undefined method `capable_of_hosting_filter_related_icons?'

Question

I am continuing my foray into rails. I am implementing the wice_grid gem and following the instructions in the readme file. I converted the example erb file to haml. Below is my haml view:

 - grid(@vendors_grid) do |g|                  
  g.column do |vendor|                    
  vendor.                              
  end                                     
  g.column  do |vendor|                     
  vendor.                           
  end                                     
  g.column do |vendor|                      
  vendor.                     
  end                                     
  g.column do |vendor|                      
  vendor.
  end                                     
  g.column do |vendor|                      
  link_to('Edit', _path(vendor)) 
 end                                     
end                           

I cannot find a solution to the error I am receiving on - grid(@vendors_grid) do |g| this line. Need help. The error I am getting is 'undefined-method-capable-of-hosting-filter-related-icons'

Thank you.