ruby on rails sleep

ruby on rails分页的方法

There are several pagination methods in Rails; we’ll use one of the simplest and most robust, called will_paginate. To use it, we need to include both the will_paginate gem and bootstrap-will_paginate, which configures will_paginate to use Bootstrap’s pagination styles. The updated Gemfile appears in Listing 9.31.

在User的index.html.erb中加入

<% provide(:title, 'All users') %>
<h1>All users</h1>
<%= will_paginate %>
<ul class="users">
  <% @users.each do |user| %>
    <li>
      <%= gravatar_for user, size: 52 %>
      <%= link_to user.name, user %>
    </li>
  <% end %>
</ul>
<%= will_paginate %>

Using the paginate method, we can paginate the users in the sample application by using paginate in place of all in the index action (Listing 9.35). Here the :page parameter comes from params[:page], which is generated automatically by will_paginate.

def index
    @users = User.paginate(page: params[:page])
  end

以上是用来分页的。

admin?

The migration to add a boolean admin attribute to users. 
db/migrate/[timestamp]_add_admin_to_users.rb
class AddAdminToUsers < ActiveRecord::Migration
  def change
    add_column :users, :admin, :boolean, default: false
  end
end

由于admin这个属性不是attr_accessible 的，所以只能用以下类似代码

admin = User.create!(name: "Example User",
                         email: "[email protected]",
                         password: "foobar",
                         password_confirmation: "foobar")
    admin.toggle!(:admin)

<li>
  <%= gravatar_for user, size: 52 %>
  <%= link_to user.name, user %>
  <% if current_user.admin? && !current_user?(user) %>
    | <%= link_to "delete", user, method: :delete,
                                  data: { confirm: "You sure?" } %>
  <% end %>
</li>

如果要delete一个用户，必须是admin或者是一个用户