Setting a default value to a param attribute in the controller if it is nil?

Question

I'm enabling users to sort posts by created_at and total_votes:

posts_controller.rb:

@posts = current_user.subscribed_posts.paginate(:page => params[:page],
                                                :per_page => 5,
                                                :order => params[:order_by])

show.html.erb:

  <span class="comment-tab <% if params[:order_by] == 'created_at DESC' %>current-tab<% end %>"><%= link_to 'Date (DESC)', post_path(@post, :order_by => "created_at DESC") %></span>
  <span class="comment-tab <% if params[:order_by] == 'created_at ASC' %>current-tab<% end %>" ><%= link_to 'Date (ASC)', post_path(@post, :order_by => "created_at ASC") %></span>
  <span class="comment-tab <% if params[:order_by] == 'total_votes DESC' or params[:order_by].nil? %>current-tab<% end %>"><%= link_to 'Votes', post_path(@post, :order_by => "total_votes DESC") %></span>

I would like :order_by to have the value of total_votes DESC by default (when it is nil).

What's the best way of doing this?

Kyle · Accepted Answer · 2014-07-09 12:56:57Z

9

In the controller

params[:order_by] ||= "total_votes DESC"

Or

# fetch returns the default value if the key is not present
params.fetch(:order_by, "total_votes DESC")

Hash#fetch

edited Jul 9, 2014 at 12:56

answered Mar 14, 2012 at 3:53

Kyle

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1 Comment

CambridgeMike Over a year ago

Be careful with ||= for setting defaults. params[:my_bool] ||= true will always be true, not true iff it's not defined.

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