Ruby on Rails根据发布数据将记录保存在数据库中

Question

I've been playing around with this for the past 6 hours and I really can't solve it. I'm new to ruby on rails. I have a products and I have added a purchases model. now I want a 'buy' key next to each product to add it to my purchases database. This is my Purchases controller:

class PurchasesController < ApplicationController                                  
    def new
    end
    def update
    end
    def create
            @purchase = Purchase.new(purchase_params)
            if Purchase.save
                    redirect_to products_path notice: 'Product bough'
            else
                    redirect_to products_path notice: 'Error!!!'
            end

    end
    private
    def purchase_params
            params.require(:product).permit(:amount,:product_id)
    end

And the buy button:

<td><%= link_to 'Buy',purchases_path(product.attributes), method: :post %></td>

And that's within <% @products.each do |product %> . Now I really wanna know how to send product_id and then save it in my purchases database. I keep getting all sorts of errors! Like parameter not found: product to undefined method permit' for "8":String 8 is the product id and method save is undefined ...`. I think I really don't know what I'm doing here! A little help or tutorial on how to manually save data to database will be appreciated. (by manually I mean entering which posted field to saved for which col)

Answer 1

您应该执行@purchase.save ，而不是Purchase.save

Answer 2

Something like this should be your view.

<% @products.each do |product| %>
<td><%= product.amount %><td>
<td><%= form_for @product, url: {action: "create"}, html: {method: "post"} do |f| %>
  <%= f.hidden_field_tag :id,product.id%>
  <%= f.hidden_field_tag :amount,product.amount%>
  <%= f.submit "Create" %>
<% end %></td>
<% end %>

Your controller should look something like this:

def create
  @purchase = Purchase.new(purchase_params)
  if @purchase.save
    redirect_to products_path notice: 'Product bough'
  else
    redirect_to products_path notice: 'Error!!!'
  end
end

def purchase_params
  params.require(:product).permit(:amount,:id)
end

---

I am not sure why you want to not use the form. Why is that? Anyway here is a solution.

<td><%= link_to 'Buy',purchases_path(amount: product.amount,id: product.id), method: :post %></td>

This should work. Try this.