Then maaaaaybe ...

```ruby
    @mappings = @site.mappings.order(:path).page(params[:page])
    @mappings = if params[:filter_field] == 'new_url'
       @mappings.redirects.filtered_by_new_url(params[:contains])
    else
       @mappings.filtered_by_path(params[:contains]) 
    end
```
(I mean, you know me, I'd prefer the ternary here, because :persevere:, but)