Rails link_to parameters dictating flow of control in controller

Question

So I've been struggling a little in trying to understand exactly what I can do with a link_to in Rails. Some of what I've found is old, some is new, some is very different looking from what I've got. Specifically I'm trying to have two links in a view. One is "Add 1", one is "Minus 1". When I get to the controller I want to then add or subtract one from my model based on which link was used. Here are the links:

<%= link_to "Add 1", item, method: :put, title: item.name %>
<%= link_to "Minus 1", item, method: :put, title: item.name %>

My controller (item controller) method is:

def update
    @item = current_user.item.find(params[:id])
    @item.quantity += #+1 or -1 depending on what is passed
    if @item.save
        flash[:success] = "Item updated."
    end
    redirect_to current_user
end

Since I'm calling link_to with a :put I am not quite sure how to distinguish which :put is which, as both links are the same except for the name of the link. I think I'm identifying the specific item with the title: item.name parameter. Is it identified simply by item path? Should I change the ":title" to a "+1" or "-1"? I'd really appreciate clarification as this is confusing the hell out of me. I also noticed in the docs "html options" vs "url options" but I couldn't decipher the differences? Thanks!

Answer 1

You can pass additional parameters in the URL:

<%= link_to "Add 1", item_path(item, perform: 'add'), method: :put %>
<%= link_to "Sub 1", item_path(item, perform: 'sub'), method: :put %>

def update
    @item = current_user.item.find(params[:id])
    params[:perform] == 'sub' ? @item.quantity -= 1 : @item.quantity += 1 
    if @item.save
        flash[:success] = "Item updated."
    end
    redirect_to current_user
end

Or perhaps add member actions to your item resource:

resources :items do
  member do
    put 'sub'
    put 'add'
  end
end


link_to "Add 1", [:add, item], method: :put
link_to "Sub 1", [:sub, item], method: :put