Rails 3.1 :has_many, :through 复杂排序

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问题描述

我有一个包含 line_items 和供应商的订单模型.显示订单时，我想按供应商对 line_items 进行分组.

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

我想显示供应商和订单项的排序列表:

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

  ...

我现在的想法是

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

请帮忙.我想不通.也许这可以通过排序来完成?

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

如果订单只有一个供应商，那么我只想显示一个供应商.

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

[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}

然后在视图中:

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

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vendors