Question

I have an orders model with line_items and vendors. When displaying an order, I want to group line_items by vendors.

class LineItem < ActiveRecord::Base
  belongs_to :order
  belongs_to :vendor
end

class Order < ActiveRecord::Base
  has_many :line_items
  has_many :vendors, :through => :line_items
end

class Vendor < ActiveRecord::Base
  has_many :line_items
end

I want to display a sorted list of vendors and line items:

You have placed an order for the following items:

  Vendor 1
    Line item 1
    Line item 2
    Line item 3

  Vendor 2
    Line Item 4
    Line Item 5

  ...

My current thought is

order.vendors.each do |a_vendor|
  a_vendor.name
  !!?? AND THEN WHAT GOES HERE ??!!
end

please help. I can’t figure this out. maybe this could be done by sorting?

If the order only has one vendor, then I only want to show the one vendor.

Answer 1

How about this:

<% @order.line_items.all.group_by{|i| i.vendor}.each do |vendor, items| %>
  <%= content_tag :h2, vendor.id %>
  <ul>
  <% items.each do |i| %>
       <%= content_tag :li, i.id %>
  <% end %>
  </ul>
<% end %>

[edits]

sort_by(&:vendor) is the same as sort_by{|v| v.vendor}, but the block-style syntax gives you a little more flexibility. For example, you can sort by vendor name in the controller with:

@sorted = @order.line_items.all.group_by(&:vendor).sort_by{|vendor, items| vendor.name}

Then in the view:

<% @sorted.each do |vendor, items| %>
  <%= content_tag :h2, vendor.name %>
  <ul>
  <% items.each do |i| %>
       <%= content_tag :li, i.id %>
  <% end %>
  </ul>
<% end %>