Question

我有一个模型，我将一些相关数据存储在这样的哈希中：

line_items_attributes"=>[{"major"=>"8762", "minor"=>"322", "description"=>"Engineering", "amount"=>"200000", "active"=>"1"}, {"major"=>"8762", "minor"=>"445", "description"=>"Tanks", "amount"=>"2100000", "active"=>"1"}, {"major"=>"8762", "minor"=>"500", "description"=>"Pipe, Valves & Fittings", "amount"=>"150000", "active"=>"1"}]

我这样做是为了避免其他相关模型等。

我在这个网站上玩这个原型：

http://daniel.fone.net.nz/blog/2013/10/19/prototyping-web-applications-in-rails-4/?utm_source=rubyweekly&utm_medium=email

无论如何，我想要所有'数量'值。我用谷歌搜索了一些解决方案但我对哈希的了解还不够清楚。

我试过了：

2.0.0-p247 :053 > line_items_attributes.inject(0) {|sum, hash| sum + hash["amount"]}
TypeError: no implicit conversion of String into Integer
    from (irb):53:in `[]'
    from (irb):53:in `block in irb_binding'
    from (irb):53:in `each'
    from (irb):53:in `inject'
    from (irb):53
    from /Users/dan/.rvm/gems/ruby-2.0.0-p247@global/gems/railties-4.0.0/lib/rails/commands/console.rb:90:in `start'
    from /Users/dan/.rvm/gems/ruby-2.0.0-p247@global/gems/railties-4.0.0/lib/rails/commands/console.rb:9:in `start'
    from /Users/dan/.rvm/gems/ruby-2.0.0-p247@global/gems/railties-4.0.0/lib/rails/commands.rb:64:in `<top (required)>'
    from bin/rails:4:in `require'
    from bin/rails:4:in `<main>'

我甚至尝试添加hash [“amount”]。to_i但是没有用。我认为我很亲密，但我确信我错过了一些比较有经验的人。

在旁注中我看到其他哈希表示法显示如下：

line_items_attributes“=＆gt; [{major：”8762“，未成年人：”322“等对此有优势吗？

Answer 1

这对我有用：

2.0.0p247 :028 > line_items_attributes = [{"major"=>"8762", "minor"=>"322", "description"=>"Engineering", "amount"=>"200000", "active"=>"1"}, {"major"=>"8762", "minor"=>"445", "description"=>"Tanks", "amount"=>"2100000", "active"=>"1"}, {"major"=>"8762", "minor"=>"500", "description"=>"Pipe, Valves & Fittings", "amount"=>"150000", "active"=>"1"}]
 => [{"major"=>"8762", "minor"=>"322", "description"=>"Engineering", "amount"=>"200000", "active"=>"1"}, {"major"=>"8762", "minor"=>"445", "description"=>"Tanks", "amount"=>"2100000", "active"=>"1"}, {"major"=>"8762", "minor"=>"500", "description"=>"Pipe, Valves & Fittings", "amount"=>"150000", "active"=>"1"}] 

2.0.0p247 :036 > line_items_attributes.inject(0) {|sum, hash| sum += hash["amount"].to_i; sum}
 => 2450000

Answer 2

D'哦！再看一遍后，我错过了存储数据的实际情况：

{"line_items_attributes"=>[{"major"=>"8762", "minor"=>"322", "description"=>"Engineering", "amount"=>"200000", "active"=>"1"}, {"major"=>"8762", "minor"=>"445", "description"=>"Tanks", "amount"=>"2100000", "active"=>"1"}, {"major"=>"8762", "minor"=>"500", "description"=>"Pipe, Valves & Fittings", "amount"=>"150000", "active"=>"1"}]}

所以现在我跑了这个：

Model.find(1).data["line_items_attributes"].inject(0) {|sum, hash| sum + hash["amount"].to_i}

一切都很好。我可能不需要以那种方式存储它，但我只是以原型教程为例。

感谢那些花时间看这个的人。我已经把它想出来了......等等。

从散列中求和值

2 个答案: