end %>

来源：https://stackoverflow.com/questions/11153244/rails-generate-unique-random-number-for-populating-a-css-class-string-how-to