部分章节还没有实做练习。
网上购买了安道的Rails指南中文版。联系了这个作者问了一个问题Rails5的翻译问题。
try(), 判断是否存在，不存在的话返回nil.例子：pasting
@person.try(:name) instead of: @person.name if @personatom订阅：
atom_feed()
atom_feed do |feed|
feed.title "Who bought #{@product.title}"
feed.updated(@latest_order.try(:updated_at))
@product.orders.each do |order|
feed.entry(order) do |entry|
entry.title "Order #{order.id}"
entry.summary type: 'xhtml' do |xhtml|
xhtml.p "shipped to #{order.address}"
xhtml.table do
xhtml.tr do
xhtml.th "Product"
xhtml.th "Quantity"
xhtml.th "Total Price"
end
order.line_items.each do |item|
xhtml.tr do
xhtml.td item.product.title
xhtml.td item.quantity
xhtml.td number_to_currency item.total_price
end
end
xhtml.tr do
xhtml.th 'total', colspan: 2
xhtml.th number_to_currency(order.line_items.map(&:total_price).sum)
end
end
entry.author do |author|
author.name order.name
author.email(order.email)
end
end
end
end
end
输出：curl --silent http://localhost:3000/products/1/who_bought.atom
得到xml格式的，可以在自己喜欢的阅读器上订阅这个Atom源。
<?xml version="1.0" encoding="UTF-8"?>
<feed xml:lang="en-US" xmlns="http://www.w3.org/2005/Atom">
<id>tag:localhost,2005:/products/1/who_bought</id>
<link rel="alternate" type="text/html" href="http://localhost:3000"/>
<link rel="self" type="application/atom+xml" href="http://localhost:3000/products/1/who_bought.atom"/>
<title>Who bought Rails, Angular, Postgres, and Bootstrap</title>
<updated>2018-04-02T13:19:44Z</updated>
<entry>
<id>tag:localhost,2005:Order/2</id>
<published>2018-04-02T13:19:44Z</published>
<updated>2018-04-02T13:19:44Z</updated>
<link rel="alternate" type="text/html" href="http://localhost:3000/orders/2"/>
<title>Order 2</title>
<summary type="xhtml">
<div xmlns="http://www.w3.org/1999/xhtml">
<p>shipped to beijing</p>
<table>
<tr>
<th>Product</th>
<th>Quantity</th>
<th>Total Price</th>
</tr>
<tr>
<td>Rails, Angular, Postgres, and Bootstrap</td>
<td>4</td>
<td>$440.00</td>
</tr>
<tr>
<th colspan="2">total</th>
<th>$440.00</th>
</tr>
</table>
<author>
<name>wangming</name>
<email>wangming@google.com</email>
</author>
</div>
</summary>
</entry>
</feed>