How to pass parameters between an index form and a new form in rails 4 -

i have form shows me list of 'challenges' each challenge can have many entries. user able create 'entry' entry has id of parent challenge.

i having difficulty passing id of parent challenge foreign key challenge_id of entry in new form

fields of challenge table are

id :integer rule :string 

fields of entry table are

id :integer challenge_id :integer title :string 

the views have are:

challenges/_index

<p id="notice"><%= notice %></p> <table>   <thead>     <tr>       <th>pointsspend</th>       <th>rules</th>       <th colspan="3"></th>     </tr>   </thead>   <tbody>     <% @challenges.each |challenge| %>       <tr>         <td><%= challenge.pointsspend %></td>         <td><%= challenge.rules %></td>         <td><%= challenge.id %></td>         <td><%= link_to image_tag("list.jpg"), entries_path, {:class => "allentrylink", :"data-challenge_id" => challenge.id}  %></td>       </tr>       <tr>     <td><div class="inline allentries" data-challenge_id="<%= challenge.id %>"></div></td>     </tr>     <% end %>   </tbody> </table> <br> 

entries/_index

<p id="notice"><%= notice %></p>  <table>   <thead>     <tr>       <th colspan="3"></th>     </tr>   </thead>   <tbody>         <td><%= link_to image_tag("add.jpg"), new_entry_path, id: "newentrylink" %>      <% @entries.each |entry| %>         <%= entry.blob %>         <%= image_tag entry.picture.url if entry.picture? %>     <% end %></td>   </tbody> </table> <br> <script> </script> 

the entries/new form

<%= form_for(@entry, html: { multipart: true })  |f| %>   <% if @entry.errors.any? %>     <div id="error_explanation">       <h2><%= pluralize(@entry.errors.count, "error") %> prohibited entry being saved:</h2>        <ul>       <% @entry.errors.full_messages.each |message| %>         <li><%= message %></li>       <% end %>       </ul>     </div>   <% end %>    <div class="field">     <%= f.label :blob %><br>     <%= f.text_field :blob %>     <%= f.file_field :picture %>    </div>   <div class="actions">     <%= f.submit %>   </div> <% end %> 

the controllers

class entriescontroller < applicationcontroller   before_action :set_entry, only: [:show, :edit, :update, :destroy]    def index     @challenge = challenge.find(params[:challenge_id])     @entries = entry.where(:challenge_id => @challenge.id)     render :layout => false   end     # /entries/new   def new     @challenge = challenge.find(params[:id])     @entry = entry.new     @entry.challenge_id = @challenge.id   end    def create   @challenge = challenge.find(params[:id])   @entry = entry.new(entry_params)   @entry.challenge_id = @challenge.id     respond_to |format|       if @entry.save         format.html { redirect_to @entry, notice: 'entry created.' }         format.json { render :show, status: :created, location: @entry }        else         format.html { render :new }         format.json { render json: @entry.errors, status: :unprocessable_entity }        end     end   end    def entry_params   params.require(:entry).permit(:id, :blob, :challenge_id, :picture)   end    private     # use callbacks share common setup or constraints between actions.     def set_entry       @entry = entry.find(params[:id])     end      # never trust parameters scary internet, allow white list through.     def entry_params       params.require(:entry).permit(:blob)     end end 

routes

get '/entries/new/:challenge_id', to: 'entries#new' resources :challenges, only: [:new, :create, :show, :index, :edit, :destroy]