Rails中的form_for迭代在创建时添加了模型的所有实例

Question

I have an Order and Items , with join table OrderItems that act as line items in an order. In order#show , I want to display all instances of Items and be able to add this to the order through creating a new OrderItem . The issue is that when I post the form, order_item#create makes 40 new order_items for all Items , instead of just creating one instance of OrderItem for that one item I want to add.

Here is the OrderItems controller:

def create
    @order_item = @order.order_items.build(order_item_params)

    if @order_item.save
        flash[:notice] = "Your item was added"
        redirect_to [@user, @order]
    else
        flash[:error] = "Your item was not added. Please try again."
        redirect_to [@user, @order]
    end
end

Here is the form in order#show

<% @items.each do |item| %>
    <div>
        <%= form_for [@user, @order, @order.order_items.create(:item_id => item.id)] do |f| %>
            <div class="form-group">
                <%= f.label item.name %>
                <%= f.label "$#{item.price.to_s}" %>
            </div>
            <div class="form-group">
                <%= f.label 'quantity' %>
                <%= f.text_area :quantity %>
            </div>
            <div class="form-group">
                <%= f.label 'item id' %>
                <%= f.text_area :item_id %>
            </div>
            <div class="form-group">
                <%= f.submit 'Add Item', class: 'btn' %>
            </div>
        <% end %>
    </div>
<% end %>

Answer 1

Actually, the order_item#create action isn't creating the 40 order_items . It's your form:

<%= form_for [@user, @order, @order.order_items.create(:item_id => item.id)] do |f| %>

Change the create to build and that way it won't save the 40 instances. It will only save the one you hit submit for.