Rails Unable to convert unpermitted parameters to hash

Question

I am trying to implement a simple search and sort for my webapp. I am following the railscast and this railscast.

My application helper for sortable function which I am using as link is:

def sortable(column, title = nil)
      title ||= column.titleize
      css_class = column == sort_column ? "current #{sort_direction}" : nil
      direction = column == sort_column && sort_direction == "asc" ? "desc" : "asc"
      link_to title, params.merge(:sort => column, :direction => direction, :page => nil), {:class => css_class}
    end

I am using these in the view. In the controller I am using white listing as:

 @listingssearch.where(:vehicletype => 'Car').order(sort_column + " " + sort_direction).paginate(:page => params[:page], :per_page => 30)

Private Methods for sanitization:

 private
     def sort_column
          Listing.column_names.include?(params) ? params[:sort] : "rateperhour"
        end

        def sort_direction
          %w[asc desc].include?(params[:direction]) ? params[:direction] : "asc"
        end

I tried using merge in the private method:

(Listing.column_names + params) but its not working 

For the helper methods I am getting an error when I am trying to provide search params to the sorting link: unable to convert unpermitted parameters to hash

It shows the error is for merge

link_to title, params.merge(:sort => column, :direction => direction, :page => nil), {:class => css_class}

The otherway around works fine:

<%= bootstrap_form_for listings_path, :method => 'get' do %>

        <%= hidden_field_tag :direction, :value => params[:direction] %>
        <%= hidden_field_tag :sort,:value => params[:sort] %>



        <div class= "col-sm-12 col-lg-12 col-md-12" style = "margin: auto;">
            <h6 style = "color:#7C064D;"><strong> PICK A DATE  <span class="glyphicon glyphicon-calendar"></span></strong>
            <%= date_field_tag :startdate, params[:startdate], placeholder: 'DATE' %>           
            </h6>
        </div>  

        <div class= "col-sm-12 col-lg-12 col-md-12" style = "margin: auto;">    
        <p>     
            <%= text_field_tag :near, params[:near], placeholder: ' Destination' %>
            <%= text_field_tag :radius, params[:radius], placeholder: ' Search Radius' %>
        </p>
        </div>      
        <div class= "col-sm-12 col-lg-12 col-md-12" style = "margin: auto;">    
        <p>     
            <%= text_field_tag :min, params[:min], placeholder: ' Minimum Rate Per Hour' %>
            <%= text_field_tag :max, params[:max], placeholder: ' Maximum Rate Per Hour' %>
        </p>
        </div>

        <div class= "col-sm-12 col-lg-12 col-md-12" style = "margin-top: 10px;">        
            <%= submit_tag "Search", class: "btn btn-info", style: "width: 40%; background-color: #E20049; border: #e20049;" %>
            <%= link_to 'View All', root_path, class: "btn btn-info", style: "width: 40%; background-color: #E20049; border: #e20049;" %>
        </div>

        <!-- <div class= "col-sm-6 col-lg-6 col-md-6" style = "margin-top: 10px;">      

        </div> -->


    <% end %>

My question is How to persist search params in sort helper methods in rails 5? What I am doing wrong?

Answer 1

In Rails 5, ActionController::Parameters no longer inherits from Hash, in an attempt to discourage people from using Hash-related methods on the request parameters without explicitly filtering them.

As part of this pull request, which was backported into Rails 5.1 and partially into Rails 5.0, an exception is raised if you try to call to_h on the parameters object without calling permit.

Calling merge on the original params object (params.merge(:sort => column, :direction => direction, :page => nil)) returns a new ActionController::Parameters object with the same permitted status (that is, permit has not been called on it). The link_to method then ends up calling to_h on that object, which raises the exception.

If you know which parameters should be allowed in the link, you can call permit with those listed.

params.permit(:param_1, :param_2).merge(:sort => column, :direction => direction, :page => nil)
# OR
params.merge(:sort => column, :direction => direction, :page => nil).permit(:param_1, :param_2, :sort, :direction, :page)

If you don't know which parameters could be included in the link, then it's possible to call request.parameters.merge(...) (as mentioned in this answer) or params.to_unsafe_h.merge(...). However, as pointed out in comments, this is a security risk when the result is passed to link_to, as a parameter like host would be interpreted as the actual host for the link instead of a query parameter. There are several other keys that also have special meaning in link_to (everything accepted by url_for, plus :method), so it's generally a risky approach.