ruby - Rails How to pass params in cross model system -

i unable figure out method pass params link tag. want when clicks on join group link, membership model shall have new row group_id current group id , user id current user id. membership model consists of 2 columns : user_id , group_id maps users groups. can me mistake making. here code groups : show.html.erb

    <p id="notice"><%= notice %></p>  <p>   <strong>title:</strong>   <%= @group.title %> </p>  <p>   <strong>desc:</strong>   <%= @group.desc %> </p>  <p>   <strong>creator:</strong>   <%= @creator.first_name %> </p> <%= link_to 'join group', memberships_path(:group_id => @group.id, :user_id => current_user.id ), method: :post %> <%= link_to 'edit', edit_group_path(@group) %> | <%= link_to 'back', groups_path %> 

and here memberships controller

class membershipscontroller < applicationcontroller   before_action :set_membership, only: [:show, :edit, :update, :destroy]    # /memberships   # /memberships.json   def index     @memberships = membership.all   end    # /memberships/1   # /memberships/1.json   def show     @membership = membership.find(params[:id])     @user = user.find(@membership.user_id)     @group = group.find(@membership.group_id)   end    # /memberships/new   def new     @membership = membership.new   end    # /memberships/1/edit   def edit   end    # post /memberships   # post /memberships.json   def create     @membership = membership.new(membership_params)      respond_to |format|       if @membership.save         format.html { redirect_to @membership, notice: 'membership created.' }         format.json { render :show, status: :created, location: @membership }       else         format.html { render :new }         format.json { render json: @membership.errors, status: :unprocessable_entity }       end     end   end    # patch/put /memberships/1   # patch/put /memberships/1.json   def update     respond_to |format|       if @membership.update(membership_params)         format.html { redirect_to @membership, notice: 'membership updated.' }         format.json { render :show, status: :ok, location: @membership }       else         format.html { render :edit }         format.json { render json: @membership.errors, status: :unprocessable_entity }       end     end   end    # delete /memberships/1   # delete /memberships/1.json   def destroy     @membership.destroy     respond_to |format|       format.html { redirect_to memberships_url, notice: 'membership destroyed.' }       format.json { head :no_content }     end   end    private     # use callbacks share common setup or constraints between actions.     def set_membership       @membership = membership.find(params[:id])     end      # never trust parameters scary internet, allow white list through.     def membership_params       params.require(:membership).permit(:user_id, :group_id)     end end 

you should have method in controller handles adding user group, like:

class membershipscontroller < applicationcontroller      ...      def join_group         @user = user.find(params[:user]         @user.group_id = params[:group_id].to_i     end      ...  end 

then routes.rb needs path controller method:

get 'memberships/join_group' => 'memberships#join_group' 

which result in path memberships_join_group_path use in link_to:

<%= link_to 'join group', memberships_join_group_path(:group_id => @group.id, :user_id => current_user.id ) %> 

the path you're using sending params index method.