Question

I am using running a simple find all and paginating with willpaginate, but I’d also like to have the query sorted by the user. The first solution that came to mind was just use a params[:sort]

http://localhost:3000/posts/?sort=created_at+DESC  @posts = Post.paginate :page => params[:page], :order => params[:sort] 

But the problem with his approach is that the query is defaulting as sorting by ID and I want it to be created_at.

Is this a safe approach to sorting and is there a way to default to created_at?

Answer 1

I’d use a named scope for providing the default order (available since Rails 2.1).

You’d add the scope in your Post model:

named_scope :ordered, lambda {|*args| {:order => (args.first || 'created_at DESC')} } 

Then you can call:

@posts = Post.ordered.paginate :page => params[:page] 

The example above will use the default order from the named_scope (created_at DESC), but you can also provide a different one:

@posts = Post.ordered('title ASC').paginate :page => params[:page] 

You could use that with Romulo’s suggestion:

sort_params = { 'by_date' => 'created_at', 'by_name' => 'name' } @posts = Post.ordered(sort_params[params[:sort]]).paginate :page => params[:page] 

If params[:sort] isn’t found in sort_params and returns nil then named_scope will fall back to using the default order.

Railscasts has some great info on named_scopes.